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Fungi and Fungicides

A Practical Manual

CONCERNING THE

Fungous Diseases of Cultivated Plants

AND THE

Means of Preventing Their Ravages

BY

CLARENCE ISA. WKED, D. Sc,

ILL US TEA TED

LIBRARY
NEW Y#RK
BOTANICAL

N]
ORANGE JUDD COMPANY

1896

Sd735

By the Same Author

INSECTS ATnTD IKTSECTICIDKS

A Practical Manual Concerning Noxious Insects and the
Methods of Preventing their Injuries. Profusely Illus-
trated, 280 pages, handsomely hound in cloth with em-
bossed cover. Price, §1. 25.

SPRAYING CROPS

Why, "When and How. Illustrated. Second (Revised) Edi-
tion. Seventh Thousand. 130 pages. Price, 2.5 cents.

Copyright, 1894, by ORA^•GE JUDD COMPAKY

CONTENTS

Introduetion.

PART I. Fungi Affecting the Larger Fruits

Apple 27

Pear 41

Quince 47

Plum 53

Clierry 66

Peach 67

PART II. Fungi Affecting Small Fruits

Grape 79

Currant and Gooseberry . — 91

Raspberry and Blackberry .. 97
Strawberry 104

PART III. Fungi Affecting Shade Trees, Ornamental Plants
AND Flowers

Shade Trees Ill

Rose 114

Flowers 119

PART IV. FUNGI AFFECTING VEGETABLES

Bean 123

Beet 135

Cabbage 138

Celery 144

Onion 150

Cucumber and melon IGO

Potato 164

Sweet Potato 172

Spinach 176

Tomato 179

Seedlings 182

PART V. Fungi Affecting Cereal and Forage Crops

Oats 187

Wheat 194

Sorghum and Broom Corn . . . 214
Alfalfa 217

Indian Corn 202 Clover 219

m

Nothing illustrates so practically and satisfactorily the
importance and value of scientific investigation as the results
obtained by recent experiments in spraying with arsenites for
the destruction of insects, and with the copper solution or
Bordeaux mixture for the treatment of fungous diseases.
After long and patient study and experiment, scientijQc experts
have discovered several causes of the failure of the fruit crop,
and have recommended remedies which are i)roving effective
and reliable.

These discoveries are of inestimable value, since without
the remedies suggested the spread of diseases and the ravages
of injurious insects would soon have put an end to several
branches of the fruit industry. — W. C. Barry.

The day is not far distant when fungicides, and the means
of applying them, will be as much a part of the equipment of
a first-class farm — particularly one devoted to fruit or truck —
as is the cultivator or market wagon. — B. D. Halsted.

"We shall conquer when we know how. When we, with
open eyes and unstopped ears, as true students of nature, acquire
the knowledge within the possibilities of our reach, we shall
be able rightfully to assert our royal authority and effectually
to have dominion over every living thing that moveth upon the
earth. — T. J. Bur rill.

The time is rapidly approaching when a farmer or gardener
will as little dare to neglect the study of the physiology and
pathology of plants, as a surgeon dare practice without a knowl-
edge of anatomy, or a sailor hope to become a captain without
studying navigation. — H. Marshall Ward,

IT

PREFACE

The fungous diseases of cultivated plants inflict annually
upon American agriculture an enormous loss, a large propor-
tion of which might be saved by the application of the various
methods of prevention and remedy now known to be available.
The X)urpose of this book is to bring together in easily accessi-
ble form, the information concerning the injuries, life-histories,
characteristics and preventives of these diseases, now widely
scattered through scores of periodicals, bulletins, reports and
transactions. In preparing it, free use has been made of all
accessible writings upon the subject, a list of which would
include the contributions of nearly every American economic
mycologist, and of many in other lands. It pretends only to
the dignity of a compilation in which the compiler has utilized
both the facts and very often the language of others.

It would be difficult to find, in the annals of agriculture,
an instance in which knowledge of the highest practical value,
concerning a subject of first importance in the successful pro-
duction of the fruits of the earth, has been so rapidly evolved,
as has been the case during the last decade, in the investiga-
tion of plant diseases and their remedies. Scarcely ten years
have passed since there were barely half a dozen scientific men
in the United States working upon these problems, from an
economic standpoint. Of these, perhaps no one was doing so
much, both in original investigation, and in urging the neces-
sity that such studies be fostered by the State and general
government, as Professor T. J. Burrill, of the University of
Illinois. In 1886 Hon. Norman J. Colman, Commissioner of
Agriculture, recognized the importance of the subject, by estab-
lishing a mycological section of the botanical division of the
Department of Agriculture, and appointed Professor F. Lamson-
Scribner to take charge of the work. The wisdom of creating
the section was soon made manifest to the public at large, by
Professor Scribner's demonstration of the practicability of pre-
venting the ravages of the black rot of grapes, and other mala-

V

VI FUXGI AXD FUXGICIDES

dies of cultivated crops ; and the Department has been, ever
since, the chief center of interest in the development of knowl-
edge upon the subject. In 1888, Professor Scribner resigned,
for a ijrofessorship in the University of Tennessee, and was
succeeded bv Mr. B. T. Gallowav, under whose administration
the mycological section has been elevated to the Division of
Vegetable Pathology-, and has constantly increased in efficiency
and usefulness, now having a corps of trained experts who are
doing much to alleviate the ills of American agriculture.

Wlien, in 1888, the experiment stations were established in
the various States, the subject of plant diseases was at once
recognized as one of the important lines of work — it being, in
fact, specially mentioned in the organic law upon which they
were founded — and in many stations, investigators at once
began work upon the problems involved. Although scarcely
six years have since passed, results of immense practical
importance have already been obtained in these investigations
and experiments — such as the demonstration of the value of
the hot water treatment for grain smuts ; of tlie effects of the
Bordeaux mixture, and other fungicides, in preventing potato
blight and rot, as well as the plum leaf-spot, raspberry anthrac-
nose, apple scab, pear leaf-blight, and many other maladies ; of
the nature of various onion diseases, and methods of their pre-
vention ; and of the final discovery of the cause and cure of the
potato scab. It is safe to say that, had the experiment stations
done nothing more for agriculture than to obtain these and
other similar results concerning plant diseases, the money
spent upon them by the government would have been wisely
invested.

The authors, in connection with whose publications the
illustrations on the following pages originally appeared, are
indicated in the following list : After Arthur, figures 78, 79 :
Atkinson, figure 53 ; Bailev, plates II, XI, figures 10, 11, 21, 32,
33, 36, 37, 39: Beach, plates Yl. XIV, XV; Burrill. figure 87;
Chester, plate IX, figures 9. 88 ; Clinton, fi.gures 47, 48 ; Dudley,
plate XIII, figures 22, 23. 65, 66 ; Miss Detmers, plates I, XII ;
Fairchild. figures 34, 54 ; Farlow. plate IH, figure 7 ; Galloway,
plates IV. Yll, figures 8, 31 ; Carman, figures, 16, 18, 19, 49 ;
Halsted, 17, 20, 24, 46, 57-60, 64, 70-72, 75, 76; Miss Howell,
figures 89, 90 (in part) : Jones, figure 73 : Kinney, plate XVI ;
Kellerman and Swingle, figures 77, 80, 81 ; Lamson, plate V ;
Lugger, figure 2; Maynard, plate X; Pammel, figure 90 (in

PEEFACE Vll

part) ; Scribner, figures 38, 42-44, 50-52, 61-63 ; Seymour, 45,
86 ; E. F. Smith, plate VIII ; W. G. Smith, plate XVII ; Sorauer^
figures 13, 14 ; Thaxter, figures 56, 67-69 ; Tulasne, figure 84 ;
Waite, figure 15 ; Ward, figure 6.

I have aimed to treat of only the more destructive and
wide-spread fungous diseases, especially those for which prac-
tical remedies are known ; and have endeavored to give such a
concise account of the more important facts concerning these
as will enable the cultivator to combat them intelligently. A
few of the paragraphs in the following pages have already been
printed in my series of articles on Plant Diseases in the National
Stockman and the American Agriculturist; and in a few other
instances I have drawn upon my previous writings. I desire
also to express my obligations to the directors and other offi-
cers of a number of experiment stations — notably those of
Connecticut, Cornell University, Delaware, Kentucky, Massa-
chusetts, New York, New Jersey, New Hampshire, Ohio,
Rhode Island, and Vermont — for the use of plates of illustrations.

C. M. W.
New Hampshire College of Agriculture and Mechanic Arts.

Durham, January, 1894.

ilBRART
NEW Y#RK
BOTANICAti

GARDEN

FUNGI AND FUNGICIDES

INTRODUCTTION

Cultivated j^lants are beset by many enemies. Some
of these belong to the animal, and others to the vegeta-
ble kingdom. Of the former the insects, and of the lat-
ter the i^arasitic fungi are by far the most important.
By the development of these parasitic fungi upon grow-
ing crops the peculiar maladies known as fungous dis-
eases are produced ; and to these diseases American
agriculture annually sacrifices a large percentage of her
products. The money value of the loss thus sustained
is believed, by those who have studied the subject, to
amount to hundreds of milHons of dollars yearly.

It is difficult to determine definitely the amount of
damage inflicted over a wide area upon a given crop by
its fungus enemies, but it is safe to say that in most
cases it is much greater than is ordinarily supposed.
The following examples will serve to illustrate the mag-
nitude of the loss in the case of certain crops.

In 1886 Commissioner IST. J. Colman, of the United
States Department of Agriculture, after careful esti-
mates, stated : '^ We may safely assume that the yalue of
the corn and wheat annually destroyed in this country by
diseases induced by fungi is not less than 1200,000,000."
The average annual loss due to the rust of wheat in Illi-
nois alone has been estimated, by Professor T. J. Burrill,

1

2 FUifGI AND FUNGICIDES

at nearly half a million dollars ; and careful estimates
made by authoritatiye observers in widely separated
States indicate that the average yearly loss of oats in the
United States due to smut equals, or exceeds, one-tenth
the entire crop. Professor Kellerman estimated the loss
in Kansas, in 1888, at $1,382,328.31; and in 1889, at
8850,534.76. The loss in Indiana from the same cause,
in 1889, was estimated by Professor Arthur at $797,526 ;
and in 1890, at $605,352.

It is probable that fruits suffer an even greater pro-
portionate injury than do the grains. *'The blights
and rots of the fruit plantations," said Professor Burrill,
several years ago, ^^ would, if exactly and certainly ex-
pressed in dollars and cents, frighten cultivators from
their business." The loss from apple scab, throughout
most of the apple-growing regions of the country, ranges
from one-sixth to one-half of the entire product. The
strawberry blight, in many localities, often ruins crops
of this luscious fruit. The rots and mildews affecting
grapes have led to the extermination of hundreds of
vineyards. The loss of peaches from the brown rot on
the Chesaj)eake and Delaware peninsulas, in 1888, was
estimated by competent observers at from $400,000 to
$600,000. Similar statements could be made concern-
ing nearly all our fruits.

The vegetable and field crops, the flowers and orna-
mental plants, and even the shade trees, do not fare
much better. Xearly all have enemies that cause serious
damage. Over a large section of country the usual loss
of potatoes from fungus enemies varies from ten to
forty per cent, of the crop.

THE DEVELOPMENT OF PARASITIC FUNGI

To illustrate the life- history of the fungi causing
the fungous diseases of growing 2:)lants, we will begin
with a familiar example of vegetable life— the Indian

PARASITIC FUKGI '3

corn plant. When a kernel of corn is placed in a
warm, moist soil, it germinates by sending out a pointed
tube, called the radicle, or first root. This pushes into
the soil and, after a time, produces other roots, which
branch off in various directions. Soon after the radicle
starts, the little plant also sends upward to the air its
minute coiled leaves. While germinating, the young
plant is nourished by the food stored up in the starchy
portion of the corn kernel, but soon after the leaves
expand in the sunlight this source of food is exhausted,
and thereafter the plant relies upon its own resources
for the materials of growth. By means of the contin-
ually developing rootlets, it is able to draw from the
soil certain chemical compounds, such as water, potash,
phosphoric acid, etc., which are taken up through the
stem and distributed to the leaves, where, by the action
of the sunlight upon the chlorophyll — or the green por-
tion of the leaf — they are combined with the carbonic
acid of the air, and these simple chemical substances are
changed from inorganic to organic compounds, forming
starch, sugar, and various otiier products. The plant
continues growing, storing up in its leaves and stem
more and more of these highly organized materials which
it produces as it develops. It finally reaches a. point
where it begins j^i'eparing for reproduction ; on the mid-
dle or lower j^ortions of the stem it sends out its pistil-
late, or silky blossoms, and on the upper it produces the
staminate, or tassel flowers. The pollen from the latter
falls upon the former, and fertilizes the ovaries of the
embryo kernels. These then begin to develop, and
much of the starchy and other organic matter stored in
the stem and leaves is transferred to the cob and kernels.
The latter finally mature, and the cycle of vegetable life
is complete.

This is a fair illustration of the life-history of the
higher plants. Such plants are especially distinguished

FUXGI AXD FUNGICIDES

by the presence of chlorophyll, and the ability to con-
vert the inorganic elements of the soil and air into
highly organized compounds. But such ^ilants form
only a part of the yegetable life of the globe. There are
vast numbers of the so-called lower j^lants, like the toad-
stools, mushrooms, molds, mildews, rusts, smuts, blights,
and similar organisms, which are classed together under
the common name of fungus. The plural of fungus is
fungi — pronounced funji — or funguses. These fungi
differ greatly from each other; some rank comparatively
high in the scale of existence, and others rank low.

As an illustration of the higher fungi, we may take
one of the mushrooms so common in our fields and

woods. This plant repro-
duces by means of spores
— minute bodies, corres-
ponding in function to the
seeds of higher plants.
AVhen one of these spores
falls npon a moist soil,
rich in decaj^ing organic
matter, it germinates by
sending out a little tube
— much as the kernel of
corn sends out its germi-
nating radicle — and this
tube, after penetrating the
soil a short distance, sends
out side branches, which push about between the decay-
ing organic particles, absorbing nourishment from them.
These branches, in turn, send out other l)ranches, and
these form what is called the mycelium, or vegetative
portion of the fungus ; this continues developing be-
neath the surface for some time. Finally an unusual
development of mycelium takes place at one or a few
points, and from these there are rapidly produced a few

FIG. 1. MUSHROOM.

PARASITIC rUKGI

O

miislirooms, which may be sent up into the air above the
soil surface in a single night. Each mushroom (Fig. 1)
consists of a stem commonly surmounted by an umbrella-
like cap, on the under side of wliich are many thin ver-
tical jilates. Between thece plates vast numbers of
spores are soon produced, to fall to the ground, or to be
wafted hither and thither by the winds. As soon as the
spores are ripe the fungus dies. It will be noted that
this plant has no chlorophyll,
and is simply nourished by
dead and decaying organic
matter. Fungi like this are
said to be sapropliytes, or
saiJropliytic, a w^ord meaning
living on decaying materials.
Such plants, as a rule, do no
direct injury to other kinds
of vegetable life.

There are many kind;^ of
fungi which, instead of living
upon dead or decaying organic
matter, develop at the expense
of other living organisms.
Consequently these are said
to be parasitic in their nature.
Some of these live within the
bodies of animals, often kill- fig. 2. chinch bugs affected
ing their hosts, and others ^'^ fungus.

live within the tissues of the higher plants. A good
example of the former is seen in the fungus which de-
stroys chinch bugs, represented in Fig. 2. A number
of dead bugs are shown on a wheat stalk on the left,
while a single bug, much magnified, covered with the
fungus, is represented at the right. This fungus belongs
to a genus of plants called by botanists Entomophthora.

To illustrate the manner of development of the par-
asitic fungi affecting higher plants, we may take the

6 PUXGI AND FUXGICIDES

downy mildew wnlcli causes the well-known rot of the
Irish potato. It is now believed that this disease does
much less damage in America than has been commonly
supposed, the injury attributed to it being often due to
other fungi, but it is sometimes destructive, and its life-
history has been carefully studied.

The first indication of the presence of the downy
mildew in the potato field usually is the appearance of

FIG. 3. DISEASED POTATO LEAF.

brownish spots upon the leaves. As the disease pro-
gresses these spots gradually enlarge, finally involving
the whole leaf, w^hich turns dark brown or blackish.
Then neighboring leaves become affected, and the whole
plant eventually wilts and dies.

PARASITIC FUNGI 7

If one looks closely at the under surface of the leaf
beneath the brown spots, he will see, in case this fungus
is present, a w^hitish velvety mold. By making a thin
cross-section of the leaf at this point, and putting it
under the microscope, an appearance similar to Fig. 4
will be seen. At -the right is one of the long pointed
hairs which grow naturally upon the under surface of
the healthy leaf ; next to this toward the left is another
peculiar leaf-hair v/ith a club-like tip ; and beyond this

FIG. 4. SECTION" OF POTATO LEAF SHOWING DEVELOPMENT OP

MILDEW.

project the hyph^e, or fruiting threads of the fungus,
which give off branches on which are borne small oval
bodies. The latter are the spores, or conidia, of the
fungus. They are the bodies by means of which the
fungus reproduces itself, and are developed on the
infested leaves in enormous numbers.

These conidia are easily dispersed by slight air cur-
rents, and are carried far and wide en the wings of the

8

PL'XGI AND PL'XGICIDES

FIG. 5. POTATO 3IILDEW

wind. When one of tliem falls upon a moist potato
leaf it germinates by a very peculiar method : The
inside of the spore is composed of a granular substance
which at this time divides into several individual parti-
cles, that escape through an opening in the smaller end
of the spore wall, as seen in h. Fig. a. Each of these
particles now develops two minute hair-like projections,
called cilia, as seen at c, by means of which it swims
around in the drop of water ; these are called swarm-
spores, or zoospores.
After a short time these
swarm-spores come to
a rest, absorb the cilia,
and change from the
oval shape to one more
spherical (d) \ each
then germinates by
sending out a little

a, conidinni; b, same, with contents escaping: rrprminnfino' fnhp
c, swann spores; d, same, come to rest and ociuiiuu-uiiii^ i>u uc,

germinating. Something as a kernel

of corn sends out its germinating radicle, as shown in
the two fiofures beside d.

In case these swarm-spores germinate on the surface
of a potato leaf on or near to one of the breathing pores,
or stomata — the peculiar openings with which both sur-
faces of most leaves are provided — the germ tube passes
to the interior of the leaf through it, as shown at a,
Fig, 6. If no breathing pore is in the immediate vicin-
ity, the germinating spore bores through the cell wall,
as shown at c.

After the jiarasitic fungus has thus entered the
inside of the leaf it develojos rapidly at the expense of
the tissues of the latter. It j)ushes its threads, or
JiypJice, about between the cells, choking up the cavities
which occur in the healthy leaf, and absorbins^ the con-
tents of the cells. In many species of Peronospora the

PARASITIC FUXGI

9

threads that run between the cells send into the cells
themselves little processes called "suckers," or haustoria,
which assist in absorbing the cell contents. Thus, in
the downy mildew of the grape this occurs in a way
illustrated at Fig. 7. Tliese threads running through
the leaf lead to the disorganization of its tissues, causing
the cells to collapse and turn brown. When they have

FIG, 6. SURFACE OF POTATO LEAF GREATLY MAGNIFIED, SHOWING
GERMINATING SPORE ENTERING BREATHING PORE AT a,
AND GOING THROUGH EPIDERMIS AT C.

developed to a considerable extent they collectively form
the mycelinm of the fungus.

After the Peronospora plant has reached this stage
in its existence it is ready to prepare for reproduction.
It sends out through the breathing pores of the leaf
branching threads, and on these develops the conidia, as
already described.

By means of these conidia, which are produced in
great abundance, and the swarm-spores originating from

10 rUXGI AND FUXGICIDES

them, the fungus is able to multiply with marvelous
rapidity during the warm, damp weather most favor-
able to its growth. "In an ordinary potato field the
abundant foliage, wet with rain and full of juices
such as would favor the growth of the mycelium, is
swayed by the wind, and leaf flaps upon leaf over the
whole area ; quite apart from the wind-blown conidia,

the active zoospores can
soon spread from any one
center, and at once infect
new leaves. In a few
hours fi'esh disease-spots
are developed, each put-
ting forth new crops of
FIG. 7. sECTTox OF TLEAF sHowryG couldla, whlch again ger-
MYCELiuM OF FUNGUS, ^lAGxiFiED. niinatc aud send out zoo-
spores, and so on." Under these conditions it is easy
to see that the attack may be sudden and destructive.

Besides these conidia, or summer spores, many par-
asitic fungi develop in autumn certain spores, by means
of which the fungus passes through the winter. The
latter are usually better protected than the conidia.
They are sometimes called winter-spores.

Besides the saprophytic and parasitic fungi discussed
above, there are some which partake of the nature of
both, belonging to one class during a portion of their
development, and to the other during the rest. For
example, the black rot of grapes is at first a true parasite
attacking the healthy parts of the vine, but it completes
its growth as a saprophyte, living upon the decaying
berries.

EELATIO:S' OF THE WEATHER TO FUXGOUS DISEASES

There is a common idea that the weather is respon-
sible for a large proportion of plant maladies. In an
indirect wav this is often true, but the condition of the

METHODS OF STUDTIXG FUNGI 11

atmosphere never directly causes a fuiigons disease.
Such diseases, as ah-eady indicated, are produced by
minute plants, which never arise spontaneously, but
always from some spore, or other reproductive form of a
previously existing plant of the same species. But
weather conditions may be favorable to the rapid devel-
opment of these fungi, and so indirectly cause the
diseases.

METHODS OF STUDTIXG FUN^GI

The successful studv of the minute characteristics
of most fungous diseases requires the use of a compound
microscope. These, however, can be obtained for a
comparatively small amount, and will well repay the
investment in the wondei's revealed. Bv the aid of some
such little book as Phin's ^'How to Use the Microscope,''
or Bausch's ^^Manipulation of the Microscoj^e," almost
anyone can learn how to manipulate a microscope, and
can examine the microscopic characters of the various
fungi affecting crops. One desiring to undertake such
study would find the following books helpful :

Bennett & Murray : Cryptogamic Botany.

Burrill : Parasitic Fungi of Illinois.

Plowrio-ht : British Uredinite and Ustilao-inife.

Scribner : Fungous Diseases of the Grape and Other
Plants.

Smith : Diseases of Field and Garden Crops.

Ward : Diseases of Plants.

The bulletins of the United States Department of
Agriculture, especially the Journal of Mycology, and of
the various experiment stations, will also prove very
useful.

METHODS OF DISTRIBUTIOis"

There are many ways in which fungous diseases are
distributed, although the commonest one is by means of

12 fu:n'gi and fungicides

the various kinds of summer sj^ores. With the great
majority of diseases these are i^roduced in countless
numbers, and as they are wafted hither and thither by
every breath of wind, are washed from leaf to leaf and
from leaf to root by rains, and germinate quickly in
their new situations, they are able to spread infection
with marvelous rapidity. They are also, no doubt, often
carried from place to place by insects and birds, adher-
ing to some part of their bodies, especially the feet.

The various other kinds of sj)ores produced by the
fungi discussed in the following pages are also distrib-
uted by similar agencies. Some of the smuts, as well,
no doubt, as many other diseases, are often spread
through the field in barnyard manure ; and in cases like
the onion smut, the spores may be washed, with loose
soil, from higher to lower levels. The spores of certain
grain smuts appear to be able to joass from diseased to
healthy kernels during the process of threshing, and,
in some cases, the disease may be spread by means of
hoes and other implements used in cultivation.

In diseases like the scab and blight, or rot of pota-
toes, the mycelium of the fungus is often distributed in
the tubers used for seed, thus being ready to infect the
new crop as soon as it gets well started.

METHODS OF PREYEXTIOi^

There are man}' ways in which the injuries of fun-
gous diseases may be prevented. Among the more im-
portant of these are the following :

Fertilization and Cultivation. — As a general
rule, — not, however, without important exceptions, —
plants weakened in vitality are more subject to the
attacks of parasitic fungi than those in vigorous growth.
Consequently metliods of cultivation and fertilization
which tend to produce rapid development and early ma-
turity, are to be adopted as far as practicable.

METHODS OF PKEVENTIOK 13

Selection of Resistant Varieties. — It has long
been observed that with many crops certain varieties are
more liable to fungous diseases than others. The reason
of this, in many cases, is not well understood, but the
fact will lead the careful cultivator to select such varie-
ties as prove most resistant, other things being equal, in
his locality. Dr. B. D. Halstead has recently shown
that plants with variegated foliage are much more sub-
ject to fungns attack than those with green leaves.

Rotation of Crops. — The spores of the great ma-
jority of j^arasitic fungi pass the winter on or in the soil
where the crop attacked was grown, and if a cro23 of the
same kind is planted there the next season it is almost
certain to be infested. The onion smut is a striking
example of this. In consequence, the proper rotation
of crojjs is not only desirable, but often imperatively
necessary. The rotation should be so arranged that
each crop will not be liable to attack from the diseases
of the preceding crop.

Clean Culture. — Injurious fungi may be largely
destroyed by keeping the farm premises clean and free
from weeds and rubbish. Burning potato tops, old
tomato vines, and similar refuse, will destroy millions of
spores. Some fungi which infest cultivated crops also
grow upon weeds, and, hence, keeping the ground free
from the latter may prove of great benefit to the former.
Care should also be taken not to distribute the spores by
means of stable manure.

Mechanical Exclusion. — It is often practicable
to prevent the spores from reaching the crop by methods
of mechanical exclusion. The most familiar example of
this is to be found in the practice of bagging grapes to
prevent their rotting. Small paper sacks are tied over
the bunches as soon as the fruit is well formed, and
allowed to remain until it ripens. The sacks exclude
the rot spores, and also prevent insect attack.

14 FUXGI AXD FUXGICIDES

Hand Picking. — With diseases like the brown rot
of peaches and j^hims, plum pockets, etc., mnch may be
done in reducing injury by persistent hand-picking of
the affected parts, which, of course, should be burned
or buried deeply in the soil.

Use of Non-infected Seed. — Xumerons fungous
diseases start from the seed. For instance, the potato
rot exists in seed potatoes, and so infects the new crop.
In such cases care should be taken to obtain seed not so
infected, or, when j^ossible, so to treat the seed that the
sj)ores are destroyed.

Destruction of Alternating Forms. — As shown
on other pages, some of the rusts exist in two or more
forms on different host-j^lants. For instance, the apple
rust has one form that produces '^ cedar balls" on cedar
trees. The destruction of the latter will prevent the
development of the former.

Use of Fungicides. — The most practicable way of
preventing the great majority of the fungous diseases of
cultivated crops is by the use of fungicides (a word
meaning, literally, killers of fungi). These are discussed
more fully under the following heading. The majority
of them are ai)2olied externally to plants by spraying or
dusting. In such cases they may act in either or both
of two ways : (1) By directly destroying any fungus
spores present at the time of application ; and (2) by
remainino- on the surface in a condition to destrov, either
before germination or during that process, any sjiores
that may light upon the j^lant thereafter.

THE IMPORT AXT FUisGICTDES

The followino- list includes the fun2:icides that have
proved of practical value up to the present time. It is a
list, however, that will probably be extended during the
next decade, as experiments are constantly progressing
to learn the fungicidal value of many other substances.

THE IMPOETAKT f UXGICIDES 15

Water. — The use of water heated to 132|-° F. has
recently come into practice to destroy the spores of grain
smuts in or on the seed. The water should not get
above 135°, nor below 130°, while the seed is immersed.
Full directions for this treatment will be found in the
discussion of wheat and oats smuts.

Bordeaux Mixture. — This fungicide originated
in France, and has become one of the leading combina-
tions of copper salts. Since its introduction into Amer-
ica there has been a constant tendency to dilute the mix-
ture more and more. The results from the diluted
mixtures have been apparently as good as from those of
full strength, and, of course, the cost has been propor-
tionately lessened. The different formulas are indicated
below :

Original Formula. — Dissolve six pounds of copper
sulphate in one gallon of hot water in an earthen or
wooden Yessel. In another vessel slake three pounds of
fresh lime in one gallon of water. Strain the latter and
add to twenty gallons of water. Now pour in the dis-
solved copper sulphate and mix thoroughly. Keep the
mixture stirred while using.

Half- strength Formula. — In 1889, while at the
Ohio Experiment Station, I experimented with potato
blight by diluting this mixture a little more than half,
using six pounds of copper sulphate and four pounds of
lime to a barrel (fifty gallons) of water, instead of
twenty-two gallons. This was applied to a number of
plants besides potatoes, and, apparently gave as good
results as undiluted mixtures. The same formula was
also successfully used in 1890, and has since been quite
generally adopted, being now recommended by the
United States Department of Agriculture. Mr. Gallo-
way suggests the following method of procedure :

'*In a barrel that will hold forty-five gallons dissolve
six pounds of copper sulphate, using eight or ten gallons

16 FUXGI AXD rUXGICIDES

of water, or as muctu as may be necessary for the pur-
pose. In a tub or half barrel slake four pounds of fresh
lime. When completely slaked add enough water to
make a creamy whitewash. Pour this slowly into the
barrel containing the copper sulphate solution, using a
coarse gunny sack stretched over the head of the barrel
for a strainer. Finally fill the barrel with water, stir
thoroughly, and the mixture is ready for use. Prepared
in this way the cost of one gallon of the mixture will
not exceed one cent, the price of copper sulphate being
seven cents per j^ound, and lime thirty cents per bushel.
In all cases it is desirable to use ^^owdered copj^er sul-
phate, as it costs but little more and dissolves much
more readily. It is highly important also that fresh
lime be used."

TMrd-strengtli Formula. — In 1S91 Mr. AV. J.
Green, of the Ohio Exj^eriment Station, used on a2:>ples,
plums, pears, cherries, raspberries, etc., a still more
dilute mixture, yiz., four pounds of copper sulphate and
four pounds of lime to fifty gallons of water, and ob-
tained very good results. The cost of the copper sul-
phate in a barrel of this mixture is less than one-third
the cost of that in a barrel j^repared according to the
original formula.

A still more dilute mixture is recommended by the
Rural New Yorker, and jDrobably, in some cases, is as
effective as any of the above, while also cheaper. It is
''one ounce of copper sulphate and three-fourths of an
ounce of lime to each gallon of water ; that is to say,
two pounds of copper sulphate and one and one-half
jDOunds of lime to thirty-two gallons of water." A
special advantage of the Bordeaux mixture is, that Lon-
don purple or Paris green can be added to it, making a
combined insecticide and fungicide.

Care should be taken not to use the Bordeaux mix-
ture on fruit crops too late in the season. Traces of it

THE IMPOKTA.NT FU:N'GICIDES 17

remain for some time, notwithstanding numerous rains,
and are liable to cause unnecessary suspicions wlien on
marketed fruit. When a fruit crop requires treatment
within a month of the time of jDicking, it is better to
substitute some fungicide like eau celeste or carbonate
of copper, but it is doubtful if even these combinations
should be applied so near the time of the fruit harvest.
With nearly, if not quite, all of our fruit diseases, the
treatment should begin early and not continue too late.

It sometimes happens that traces of Bordeaux mix-
ture remain upon the fruit, even when a considerable
interval elapses between the last application and the
ripening of the fruit. Such traces may be easily re-
moved by dipping in a solution made by adding two gal-
lons of cider vinegar to ten gallons of water. A good
way is to have three tubs, one holding the vinegar mix-
ture, and the other two pure water. Then j^lace the
grapes or other fruit in wire baskets holding fifteen to
twenty 230unds, dip them in the vinegar tub for five
minutes, and then rinse in the two tubs of clear water,
afterwards spreading the fruit on frames or shelves,
something like those used in fruit evaporators. Grapes
can be treated in this way on a large scale for six cents a
hundred pounds, and their appearance for market is not
injured to any appreciable extent.

The Bordeaux mixture must be kept well stirred in
the reservoir during application. A paddle in the bar-
rel, something like that of an old-fashioned churn, is
one of the most efficient agitators. The addition of
enough soap to make a slight suds has been recom-
mended, as causing the mixture to spread more evenly
over the plants.

Eau Celeste. — This is made by dissolving two

pounds of copper sulphate in six or eight gallons of

water in an earthen or wooden vessel (such as the large

crocks used for butter, or wooden pails or tubs), then

2

18 rUXGI AXD PUXGICIDES

adding one quart of ammonia and mixing with fifty or
sixty gallons of water.

Modified Eau Celeste. — Dissolve four pounds of
sulpliate of copper in ten or twelve gallons of water,
and stir in five pounds of washing or sal soda ; dissolve
one and one-fourth pounds of sal soda in hot water,
then add three pints of ammonia and dilute to fifty gal-
lons of water.

Carbonate of Copper. — This is commonly used
in the form of an ammoniacal solution, made by dissoly-
iug four ounces of carbonate of copper in two quarts of
ammonia, and then adding to a barrel of water. The
carbonate will dissolve more readily if mixed with water
enough to form a paste before it is added to the ammo-
nia. It is a simple fungicide, easy to make and apply,
and as it is a clear solution there is no trouble with its
clogging nozzles. It has been successfully used to' pre-
vent apple scab, yarious mildews, etc.

Inasmuch as commercial copper carbonate is rather
expensive, costing thirty-five to forty cents per pound
at wholesale. Professor F. D. Chester advises that it
be prepared at home according to the following method,
in which case it costs, for materials, but fourteen cents
per pound :

^'^ Dissolve in a barrel twenty-five pounds of copper
suljDhate in hot water. In another barrel dissolve thirty
pounds of sal soda in hot water. Allow both solutions
to cool, then slowly pour the solution of sal soda into
the copi:)er sulphate solution, stirring the same. Fill
the barrel with water and allow the precipitate of copper
carbonate to settle. Upon the following day siphon off
the clear supernatant liquid, which contains most of the
injurious sodium sulphate in solution. Fill the barrel
again with water, and stir the precipitate vigorously
into suspension ; again allow the precipitate to settle,
and again on the following day siphon off the clear

THU IMPORTAKl^ FUNGICIDES ID

liquid. This operation washes the carbonate free of
most of the sodium sulphate which contaminates it.
Make a filter of stout muslin, by tacking the same to a
square wooden frame which will just fit over the open
top of the second barrel, letting the muslin liang down
loosely so as to form a sack; through this filter the pre-
cipitate, so as to drain off the excess of water, and as the
filter fills remove the precipitate, and allow it to dry .in
the air, when it is ready for use. The operation is not
troublesome, and can be carried on in connection with
other work."

Potassium Sulphide. — Dissolve one-half ounce
of potassium sulphide (liver of sulphur) in one gallon of
hot water. When cold apply in a spray. Used to pre-
vent gooseberry mildew and similar diseases. Commer-
cial liver of sulpliur costs fifteen to twenty cents per
pound.

Soda Hyposulphite. — Dissolve one-half ounce, or
one ounce of soda hyposulphite in ten gallons of water.
This is recommended by some for gooseberry mildew
and apple scab, but it is not in general use.

Sulphate of Copper. — Besides its use in combi-
nation with other substance, copper sulphate is often
ajoplied to vines and trees early in spring to destroy the
winter spores of fungi. For this purpose it is used in a
simple solution made by dissolving tw^o pounds of the
coj)per sulphate in fifty gallons of water.

Copper Chloride. — This is a greenish crystalline
salt of copper, readily soluble in water, which has been
recently tested as a fungicide at the Cornell University
Experiment Station, with encouraging results. It is
said to cost, at retail, about ten cents an ounce, or fifty
cents a pound. Used at the rate of one and one-half
ounces to twenty-two gallons of water it injured peach
and apple foliage. So little is now known of it that no
practical recommendations can here be made, other than
that it i^ worth exporimentiii^r with.

20 FUXGI AND FUXGICIDES

Sulphur. — Flowers of sulphur form a valuable
fungicide to use against various mildews and other dis-
eases. The powder may be applied directly to the sur-
face of the plants to be protected, or used as a wash, or
in fumes.

COMBIXIXG FUJ^GICIDES WITH IXSECTICIDES

It is often desirable, in applying the fungicides
used in spraying, to combine with them certain insecti-
cides, to destroy insects attacking the crop at the same
time. The advantasres of this, in savinof time and ex-
pense, are obvious. The following two combinations
have been found practicable :

Bordeaux Mixture and Arsenites. — Add four
ounces of London purple or Paris green to fifty gallons
of Bordeaux mixture. This is one of the very best
combined insecticides and fungicides. It can be used
safely and effectively upon a great variety of crops —
such as potatoes, for Colorado beetles and blight ; apples
and pears, for insects and scab ; and plums and peaches,
for curculio and leaf or fruit diseases. To use upon
fruits the Green formula is probably the best, as too
large an amount of copper sulphate occasionally prevents
the perfect development of apples and pears. The
remarks on page 16, concerning late applications of
the Bordeaux mixture, are equally applicable to this
combination.

Copper Arsenic Solution. — The Ohio Experi-
ment Station recommends the following combination :
Copper carbonate, six ounces ; Paris green, four ounces ;
ammonia, two quarts; lime water, fifty gallons. "The
cop23er carbonate and Paris green may be mixed and dis-
solved in the ammonia (more or less ammonia wall be
required, according to the strength), after which add
the lime water. By lime w^ater is here meant clear lime
water made by dissolving as much lime in water as it

COST OF rUKGICIDE MATERIALS 21

will take up. One- fourth of a pound of lime to a barrel
of water is as much as is required for the purpose of pre-
venting the injury to the foliage Avhicli the Paris green
might cause. A convenient method is to put several
pounds of lime in a barrel, and then fill with water;
after stirring vigorously allow to settle, when the clear
water may be used. The barrel may be filled with water
each time before going to the orchard, and allowed to
stand while gone." Only sufficient ammonia to dissolve
the copper carbonate and Paris green should be used,
and no more lime than directed.

Care must be taken in combining the arsenites with
other fungicide solutions, as one is liable thns to pro-
duce a compound very injurious to foliage. Paris green
or London purple added to simple solutions of copper
sulphate, or to ammonia compounds without lime, in-
jures foliage vastly more than in simple water mixture.

COST OF FUNGICIDE MATERIALS

The approximate wholesale and retail price of the
more important substances used for fungicides is indi-
cated below :

Wholesale. HHtiil.

Per lb. I'erlb.

Ammonia (22° lianme) $0.07 .IrO.^O

Carbonate of copper (Precipitated). .. .40 .60

Carbonate of ammonia 14 ••JO

Li ver of sulphur 15 .25

Lime, per barrel (300 pounds) 1.65

Soda carbonate 04 .10

Soda liypo-sulphite 06 .15

Sal soda 01 V* .05

Sulphate of copper (Powdered) 07 to .00 .12 to \o

Sulphate of copper (Crystals) 0,5 .10

Sulphur 03 .10

THE APPLICATION OF FUNGICIDES

Fungicides may be applied to plants, either in the
form of a dry powder or a liquid solution. In the for-
mer case they are usually most easily handled by means
of a powder bellows — such as Leggett's powder gun —

22

FUXGI AXD FUNGICIDES

and in tlie latter by means of some form of spraying

pump. In both cases it is important that they be finely

divided and evenly distributed.

There are many forms of spraying 2:)umps uj^on the

market. In general they are of four sorts : The bucket

l^umj^s, the knapsack
sprayers, the barrel spray-
ers, and the geared auto-
matic machines. The
form of tlie knapsack
sprayer is shown in Fig. 8.
It is useful in some cases,
but in general the carry-
ing of the reservoir and
contained liquid should
not be imposed on liuman
shoulders. A convenient
barrel outfit is shoAvn in
FIG. 8. KNAPSACK sPKAYER. ^jg. 9. The barrel has

upon it a double discharge pump, to which are attached
two lines of hose, provided Avith good nozzles, and fas-
tened at the end to poles. Three men oi3erate the ma-
chine, one driving and j^umping, and two directing the
spray.

Many different kinds of sj^ray nozzles are also offered
for sale. In several cases, at least, each has a peculiar
value for certain lines of work. Consequently the fruit-
grower who has a variety of vines and trees to spray
should own four or five nozzles, and use the one best
adapted to the work in hand. Some of the best forms
are the Improved Yermorel, Climax, Cyclone, Graduat-
ing Spray, Mason, and Improved McGowen, ]^o. 7.

Professor L. H. Bailey uses, for bushes and vines
which need to be sprayed on the under surface, the
cyclone nozzle, in connection with a home-made wheel-
barrow tank, as shown in Fig. 10. A piece of rubber

APPLICATION OF FUNGICIDES

23

tubing five or six feet long connects the nozzle with the
pump, the outer end of the tubing being tied to a light
rod, so that the spray can be sent wherever desired.

FIG. 9. THE CHESTEK SPKAYING CART.

FIG. 10. METHOD OF SPKAYIXG BUSHES.

A fuller discussion of the subject of spraying will
be found in the author's little manual entitled S])raying
Crops.

I^J^I^T I

Fungi affecting Orchard Fruits

CO

C
•A
U

n
<

a

Q
H

s
o

M

PQ

o
<

I-!
O

Oh

<

Ph

FUNGI AFFECTING THE APPLE

The Apple Scab

Fusicladium dendriticum

There is, jorobably, no fungous disease of fruits so
familiar to the general public as the apple scab, or, as it
is sometimes called, the black spot. This is due to a

fungus which produces the well-
known scabby spots upon the
fruit, and also attacks the leaves
and green shoots. It first ap-
pears upon the leaves in the
shape of smoky greenish spots,
more or less circular in outline.
Tliese gradually enlarge, and
frequently several of them run
together, so as to form good
sized blotches; as they grow
older their color darkens, finally
becoming almost black. The
upper surface of the leaf is usu-
ally affected.

Sometimes the fungus de-
ON A LEAF. velops SO rapidly on the expand-

ing leaves in early spring as to blight them, dwarfing
and killing the younger foliage. An instance of this,
observed by Professor L. II. Bailey, is illustrated in

27

FIG. 11. APPLE SCAB SPOTS

28

rUXGI AXD rUXGICIDES

Plate 11, which represents the size of dwarfed leaves late
in July, as compared with a full-grown one. In such
seasoDs the newly formed fruit is also attacked by the
fungus, which shrivels the young apples and causes
them to fall off. Occasionally an entire crop is thus
destroyed.

The spores, or reproductive bodies of the fungus,
are produced in immense numbers on the blackened
spots on the leaf and fruit, forming most abundantly dur-

FIG. 12. FRUIT AXD LEAF SPOTTED BY SCAB.

ing cool, wet weather. They are carried hither and
thither by wind and rain. When they light npon a
moist leaf or fruit they germinate, by sending out a
little tube, and thus form a new center of disease. The
spores pass the winter on the bark, twigs, and stored
fruit, as well as on the fallen leaves and fruit. During
the moist weather of spring they start the disease again.
Besides the injury to the leaves and the destruction
of the very vouno- fruit, this disease causes serious losses

THE APPLE SCAB

29

by dwarfing and disfiguring tlie apples that mature.
Secretary A. 0. Hammond, of the Illinois State Horti-
cultural Society, estimated the annual loss due to this
disease in Hlinois alone at $400,000, and other authori-
ties have estimated it at from one-sixth to one-half of
the entire crop.

The mycelium, or vegetative portion of the scab
fungus, consists of brown-
ish cells which develop
just beneath the skin of
the leaf or fruit, but, as a
rule, do not penetrate
deeply into the tissues.
After the fungus has
grown in this way for
some time it pushes out-
ward, rupturing the skin ;
and on the exposed sur-
face short vertical brown
threads ai^e developed, on
the tips of which the
small oval spores are pro-
duced (Fig. 14). When
mature the spores sepa-
rate, and are scattered by wind and rain in all directions.

Treatment. — In spring, just before the leaf-buds
open, spray thoroughly with dilute Bordeaux mixture,
or else sjiray before the leaf-buds begin to swell, with a
simple solution of copper sulphate ; repeat the applica-
tion of Bordeaux mixture a little later, just before the
blossoms open ; spray for tlie third time just after the
blossoms have fallen, adding arsenites for the codling
moth if desired ; ten da3^s after this third application
spray again with the combination of Bordeaux mixture
and Paris green or London purple. Do not aj^ply Bor-
deaux mixture late to early ripening apples.

FIG. 13. SCABBY APPLE SHOWING
RUPTUKES IX THE SKIN.

30

FUiTGI AKD rCKGICIDES

Literature. — Articles concerning apple scab may
be found in the following publications : Bulletin Ohio
Experiment Station, IV, No. 9 ; Report JJ. S. Dept.
Agriculture, 1887, pp. 341-347 ; First Eeport Wisconsin
Experiment Station, 1884, pp. 45-56; Cornell Univer-
sity Experiment Station, Bulletin 48.

The Powdery Mildew

Podosphcera oxyacanthce

About midsummer one may often find on the leayes
and young shoots of apple, cherry, quince, j^each, and

FIG. 14. SECTIOX SHOWIXG SCAB FUXGUS.

^, spores in position, as developed; B, skin of fruit turned up; C, parenchyma-
like cells of the parasite; Z» £>, tissues of the fruit. Much magnified.

several other trees, small round whitish blotches of mil-
dew, which at first have more or less of a radiated ap-
pearance, due to the spreading of the threads. In a
short time many of the spots enlarge so that they run

THE POWDERY MILDEW

31

toaetlier : and the mildew often covers the whole surface
of the leaf, either as a thin coating through which the
green surface can be seen, or as a thick, felt-like cover-
ing, which entirely conceals the leaf surface. This mil-
dew is composed of a great number of minute white
threads, branching in all directions, which form the
mycelium of the powdery mildew fungus. In the fungi
of this group the mycelium is external, t. e., instead of
developing on the inside of the leaf of the host-plant, it
develops on the outside, and in order to get nourishment

c d

FIG. 15. APPLE POWDERY MILDEW.

c, Mycelium forming summer spores; </, winter spore case (peritliecium). Magnified.

the mycelium threads send little suckers into the cells
of the leaf and absorb their contents, for the benefit of
the fungus. Soon after the mycelium gets well devel-
oped it assumes a powdery appearance, due to the pro-
duction of great numbers of the minute white spores,
called the summer spores, or conidia (Fig. 15 h). These
are very light, and are scattered by every breath of air.
When one of them falls upon an unaffected leaf, where
sufficient moisture is present, it germinates and starts
the disease anew. By means of these summer spores — a

3^ FUXGI AXD FUNGICIDES

yast number of which may develop from the mycelium
of a single leaf — the fungus is able to spread very rap-
idly. Toward the end of summer the mycelium devel-
ops small round black masses just visible to the naked
eye, which are the cases containing the winter spores.
These cases are technically called perithecia, and when
magnified resemble Fig. 15, d. They remain on the
leaves when the latter fall in autumn, and tide the fun-
gus over winter.

This powdery mildew may develop on either surface
of the leaf, aud is especially likely to appear on the
leaves and stems of j'oung shoots. It is also usually
much more almndant on young trees than old ones, and
is especially destructive to nursery stock ; so much so,
in fact, that wdiere no treatment with fungicides takes
2^1ace it often prevents the successful budding of a large
proportion of the young trees. Leaves severely attacked
by the fungus dro]:) off prematurely, and so prevent the
proper growth of the tree. The disease is usually most
prevalent during seasons of dry weather.

Treatment. — As a rule, it is only in the nursery
that this disease is sufficiently destructive to require
remedial treatment. To prevent it, spray with the am-
moniacal solution of copper carbonate, making the first
aj^plication when the leaves are about half-grown, and
repeating four or five times at intervals of twelve days.
Mr. B. T. Galloway has shown that nursery stock can
be sprayed with this solution five times, at a cost of
eight cents per thousand trees, estimating the copper
carbonate at forty cents per pound, and the ammonia
(26°) at eight cents per pound.

Literature. — An excellent general account of this
disease, by Mr. M. B. AYaite, may be found in the 1888
Eeport of the Department of Agriculture (pp. 352-357) ;
while notices of remedial experiments appear in bulletins
of the Division of Vegetable Pathology.

THE BITTEK liOT

33

The Bitter Rot, Ripe Rot, or Apple Rot

Glceosporium fructigenum

The Bitter Eot of apples, frequently called the Eipe
Rot, or simply the Apple Eot, is caused by a parasicic
fungus which most commonly attacks the fruit as it
approaches the ripening period, although it is said often
to attack the apples at any time after they are three- .
fourths of an inch in diam-
eter. The injury is most
likely first to appear at the
calyx or blossom end of the
fruit, but it may start any-
where upon the surface. It
gradually spreads from the \
point of infection through-
out the tissues, causing
brown and decayed spots as
it progresses. The larger fig. i6. apple affected by bit-
fruits usually fall to the ^^^^ ^""'^ yungvs, showing

•^ BLACK PUSTULES ON

ground, but many of the the skin.

smaller ones shrivel up and remain on the tree in a
mummified condition. Great quantities of spores are
developed on these withered ^^Miangers-on," and by
means of them the disease is started again the following
spring-. The fungus seems to be more destructive dur-
ing damp weather. Professor H. Garman expresses the
opinion that this disease causes greater loss in Kentucky
than any other enemy of the orchardist. ^^It is no
uncommon thino^ for three-fourths of all the fruit on a
tree to be rendered worthless by its attacks. In the
latter part of summer we find, in many orchards, the
ground covered with well grown apples, suitable for mar-
keting, as far as size and maturity are concerned, yet
3

34:

rUXGI AXD FUNGICIDES

not worth gathering up because of the rot with which
they are wholly or in part affected/' Other southern
states suffer equally serious losses. One orchard in
Arkansas has been rej^orted in which, in 1887, tlie attack
of the funsfus was so severe that seventv-fiye trees ^^elded
less than twenty-fiye bushels of fruit. A photographic
view of one of the depressed rotten spots as it appears on
the maturing fruit is shown in Fig. 17.

This disease is distinguished after it has become
well established by the jDresence of small blackish pus-

no. 17. APPLE SHOWrXG ROT SPOT.

tules scattered oyer the surface of the apple. These are
the fruitinor spots of the funsrus. The mycelium which
has penetrated the pulpy tissue of the fruit in all direc-
tions, disorganizing it and causing the rot, here develops
a large number of cells, which rupture the skin of the
apple and produce the spores at the tips of slender pro-

THE BITTER ROT 35

jecting threads. These spores are blown off by the
wind, or washed downward by rain. When one of them
lodges u2)on another apple, where sufficient heat and
moisture is present, it germinates by sending out a little
tube, and may thus start the disease in a new situation.
If the mycelium of the fungus running through the
apple is carefully examined, one will see at frequent
interyals on the threads small spore-like bunches, simi-
lar to those shown in B, Fig. 19. From these other
mycelium threads may start. In the same figure a ger-

FIG. 18. SECTION OF PUSTULE.

A, Mass of fuugus threads and cells; B, spore-bearing threads; C C, skin of apple

ruptured by the fungus.

minating summer spore is seen in C, and one of the pus-
tules already referred to in A.

This same fungus attacks grapes, and Dr. Halstead
has recently found that it will develop upon pears,
peaches, egg plants and i")eppers. Consequently it seems
to have a wide range of hosts, and general clean culture
is evidently important as a method of preventing its
injuries.

Treatment. — The first step toward the successful
prevention of this disease is the removal and burning of
the mummied apples on the trees. This should be done
during winter. It would be desirable, also, to rake up
and burn, or bury, the fallen fruit and surrounding rub-

3G

FUXGI AXD FUXGICIDES

bish. Then the Bordeaux mixture treatment recom-
mended for the preyention of apple scab will have a
decided influence in lessening the amount of damage.

An account of experiments with this disease may be
found in Bulletin No. 44 of the Kentucky Agricultural
Experiment Station ; and of its nature in the 18S9 report
of the same station. It is also discussed in the 1887
Report of the IT. S. Dej^artment of Agriculture, and
more fully in the Journal of Mycology, v. VI, p. 164.

The Apple Rust

Gymnosporangium and Rcestelia

A peculiarity of many parasitic fungi is that the
complete cycle of their existence is not passed upon a
single host-plant, but that, instead, one jihase of devel-

FIG. 19. ^, surface view of pustiile; if, mycelium thread; (J, ^terminating spore.

Magnified.

opment occurs upon one plant, whiJe another quite differ-
ent stage of existence is passed on an entirely different
host. A striking illustration of this is seen in the case of
the rusts which sometimes affect apple trees, causing the
leaves to become more or less blistered with orange-yel-
low spots. In this disease the fungus on the apple is an
alternating form arising from spores produced by the so-
called ''^ cedar -ap23les," or ^' cedar-balls" of cedar or juni-

^"»~!!vi'''''

I'LATK Tir. CEDAR appTjES {Gytn,nosx)oranrfuim clavipes).

38

FUXGI AND FUXGICIDES

per. The presence of tlie fungus causes a peculiar
develoj^ment of the cedar leaves, as may be seen by ref-
erence to Plate III, wliere a normal healthy cedar branch
is shown at B, and a diseased one at A. The affected
branch not only has the ^'apples" developed, but the
leaves are entirely changed in shape. Reproductive
spores are produced from these ^'apples;" they ger-
minate in a way illustrated at C, and are blown about by
the wind. AVhen one is carried to an apple leaf where
conditions favorable to germination are present, it may

2.

FIO. 20. APPLE KUST.
1, Cluster cups on under surface of leaf; 2, spores; 3, spores germinating.

develop and produce the aj^ple rust. The affected aj^j^le
loaf has scurfy bunches on the under surface, the area
on the upper surface above these becoming orange-yel-
low, or sometimes almost crimson, in color. As the
disease progresses the leaf becomes more and more dis-
torted, and in case the injury affects a large proportion
of the leaves serious damage to the tree may result.

The spores are produced in great numbers on the
orange-yellow areas of the aj^ple leaf, and are blown

THE APPLE TWIG BLIGHT 39

iiwaj by the wind. Tliose which light upon red cedar,
under favorable conditions, may develop, and by so
doing carry the disease back to the original host plant.
Thus there is a continual alternation of the generations
of the funous.

The form of the fungus which occurs upon apples is
commonly called the Rmstelia form. Besides the dis-
colored areas on the upper surface of the leaf, the pecu-
liar ^^cluster-cups" of the fungus are developed on the
under surface. A group of these is represented in Fig.
20. The ^^cups" are usually about a quarter of an inch
in diameter. In them the chocolate brown spores are
developed ; some of these are seen in 2, where the thin
places in the wall through which the germinating tubes
are to develop are seen at a, while in 3 some germinating
spores arc rci)resented.

Treatment. — The knowledge of the fact that one
essential stage of the fungus is passed upon red cedar,
leads to the suggestion that, in a given region, the injury
to apples may be prevented by destroying the red cedars.
It is probable that spraying orchards wdth fungicides for
scab, or other diseases, will also assist in preventing
the rust.

Literature. — Dr. B. D. Halstead has published an
excellent general discussion of the relations of apple
rusts and cedar apples, in the 1888 Report of the De-
partment of Agriculture (pp. 370-381). Professor A. B.
Seymour has also treated of them in the Transactions of
the American Horticultural Society (v. IV, p. 152), and
Dr. E. Thaxter, in the 1891 Report of the Connecticut
Experiment Station.

The Apple Twig Blight

Micrococcus amylovorus

The twigs of apple trees, together with the leaves,
flowers or fruit which thev bear, often turn brown or

Sprayed. VnsiJrayed.

PLATE IV. PEAJl LEAF-BLIGHT EXPEKIMENT.

THE PEAR LEAF-BLIGHT

41

black, and die, in a manner similar to that of jiear twigs
affected by pear bliglit. Such injuries to apple are com-
monly called 'Hwig blight,'' or ''fire blight." They
are, however, due to the same germs as the pear blight,
discussed on a later page under the pear. Cutting off
and burning affected twigs is the best remedial measure.

FUNGI AFFECTING THE PEAR

The Pear Leaf=blight

Entomosporium maculatum

This is probably the most generally destructive fun-
gous disease to wdiich the i^ear is subject. It appears
early in spring, soon after the leaves develop, usually

revealing its presence at
first by minute, dull red-
dish spots on the upper sur-
face of the leaf. A little
later the spots appear on
the lower surface also, and
the reddish tint gives way
to brown, with a darker
center. As the fungus de-
velops the spots enlarge, in-
volving more and more of
the tissues of the leaf, until
the tissues directly affected
within the spots, and those
indirectly affected between, include nearly or quite the
entire leaf, which appears sere and brown. Very young
leaves sometimes curl up, as a result of the attack. The
quince is also injured by this fungus, an infested leaf
being represented in Fig. 21. When leaves are badly

FIG. 21.

QUINCE LEAF SHOWING
LEAF-BLIGHT.

PLATE V. PEAKS INJURED BY LEAF-BLIGHT FUNGUS.

THE PEAR LEA F-B LIGHT

43

injured tliey fall ofp, and whole orchards arc some times
defoliated by the disease, the trees appearing as bare in
midsLimmer as they normally do in winter (Plate I\^,
iinsprayed). Of course, the effect upon the tree is very
injurious ; it is unable to store up the materials of
growth properly, and it becomes weak and impoverished.
But this fungus does not confine its attention to
the foliage ; the stems and fruit are also attacked. The
former become blackish and dead, and the latter is at
first covered with reddish pimples, which finally become
blackened and roughened, and generally cause the pear
to crack open in such a manner as to ruin the fruit.
Several such pears, photographed by Dr. II. H. Lamson,
are represented in Plate V.

This disease is especially destructive to young pear
trees in the nursery, and the defoliation caused by it
quite generally prevents successful budding, unless pre-
ventive treatment is given. A good general account of
the fungus occurs in the 1888 report of the Department
of Agriculture.

The little black dots in the centers of the spots con-
sist of the fruit of the fungus. If a vertical section be
made of one of these and it be placed under the micro-
scope, it will be seen that the pecu-
liar two- to six-celled spores shown in
Fig. 21 are borne upon short stalks
coming from the mycelium in the
leaf cells. These spores germinate
under favorable conditions, sending
out a tube which burrows its way
into the tissues of the leaf, and starts
the fungus again. These spores are
the conidia, or summer spores. Other
spores — the so-called winter spores —
are said, by some botanists, to be found among the
fallen leaves.

FIG. 22. PEAR LEAF-
BLIGHT SPORES.
MAGNIFIED.

•iJ: FUXGI AXD FUXGICIDES

Treatment. — Spray with the aramoniacal solution
of carbonate of copper as soon as leaves begin to unfold,
and repeat application two or three times at intervals of
two weeks; or the dilute Bordeaux mixture ma}^ be
used, spraying in the same manner as recommended for
apple scab. The effect of treatment with the Bordeaux
mixture, as shown in one of Mr. Galloway's experiments,
is illustrated in Plate IV. Discontinue the treatment
before the fruit is half grown.

The Pear Blight

Micrococcus amylovorus

The literature of American horticulture during the
present century contains frequent references to the per-
plexing malady called pear blight. Until recently there
were innumerable theories as to the cause and cure of
the disease ; but now, thanks to the investigations of
Professors Burrill and Arthur, we know that it is due to
the presence of a specific germ — one of the bacteria— so
minute as to require the aid of a powerful microscope to
sec it.

Pear blight is easily distiniruished from other mala-
dies. Limbs affected by it become dead and blackened,
tosrether with the leaves, dowsers or fruit which they
bear. The injury may be confined to one or a few limbs,
or may gradually extend to the whole tree. The twigs
of apples and certain other ^^o^^i^'iceoas fruits are also
liable to the disease.

The germs of pear blight are so minute that they
are carried through the air by the slightest wind. They
seem to be unable to penetrate healthy bark, but gain
access to the interior of the tree throusfh the blossoms.
They light upon the sticky surface of the inside of the
flower cup, and are able to begin developing there, pass-
iuor down throuo^h the stem to the twis^ below. The

THE PEAR BLIGHT -io

germs can also gain access tlirongli the tips of growing
branches where the green growth is soft and succulent,
and, no douljt, they occasionally enter through cracks
in the bark.

After the bacteria have gained access to the tissues
of the tree they multiply rapidly, and generally in the
course of a few weeks have become so abundant as to
show their presence by blackening the bark or blossoms.
^'As the disease progresses/' says Professor Arthur,
^^the germs exude on the surface, and the gummy sub-
stance thus produced is washed off ; the gum is dissolved
and the germs set free and washed into the ground.
The germs multiply there in rich mold and grow all
winter, or year after year. In a dry time the wind takes
up the germs into the air, or they may be taken up by
.simple evaporation. Xow when the surface of the tis-
sues is tender and moist, as in spring, the air, laden
with these germs, i)laying over the trees, brings the
germs in contact with the delicate tissues. The germs
are held there by the moisture and enabled to grow; the
disease gets a foothold, and in the course of a month or
two it shows itself by the sudden blackening of the
leaves." Insects also carry the germs to blossoms.

Treatment.— No successful method of preventing
the disease by artificial applications to the trees has yet
been found. But it has been shown that if the trees are
carefully watched during the season of growth, and the
affected twigs cut off (at least a foot below the lowest
point of injury) and burned, the damage done may be
greatly lessened. Professor Burrill advises the examina-
tion of the trees once a fortnio'ht, and states that the
bark reveals the damage best after a shower, when the
surface is wet. It is important, also, to keep the bark
free from wounds.

The fact that slow growing pear trees are less liable
to injury by blight than those of rapid growth has long

46 rUXGI AXD FUNGICIDES

been noticed. Consequently, such cultural methods as
will tend to produce a slow, steady growth are to be
adopted.

Literature. — The really valuable publications con-
cerning pear bhght date from Professor Burrill's an-
nouncement of the genuine cause in 1880. His articles
may be found in the following publications : Transac-
tioQS Illinois State Horticultural Society, 1880, pp. 157-
167 ; 1883, jip. 40-49 ; Report American Pomological
Society, 1880 ; Report Trustees Illinois Industrial Uiii-
versity, 1880; Transactions Illinois Department of Ag-
riculture, 1880, pp. 433-436. Professor J. C. Arthur
has also published a number of valuable papers. A sum-
mary of his results may be found in the Report II. S.
Department of Agriculture, 188G, pp. 125-129 ; Re^oort
of the American Pomological Society, 1885 ; and Report
of the Michigan Horticultural Society, 1885, pp. 173-177.
More recently Mr. M. B. Waite has been investigating
the disease. His results may be looked for in the publi-
cations of the Division of Vegetable Pathology.

The Pear Scab

Fusicladiuni pyrinum

This disease is very similar to apple scab, the fun-
gus, in fact, being believed by many botanists to be the
same species. At any rate, the chief points in the life-
history and remedial treatment are the same as for the
apple disease.

Care should be taken not to apply the Bordeaux
mixture too late in the season. Early varieties should
have but one spraying with this mixture after the fruit
^'sets," and late varieties but two. Where additional
applications are needed, use the copper carbonate solution.

FUNGI AFFECTING THE QUINCE

The Leaf=blight and Fruit=spot

Entomosporium maculatum

The leaves of quinces often become dotted with
small round brown spots, resembling Fig. 23, which

gradually become more numerous,
and may finally run together to
form large blotches, as shown in
Fig. 21 (p. 41), inyolving, occa-
sionally, the whole leaf, and caus-
ing the premature dropping of
the foliage. This is the same

fungus that causes the leaf-blight
of the pear, and the main points
in its development have already
been described (pp. 41-44).
Quince fruit, as well as foliage, is
attacked by it, the effect on the
FIG. 23. QUINCE LEAF-BLIGHT fl.^it bclug secniu small brown,
or blackish spots which appear on the surface, and have
given the disease the name of fruit-spot. Several of
these spots frequently run together, and sometimes a
large part of the surface becomes affected. The fungus
dwarfs the fruit, and renders it less salable. The defo-
liation of the trees, of course, greatly reduces their
vitality. Young quince trees in the nursery are espe-
cially liable to injury by this disease, as it causes the

47

48

FU^s^GI AXD FUXGICIDES

leaves to fall off during summer, and so i^revents the
growth necessary for successful grafting.

Treatment. — The treatment recommended for the
pear (p. 44) is equally applicable to this fruit. The
benefits of spraying with the Bordeaux mixture were

FIG. 24. YOUXG QUINCES INJURED BY KUST.

illustrated in a striking manner, by the results of some
experiments made at the Connecticut AgricuUural Exper-
iment Station by Dr. Koland Thaxter. The sprayed rows
had been treated both that season and the previous one,
and so the year before had had an opportunity to store up

THE QUiXCE KLST

40

nourishment for fruit production. Three applications
were made, the first May 11, the second May 28, and
the third June 22. Two sprayed rows yielded seventy-
one and one-half baskets of marketable fruit, while five
untreated rows yielded one basket of marketable fruit.
^^ Comparing the yield from the untreated rows, and
estimating it at one-third basket per row, which is more
than was actually obtained, the net income from a single
treated row was one hundred times as great as from an
untreated row.''

The Quince Rust

Roestelia aurantiaca

Young quinces are sometimes disfigured by the
presence of a rust fungus, in the peculiar way repre-

senterl in Fig. 24. On some per-
son of the distorted surface orange
spots eventually appear ; they are
usually more or less elevated. From
them the spores of the fungus are
produced in immense numbers, to
be borne hither and thither by the
wind. A peculiar fact concerning
these spores is that they do not de-
velop on the leaves and fruit of
other quinces, but, instead, are
only able to develop upon the
branches of red cedar and low jun-
ipei*. Those spores which are
blown to these plants under favor-
able conditions, j^roduce on them the ^^ cedar balls," or
^^ cedar apples/' so often noticed. One of these is repre-
sented in Fig. 25. On the cedar or juniper other spores
are produced, for the wind to carry back to quince to
start the rust as^ain. Thus there is constantly what is

FKJ. 25. CEDAR BALL.

50 FUXGI AXD FUXGICIDES

known as an alternation of the generations of the fun-
gus, and two entirely different plants are required for
its continued growth.

This rust is very similar to that which occurs upon
the apple, discussed on a previous page. One important
preventive measure consists in the destruction of cedars
and junipers ; and, probably, spraying with fungicides
will prove to be another.

The Black Rot

SpliCEropsis tnalorum

The fruit of the quince is subject to injury by sev-
eral fungi which cause rot. ^ The ripe rot of apples due
to GlcBosporium fructigenum often attacks them ; a
species of Phoma causes what has been called the '^^pale
rot," and other fungi occasionally induce decay. The
most destructive of these fruit diseases, however, is the
black rot, which usually fir.st appears upon the fruit
when it is half grown, or larger, in the guise of a small
brownish spot on the surface, generally at the blossom
end. The spot increases in size rapidly, and blackish
pimj^les soon appear; later the skin ruptures at these
pimples, and the spores of the fungus escape, to be dis-
tributed by the wind. The infested fruit often becomes
mummified, and may remain on the bushes over winter.
This fungus also attacks apple and other pomaceous
fruits. Quince orchards in the vicinity of apple or pear
trees are liable to infestation from them, and vice versa.

While it is probable that the use of fungicides will
prevent this disease, it usually appears so near the time
of harvest that their application may not be advisable.
Diseases of this kind may be prevented, to a considerable
extent, at least, by clean culture, — the destruction of
the rotting or mummified fruits, by means of which the
disease is propagated. This may often be supplemented

THE TWIG BLIGHT 51

to advantage by comparatively late spraying with the
ammoniacal solution of copper carbonate.

An illustrated account of this and other quince fruit
rots will be found in Bulletin 91 of the New Jersey Ex-
periment Station.

The Twig Blight

Micrococcus amylovoims

Quinces are sometimes attacked by the "fire blight,"
or "blight" of the pear, discussed on Pages 44 to 46.
Branches so attacked turn black and are easily distin-
guished. Cutting and burning, as recommended for
the pear, are the best remedial measures.

PLATE VI. BRANCHES OF YOUNG PLUM TREE AFFECTED BY BLACK

KNOT.

FUNGI AFFECTING THE PLUM

The Black Knot

Plowrightia morbosa

No fungous disease of fruits is easier to recognize
than this ; the black, wart-like excrescences upon the
twigs and branches of plum and cherry trees are too
well known to the majority of fruit growers. In many
of the older settled portions of the country the disease
prevails to such an extent, that it has led to the practi-
cal abandonment of the culture of these fruits ; and a
similar condition is threatened in other localities unless
preventive measures are vigorously applied. The fun-
gus attacks nearly all varieties of wild and cultivated
plums, and most varieties of cherries.

During the earlier years of the present century there
was much discussion concerning the cause of black knot.
Some horticulturists contended that it was due to in-
sects ; some that it was a constitutional affection of the
trees ; and some that it was due to fungi. The latter
proved the correct supposition, the life-history of the
fungus having been first worked out in 1875 by Dr.
W. G. Farlow. Like other fungi, this one reproduces
by means of spores. The knots first appear as swollen
places on the twigs ; as the swelling increases the bark
cracks open longitudinally, and the fungus produces
quantities of spores within these cracks, making them
appear as if covered with a velvety olive coating. These
are the summer spores ; they are blown through the air
by wind, and washed from twig to twig by rain ; those

53

54 FUXGI AXD FUNGICIDES

that lodge upon the tender bark of young shoots send
out germinating tubes and start other knots.

^'^As the season advances," says l)r. Halsted, '^the
young knots and the fresh growth of older ones lose
their olive, velvety appearance, turn a dark color, and

develop a hard incrusta-

/a ^^^. ti on on the surface. With-

.^^/"qQ ^ (P ^^ ^^^^ substance oi this

^^ ^i®*^ % black and brittle layer

^ © I %^ many spherical pits are

oQ ^^^Ic^.^ i p formed, and, as winter

g«e 3^Q p^ '^^•3^ #^^^ K advances, minute sacs are

^ W^'/*^ Q^ .^o'^*/?l'^"* produced upon the wall of

00^ % ^^ the cavity, that toward

J ^^ ^ spring bear each eight

^ ^ oval bodies that are known

FIG. 26. SPORES OF BROWN ROT. ^s sac sporcs. Thcsc
MAGNIFIED. cscapc from their long

sacs and pass out through a pore at the top of the cav-
ity, and are then carried by the winds to the surface of
a young cherry or plum
twig, and thus begin
another knot, which, in
the course of time, pro-
duces a new crop of sum-
mer, and another of winter
spores, and thus the dis-
ease is preserved and
propagated." fig. 27. brown rot spores ger-

Treatment.-Theonly ^"nating. magnified.

successful treatment for a badly infested tree is to cut
and burn it, trunk, branch and all. All knots on trees
but little affected should be cut and hurned. Never
throw the removed knots on the ground, as spores are
developed off as well as on the tree. When young
knots appear on large limbs, or on limbs that one does

THE BLACK KJ^OT

55

not wish to remove, it is believed that painting them
with a mixture of red oxide of iron in linseed oil will
destroy them. Probably an application of the Bordeaux
mixture would prove equally effective. All trees liable
to injury by this disease should be examined at frequent
intervals, and any signs of forming knots be at once
removed.

Concerted action is necessary among all the fruit
growers of a neighborhood, if the disease is to be stamped
oat. Local horticultural societies should agitate the
matter and create a public opinion that will render it

FIG. 28. PLUMS AFFECTED BY BKOWN ROT.

uncomfortable for any one to allow the knots to remain
on his trees as a source of contamination for his neigh-
bors' orchards. In some states la\^s have been enacted
compelling tlie destruction of the knots. Wild cherry
trees should be included in the examination for diseased
trees.

Literature. — Dr. Farlow's article was published
about 1875, in the Bulletin of the Bussy Institute. An

56

FUXGI AXD rUXGICIDES

excellent popular account of the disease, by Dr. Hal-
sted, aj^pears in Bulletin 78 of the New Jersey Experi-
ment Station. There are many other short accounts
scattered through our horticultural literature.

The Brown Rot

Monilia fructigena

The brown rot of stone fruits is probably familiar to
every grower of plums, peaches or cherries in the older
portions of the United
States. It is one of the
most destructive fungous
diseases of fruits, attack-
ing not only the fruit
itself, but also the twigs,
leaves and blossoms. It
is occasionally found upon
the apple and pear, but in
the Northern States is
seldom destructive to fig. 29. browx kot. imagnified.

these fruits, although jn "'CHams of spores; 6, branching myceUum.

some southern localities it is reported to do serious dam-
age. The annual cycle of the fungus of brown rot may
))e briefly outlined as follows, starting with its attack
upon the fruit : A minute spore (Fig. 26) falls upon a
green plum on which there is a little water, left by rain
or dew, and sends out a germinating tube which pene-
trates the skin of the fruit. Once inside it grows rap-
idly, pushing its branches through the pulp in all direc-
tions, and thus forming a dense mass of mycelium,
which absorbs the contents of the cells, disorganizing
the tissues and causing the so-called rot. The affected
plum at first turns brown in one or two spots; these
gradually enlarge until, finally, the whole plum becomes
brown and *^ rotten." When it has reached this stage it

a

FIG.

THE BROWX ROT

57

soon becomes covered with a brownish, or ash-colored
velvety coating, which consists of vast numbers of mi-
nute spores produced by the mycelium of the fungus.
If one of these velvety masses be shaken over a glass
'^ slide," and the slide be put under the microscope, it
will be seen that a great many of the spores have sepa-
rated and fallen off, as shown in Fig. 26. The spores
are blown about by the wind, and when one of them
lodges on an unaffected plum where sufficient moisture is

FIG. 30. MUMMIED PLUMS.

present it starts the disease again. The rotten plums
continue hanging upon the tree, gradually shriveling up
(Fig. 28), until finally they become dry and mummied
husks, roughened by ridges of the skin, and in this state
they remain on the trees through the winter (Fig. 30).
On many of these mummied plums some spores will
adhere, even until the following spring, when they -ap-
parently have the power of germinating ; and in all, or
nearly all, of them the mycelium remains in a dormant

58 fu:n'gi and euxgicides

condition, so that during the warm, damp weather of
early spring this mycelium is able to produce a new crop
of spores. These spores are scattered everywhere, and
many of them develop in the blossoms and young leaves.
Serious losses are sometimes occasioned bv this kind of
injury to the blossoms. As soon as the fruit is well
formed it also may be attacked.

Treatment. — The first essential to success in pre-
venting this disease is to pick off and burn, as early in
winter as possible, all mummied plums hanging upon the
trees ; and the spraying treatment recommended below
should also be supplemented by an occasional inspection
of the bearing trees, and the removal and burning of
such rotting plums as may be seen. The most success-
ful results so far obtained in spraying for this disease,
have followed the use of the dilute Bordeaux mixture
and the ammoniacal solution of carbonate of copper,
especially the former. Sj^ray first before the blossoms
open ; then as soon as the fruit is well formed spray
again, and repeat the application twice later at intervals
of two weeks. If the Bordeaux mixture is used, Paris
green may be added for the earlier sprayings, to destroy
the curculio at the same time.

Literature. — One of the first general accounts of
this disease was published in 1885, by Professor J. C.
Arthur, in the Fourth Report of the Xew York Agri-
cultnral Experiment Station. This was followed, in
1888, by an extended article, illustrated by two excellent
plates, by Mr. B. T. Galloway, in the Report of the
United States Department of Agriculture for that j^ear
(p. 319-352) ; and since then Dr. Erwin F. Smith has
contributed to the Journal of Mycology (v. V, p. 123 ;
V. VII, p. 3G) some valuable additional information.
Professor J. E. Humphrey has also published a popular
account of the disease in the Eighth Eeport of the Massa-
chusetts Agricultural Experiment Station.

X'l.ATlC \ 1. J'MM I'OC'KETS.

60 FUNGI AXD FUNGICIDES

Plum Pockets

Taphrina pruni

Although this remarkable disease has been known
for many years (having, indeed, been described as early
as 1593), its real cause has been recognized only compar-
atively recently. It was formerly supposed to result
from the attacks of insects, or from improper fertiliza-
tion of the ovule ; but it is now known to be due to the
growth of a fungus.

Mr. Galloway states that ^'the 'pockets' (Plate \1)
make their appearance soon after the flowers have fallen,
attain full size and drop from the trees toward the mid-
dle or last of June. At first they are more or less glob-
ular in shape, but as they grow older they become
oblong, or oval, and frequently more or less curved.
They vary in size, but, as a rule, are from one to two
inches in length, and from one-half to one inch in diam-
eter. When young they are nearly smooth, and can be
distinguished from the healthy fruit by their pale yellow
or reddish color. As they grow older the color changes
to gray, the surface appearing as though it had been
sprinkled with fine powder, and at the same time the
pockets become wrinkled. Finally they turn black, or
dark brown, and rattle like bladders when brought in
contact with any hard substance. They remain on the
tree in this condition for two or three days, then fall to
the ground and perish. Sections through the diseased
fruit show that the walls are quite thick, and that in
place of a stone there is a large cavity filled with fun-
gous threads and air."

The leaves and young branches are also sometimes
attacked by the fungus; both become swollen and dis-
torted. AVhen a tree once begins to bear the pockets it
usually continues bearing them during following seasons,
unless vigorously pruned. The red and jourple varieties

PLUX POCKETS

61

are the ones most often attacked, but all kinds are liable
to injury ; and the fungus is occasionally found upon
wild cherries.

The mycelium of this fungus consists of numerous
colorless threads which ramify through the tissues of
the young fruit. A special development of these threads
occurs just beneath the outer skin (cuticle), and from
this there are sent upward numbers of short cylindrical
bodies (Fig. 31 a), wliich finally burst through the skin
and grow till quite long, as seen at b, being filled with a

FIG. 31. PI>UM POCKET FUNGUS. MAGNIFIED.

granular matter. Tlien a transverse i^artition is pro-
duced a short distance from the upper end, and the
granular matter gathers itself together in six or eight
little spores (6-). These spores finally escape from the
cell in which they are held, and, under favorable condi-
tions, germinate. In so doing each of the spores pro-
duces on one side a bud having a shape similar to the
spore itself; this bud produces another bud, and this
another, until the substance of the original spore is
exhausted. But botanists have not yet been able to
infect healthy plums with these spores or their buds.

62

FUXGl AXD FUXGICIDES

The mycelium of the fungus also winters over in the
tips of the young branches.

Treatment. — A yigorous pruning of all affected
branches some distance from the tips, in order to remove
the mycelium in the tissues, seems to be the most prac-
ticable remedial measure. The joockets should, of
course, be removed before maturing, and the safest way
will be to burn all the material so cut off.

Literature. — The best article upon this subject so
far, i^ublished in America, occurs in the United States
Department of Agriculture Report for 1888 (pp.
366-369).

The Plum Fruit=scab

Cladosporium carpophilum

In Iowa and some other localities a comparatively
little known disease has recently been noticed on native

a he

FIG. 32. PLUM DISEASES.
a, b. Fruit scab ; c, f I'uit spot.

plums. It appears when the fruit is ripening, in the
shape of minute round specks, of a paler or grayer color
than the surrounding skin. These usually enlarge as
the fruit ripens, finally attaining a diameter of a quarter,
or even half an inch. Several spots sometimes run
together to form a blotch. The mycelium of the fungus

THE PLUM LEAF-BLIGHT 63

does not j)enetrate deeply into the fruit, and in itself
the disease visually causes little direct damage ; but indi-
rectly it is often injurious, by making cracks in the skin
through which the spores of other fungi get entrance to
the pulp of the fruit. Presumably spraying with Bor-
deaux mixture will have a preventive effect upon it.

THE PLUM FRUIT-SPOT

Professor L. H. Bailey has called attention to a
fruit spot affecting certain native varieties of plums in
the south (Fig. 32 c). It is caused by a species of
Phoma, and is believed to be allied to the black rot of
the grape, and to be controlled by the Bordeaux mixture.

The Plum Leaf=blight

Cylindrosporium padi

The leaves of plum and cherry trees are often at-
tacked by a fungus which produces a blight that some-
times becomes very destructive, causing whole orchards
to drop their foliage prematurely, and thus interfering
with the normal development of the trees. Small dis-
colored spots, generally of a purj^lish hue, are the first
indications shown bv the leaves, of the attack. In a
short time these spots turn brown, the tissues being
destroyed, and later the leaves become yellow, while
many of the affected areas separate from the surround-
ing portion of the leaf and drop to the ground, leaving
holes, which have given the disease the name of ^^ shot-
hole fungus." It is also called the leaf-spot disease.
Under a lens the brown spots show a few black dots,
where the rei^roductive spores are developing. The
fungus is believed to live over winter on and in the
fallen leaves.

Some confusion exists in horticultural and myco-
logical literature concerning the nomenclature of this

64

FTTXGI AXt) FUXGICIDES

disease. Various names of funai have been used in
counection with it, one of the commonest being Septoria
cerasina. The name printed above is the one now
accepted by botanists.

The leaf-blight is especially destructive in the nur-
sery, the young trees often
being defoliated before the
middle of August. Bear-
ing plum trees also lose
their leaves prematurely
on account of it.

Treatment. — Exper-
iments conducted on an
extensive scale by the Ohio
Exj^eriment Station show
that in the orchard this
disease may be prevented
by spraying with dikite
Bordeaux mixture. Two
or three sprayings early in
the season are deemed suflB-
cient. It should not be
used too late, on account
of the liability of the mix-
ture to remain on the
ripened frait. In the nur-
sery the Bordeaux mixture
is also a preventive ; the
results of its use are well
represented in Fig. 34, re-
duced from i)hotographic
views of experiments conducted by the Division of
Vegetable Pathology.

Literature. — This disease has frequently been dis-
cussed in our horticultural literature, although very
little of yalue concerning remedies has been published

FIG. 3.3. DISEASED PLUM LEAF.

THE PLUM LEAF-RUST

65

until quite recently. An account of the Ohio experiments
mentioned above will be found in the Bulletin of the
Ohio Experiment Station for December, 1891 (v. lY,
pp. 216-217), and of the nursery experiments in the
Journal of Mycology {v. VII, No. 3).

FIG. 34. SPRAYIXG FOR PLUM LEAF-BT.IGHT.

The Plum Leaf = rust '

Puccinia j^^uni-spinoscB
This is a disease somewhat similar to the last.
Leaves affected by it become spotted with reddish above,
and yellowish-brown below, and when the attack is se-
vere the trees may be defoliated. The remedial treat-
ment is the same as for the leaf -blight.

FUNGI AFFECTING THE CHERRY

The Brown Rot

Monilia fructigena

As stated on page 56, where this disease is discussed

in its relations to the plum,
it frequently attacks cher-
ries, as well as jDlums and
peaches. Its life-history on
the cherry does not differ
materially from that on the
]3lum, although it usually
does not pass from fruit to
fruit so often on the cherry,
because the individual fruits
do not touch each other so
much. Fig. 35 represents a
sound ripe cherry, together
with one mummiiied by this
disease.

FIG. 35. DISEASED AND SOUND
CHERRY.

The Black Knot

Plowrightia morhosa
This disease is often as destructive to cherries as to
plums, under which it has already been discussed
Qop. 53-55). The account of its life-history and the
means of exterminating it there given applies with equal
force when it affects the present fruit.

The fungus which causes plum leaf-blight also
attacks the cherry, and frequently does great injury.

66

FUNGI AFFECTING THE PEACH

The Peach Leaf=curl

Taphrina deformans

It often happens that in spring, soon after the
leaves begin to expand, the foliage of peach trees be-
comes curled and misshapen. The
leaves are usually thickened and
discolored, and fall off in a short
time. All the branches may be
attacked, or the injury may be
confined to only a part of the tree.
AYhen the disease is severe the
young fruits fall off, and the crop
for the year is destroyed. The
defoliated trees soon push out a
uew set of leaves, but too late to
repair the damage done to the
fruit crop.

This leaf-curl is most injuri-
ous during wet springs. It often
ruins the peach crop over large
areas. It is uncertain in its
attacks, and comparatively little
is known of tlie life-history of the
fun o us which causes it.

If a thin section of one of the
swollen leaves be placed under a
high power of the microscoi^e, the
FIG. 36. TEACH LEAF-CURL, threads of thc myccliiim of the
fungus can be seen between the leaf cells, and sometimes
extending through them. The mycelium is most abund-

67

68 FUXGI A^s'D FUNGICIDES

ant just beneath the outer skin, and it pushes out
through the skin numerous "spore-sacs," each contain-
ing a half dozen or more spores. These spores are sup-
posed to spread the disease to other peach leaves, but as
stated above, very little is known of the life-history of
this fungus.

Treatment. — Xo practical remedy for this disease
has yet been found. The removal and burning of dis-
eased leaves, whether on the tree or ground, is commonly
recommended ; and spraying the trees early in spring,
before the leaves expand, with some of the fungicides,
has been suggested. The latter method is worthy of
trial.

Literature. — The peach leaf-curl is very frequently
mentioned in our horticultural literature, but few im-
portant articles concerning it have been published. The
best popular discussion that has come to my notice is in
Professor Lamson-Scribner's excellent little volume on
the ** Fungus Diseases of the Grape and Other Plants"
(pp. 12G-131).

The Peach Yellows

The peculiar affection of peach trees called the
'* yellows," has been known to occur in America for at
least a century, and during that time it has ravaged
many of the fairest orchards of the country. Although
most commonly affecting peaches, it also occurs in nec-
tarines, almonds and apricots.

No disease of fruits has proved so difficult to investi-
gate as this. Until very recently there were numberless
theories as to its cause, but the investigations of Dr.
Erwin F. Smith, to whom we are indebted for much of
the positive knowledge now possessed concerning it,
indicate that it is a germ disease, due, probably, to some
obscure bacterium-like organism.

h3
fcH

>

ft)

>

a

o

w

>
ft)
o

Ed

ftl
o

w

ftl

o

CO

70 FUNGI AXD rUi^GICIDES

Peach yellows now occurs over a large portion of
the States east of the Mississippi Eiver. During recent
years it has destroyed thousands of trees in Michigan,
Maryland, Delaware, New Jersey and New York.

Symptoms. — According to Dr. Smith, ^Hhe earli-
est unmistakable symptom of the yellows is the prema-
ture ripening of the fruit. Diseased trees ripen their
fruit, in whole or in part, from a few days to several
weeks in advance of the proper time. Often the peaches
on one or two limbs only will be diseased, all the rest
ripening in a normal manner. In such cases the prema-
ture peaches are full-grown, ripe, and high colored,
when those on the rest of the tree are green and but half
grown. These peaches, no matter what their natural
color, are more or less red and jourple spotted on the
skin, and splashed and streaked within. Sometimes
the normally white or yellow flesh is very beautifully
mottled, or almost entirely crimson ; again there is
hardly a trace of the abnormal color. The flavor of
immature peaches varies considerably, but they are usu-
ally insipid, and sometimes bitter.

*'The next symptom, which generally appears the
same season, but is sometimes delayed until the next, is
the appearance of diseased, dwarfed growths upon the
trunk and limbs. These growths bear diminutive leaves,
which are pale green, yellowish, reddish or white. They
often show a marked tendency to repeated branching,
sometimes as many as four sets of branches being devel-
oped within a few months. These growths may arise
either from obscure buds on the trunk and main limbs,
or from the ordinary winter buds. They may appear at
any time during the season, from spring until late au-
tumn. Often the winter buds push in October or No-
vember, after the foliage has fallen, or even in August
and September, wdiile it is still green and vigorous.

^' When attacked the tree is very often in a vigorous,
healthy looking condition, and sometimes during the

THE PEACH YELLOWS

71

whole of the first season there is no sign of disease be-
yond the appearance of a few premature peaches, the
fohage being fully grown and dark green, and the shoots
in no way dwarfed or sickly. As already intimated, the

FIG. 37. YELLOWS TUFT.

disease usually appears first in one limb or one side of
the tree, but sometimes in all j^arts of the tree at once,
or on opposite sides. No matter to how slight an extent
the tree is first diseased, it never recovers, but becomes

72 PUNGI AKB FUKGICJDES

entirely diseased in the course of two seasons, or at
most; three.

"The limbs first attacked are badly diseased, the
second year, their entire growth, shoots and foliage,
being much dwarfed and. of a sickly green, tinged with
yellow or reddish-brown. In course of two or three sea-
sons the entire growth of the tree assumes this appear-
ance, and is then a sufficient warrant for the common
name, such trees especially, when massed in orchards,
being distinguishable at some distance b}^ their yellow
or reddish-brown appearance, w^hich is in marked con-
trast with the beautiful dark green of healthy foliage.

" Trees not infrequently die outright the second,
year of attack, but ordinarily they languish for a num-
ber of years, dying gradually from the extremities down-
ward. Often such trees are barren after the first year,
or they may bear another crop of premature peaches,
which are, however, of small size and very inferior
flavor."

An orchard ruined by yellows is represented in
Plate A^II, while in Fig. 37 is shown a tuft of diseased
twigs.

Treatment. — ^N^o remedy for this disease is known.
The only successful treatment yet found is that of
promptly digging out and burning all affected trees.
In several States this is made compulsory by special
laws, and in Michigan, at least, it has proven quite a
satisfactory method of stamping out the disease.

Literature. — A very elaborate report upon the
peach yellows, jorepared by Dr. Erwin F. Smith, was
published in 1888, as Bulletin No. 9 of the Botanical
Division of the United States Department of Agricul-
ture. A short summary of the same results was also
published in the Department Eeport for the same year
(pp. 393-398). Since then Dr. Smith has published
various reports of progress in the j^ublications of the

THK PEA.CH ROT 73

Department and elsewhere, especially in Bulletin 1 of
the Division of Vegetable Pathology.

The Peach Rosette

The name Peach Rosette has been given to an ob-
scure disease affecting trees in various States, character-
ized by the presence of rosettes of leaves upon the
branches. It has been studied by Dr. Smith in connec-
tion with peach yellows, and is treated of in the publi-
cations referred to above, especially in the Journal of
Mycology (v. \1, No. 4).

The Peach Rot

Monilia fructigena

The main points in the development of this fungus
have already been discussed under the plum (pp. 56-58).
It also attacks peaches, and probably causes more loss
on this fruit than on the other. Dr. E. F. Smith, who
has made a special study of peach enemies, says : " This
fungus is more common and far more destructive than
any other observed on the peach in this country. It is
rarely absent from the orchard, and in rainy weather it
frequently destroys from one-half to three-fourths of the
crop, in some cases the entire crop. Under its influence
the fruit quickly loses its normal color and flavor, and
becomes an entire loss to the grower. As the fungus
invades the healthy tissues of the fruit the latter become
leather-colored, or dark brown, and the peach is said to
rot, although, as Von Thiimen first pointed out, the
change is not strictly a ^rot.'"

During unusually wet springs the blossoms of peach
trees are frequently destroyed by this fungus, and the
young twigs are also attacked. The spores are propa-
gated in vast numbers by the mummied peaches hanging
on the trees, and are blown through the orchard, carry-

PLATE VIII. PEACH BLOSSOMS BLIGHTED BY ROT FUNGUS.

THE PEACH EOT 75

ing destruction wherever they light ou a blossom. This
injury is sometimes called ^^ peach blight." Some blos-
soms so injured are represented at the right in Plate VIII,
from a drawing published by Professor F. D. Chester.
Some tufts of spores on a twig are shown at the left of
the same figure.

Treatment. — The remarks upon this subject con-
cerning the plum (p. 58) are equally applicable to the
peach. ExiDcriments made in Delaware indicate that a
considerable j^roportion of the rot may be prevented by
proper treatment. Professor Chester recommends the
following j^rocedure : Pick off late in autumn or early
in winter all mummied fruit on the trees. It would be
better to remove it at the time of picking, or soon after.
Spray with simple solution copper sulphate (one pound
to twenty-five gallons water) early in spring before fruit
buds begin to swell. Spray again with ammoniacal so-
lution copper carbonate as soon as these buds begin to
swell, and repeat the application just before the buds
open, to prevent injury to blossoms. ^'As soon as the
fruit shall have reached full size and begins to show
signs of color, make a third apj^lication. This should
be followed by two or three other applications at close
intervals of five or seven days during the ripening period.
A heavy rain followed by warm weatlier may, at this
vital period, cause the peaches to rot ra]ndly ; hence,
due regard should be given this point in regulating the
exact time when a spraying should be made. Due atten-
tion to this principle may save hundreds of baskets of
fruit, and the grower can well afford to make spraying
at the right time his first business." It may be doubted,
however, whether these late applications, are advisable,
from a sanitary standpoint. Treatment with copper
mixtures at frequent intervals during the ripening
period means the presence of copper salt upon the mar-
keted fruit, unless it is washed off after picking.

76

FUNGI AXD FUXGICIDES

Literature. — Dr. Smith's articles concerning the
injuries of peaches caused by this fungus may be found
in the Journal of Mycology, v. V, pp. 123-134, and sub-
sequent issues. An account of Professor Chester's ex-
periments is giyen in Bulletin XIX of the Delaware
College Experiment Station.

A

Fungi Affecting small Fruits

<

?;

FUNGI AFFECTING THE GRAPE

The Black Rot

Lcestadia bidivellii

This is the most generally destructive fungous dis-
ease of the grape in the United States. It is most inju-
rious in southern latitudes, being much less yirulent as
far north as Northern Ohio or Western New York than
in Tennessee or the Carolinas. Like most fungous dis-
eases, it develops with greatest rapidity during damp,
hot weather, or when nights with heavy dews alternate
with hot days.

The black rot fungus usually first appears on the
leaves early in summer in the shape of small, sharply
defined reddish-brown spots, having yellowish centers,
and dark brown or blackish borders, with numerous
minute black pustules scattered over the surface. A
short time afterward — generally about a fortnight — the
attack upon the fruit becomes noticeable.

According to Professor F. D. Chester, who has
studied tins disease in Delaware, ^'^the first appearance
of rot upon the berry shows itself as a light brown spot,
caused by the decay of the underlying pulp, this spot
increasing in size so as to involve the entire berry.
Simultaneous with this change, the parts first affected
turn black and become covered with minute black pus-
tules. Finally the entire berry dries and shrivels, the
skin crumpling into angular folds. The entire berry is,
at this stage, profusely and uniformly covered with the
pustules. If a thin section be made through a rotting
berry, the microscope will reveal the presence of minute

79

80 FrJy"GI Ais'D PUJS'GICIDES

threads growing into and between the cells. These
threads which form the vegetating portion of the fun-
gus, technically mycelium, are in diameter only about
one-sixth that of a single fiber of cotton wool. It is the
growth of these threads through the tissues of the berry
which causes the decay and shrivelinof, externally mani-
fest as black rot.

Microscopic Characters. — At points beneath
the cuticle the mycelium collects into little knots, which
afterwards develop into the black jnistules seen u2:)on

the surface. These pus-
tules are globular tliick-
w^alled sacs or concepta-
cles, technically pycnidia,
which at maturity are filled
with elliptical spores,

FIG. 38. BIT OF SKIN SHOWING PUS- ^Hown as stylospores. The

TULEs, AviTH EscAPixG COILED stylosporcs comuiouly es-

MAssEs OF SPORES. iiAGxiFiED. ^.^^^ through au apcrturc

or pore in the summit of the jiycnidium in the form of
threads ; these threads are masses of spores glued to-
gether by some adherent substance. Fig. 38 represents
a small bit of the cuticle or skin of the grape, with the
pustules considerably magnified; through the pore in
the summit of four of them the coiled masses of spores
are escaping."

These stylospores are scattered through the vine-
yard, and those which lodge upon green grapes with a
droj) of moisture present, germinate by sending out a
little tube, which penetrates the skin and starts the dis-
ease anew.

Besides these stylospores, there are three other
kinds of spores produced by the black rot fungus. They
are called by botanists the spermatia, the conidia, and
the ascospores. The latter are produced in May and
June, by the mycelium in the berries destroyed the pre-

THE BLACK ROT

81

vious year, and so are supposed to start the disease for
the season. Full accounts of the development of these
various spores will be found in the articles referred to
below, under the head of Literature.

Treatment. — Spray with the ammoniacal solution
of copper carbonate or the Bordeaux mixture five to
eight times, making the first application when the buds
begin to swell, early in May in the Northern States, and
repeating at intervals of fifteen days. In case Bordeaux

FIG. 39. OUTFIT Foil SPRAYING GRAPES.

mixture is used, substitute the ammoniacal solution for
the last one or two sprayings, to avoid spotting the fruit.
The time of the first apj^dication will, of course, vary
with the latitude, — earlier in the South than at the
North. A convenient spraying outfit for vineyard use
is illustrated in Fig. 39. It consists of a barrel witli
pump attached, mounted crosswise in a wagon. One
man drives and pumps, and another sprays the vines
behind the wagon. The hose terminates in an S-shaped

82 PUNGI AKD FUNGICIDES

pipe, by means of 'which the operator can spray any part
of the vines. The great increase in value of sprayed
over iinsprayed grapes has been repeatedly demonstrated.
It has been found that spraying with Bordeaux mixture
not only prevents the disease, but keeps the vines in a
much healthier and more thrifty condition than un-
sprayed vines not diseased.

Literature. — The black rot fungus has been very
frequently discussed in recent horticultural literature,
especially by Messrs. Scribner, Galloway, Chester and
others. The principal articles are to be found as fol-
lows : United States Department of Agriculture, Ee-
ports, 1880, pp. 109-112; 1887, pp. 326-327; 1888, pp.
326-334; 1889, pp, 399-105 ; 1890, pp. 394-396, and in
various bulletins; Delaware Experiment Station, Bul-
letins 'Nos. VI and X ; Proceedings Society Promotion
of Agricultural Science, 1888, pp. 68-73; 1889, pp.
62-64 ; 1890, pp. 58-63.

The Downy Mildew

Peronospora viticola

In the Xorthern States the downy mildew, or
brown rot, is one of the most destructive fungus ene-
mies of the grape. It is distributed over nearly the
entire eastern half of the United States, and occurs both
upon the wild and cultivated varieties of grapes. It
probably lived upon the former before the introduction
of the latter. It appears usually about the time the
vines blossom, producing upon the leaves a distinct
whitish mildew which has earned for it its common
name. The leaves, and often the young shoots, are
more or less injured, and from them the fungus spreads
to the newly formed berries, coating them also with mil-
dew and causing them to fall off. The damage contin-
ues throughout the summer. When larger grape berries

THE DOWNY MILDEW 83

are attacked their growth is checked, and they gradually
turn gra}?ish or brown.

A good example of the parasitic fungi affecting
higher plants is furnished by this downy mildew of the
gi'ape. It is a minute, parasitic plant that develops
at the expense of the tissues of the grape, thus causing
blighting of the leaf and decay of the fruit. It attacks
all the green parts of the yine, including the young
shoots, as well as the leaves and berries, and, like other
fungi, reproduces by means of spores.

When one of these spores falls upon a leaf where
there is sufficient condensed moisture, its contents divide
into a number of distinct
particles, which escape
through [in opening in the
spore- wall. Each of these
particles moves about in
the drop of water on the
leaf for a few minutes,

then comes to a standstill fig. 40. section of leaf showing
and germinates by sending mycelium of fungus, magnified.

out a little tube — somewhat as a kernel of corn in moist
soil sends out its germinating radicle — and this tube
penetrates the epidermis, or skin of the leaf. Once
inside, the tube continues to grow, pushing about be-
tween the cells of the leaf, and forming the mycelium,
or vegetative portion of the fungus, which may be
likened to the roots of the higher plants. As there is
little nourishment to be obtained between the cells, this
mycelium develops minute processes, which push through
the cell walls and absorb the cell contents. A small sec-
tion of an affected leaf, greatly magnified, is represented
in Fig. 40, the unshaded double-walled spaces represent-
ing the leaf cells, the shaded part between the walls the
mycelium of the fungus, and the projections marked
a, a, the processes, or suckers, that penetrate the cells.

84

FUXGI Ais^D FUKGICIDES

After this mycelium has developed in the leaf for
some time, it is ready to j^roduce its spores. Conse-
quently it sends out through the breathing pores, or
stomata of the leaf, its fruiting branches. These bear

upon their tips small oval
bodies, which are tlie spores.
Some of these fruiting
branches are shown in Fig. 41.
The '^mildew" visible to the
naked eye is composed of these
fruiting branches and their
spores. It only develops under
certain atmospheric condi-
tions ; so that the mycelium
may exist in the aSected parts
of the vine for some time be-
fore this outward manifesta-
tion of its presence occurs.
Besides the spores above de-
scribed, which are jiroduced
during the summer season,
and, consequently, are called
summer spores, there is devel-
oped in autumn a different
class of spores, by which the fungus passes through the
winter. Hence, these latter are called the winter spores.
Treatment. — Eau Celeste is a practical and effi-
cient preventive of this disease. Spray first a week or
ten days before the vines blossom ; second, as soon as
the berries are well set ; and third, about three weeks
later. In very wet seasons it may be desirable to spray
a fourth time, but this is seldom done. The other cop-
per fungicides, especially the Bordeaux mixture, would
doubtless prove equally effective, but eau celeste has
been most generally used against this fungus, at least in
some of the more important grape-growing regions of
the country.

FIG. 41. FRUITING BRANCHES,
GREATLY MAGNIFIED.

THE POWDERY MILDEW 85

Literature. — An excellent account of this downy
mildew, by Professor F. L. Scribner, may be found in
the United States Department of Agriculture, Keport
for 1886 (pp. 96-105). Since then much has been pub-
lished, in the Department reports and bulletins, in ex-
periment station bulletins, and in the horticultural
press, concerning remedial measures.

The Powdery Mildew

Uncinula ampelopsidis

The powdery mildew of the grape seldom becomes
seriously destructive, except in the Southern States and
along the Pacific coast. It only thrives in very dry
weather, and attacks all the green parts of the vine.

This fungus is closely related to the powdery mil-
dews affecting apple and gooseberry, which are discussed
on other pages of this book. During summer reproduc-
tion takes place by means of summer spores, which ger-
minate upon the moist surface of leaf or fruit, the ger-
minating tubes sending out suckers (Fig. 42 c) which
penetrate the tissues of the host, and enable the myce-
lium to develop on the outside of the cuticle or skin.
In this way the mycelium may grow all over the outer
surface of the leaf, giving it a cobwebby appearance,
and drawing nourishment from it by means of the suck-
ers already mentioned. After it has grown for awhile
in this way it sends up certain vertical branches (b),
which soon develop transverse partitions, and thus pro-
duce the small oval summer spores. These are light
and easily distributed by the wind, and serve for the
rapid extension and propagation of the fungus during
summer.

Later in the season the mycelium produces another
kind of spores — the so-called winter spores. These are
more complicated in structure than their summer repre-
sentatives ; as seen under the microscope, they consist

86

PUKGI AXD FUi^GICIDES

externally of a small spherical case, from which project
fifteen or twenty, or sometimes more, rather long deli-
cate ajipendages with recurved tij^s, as seen in a, Fig. 42.
This is the outer spore-case (which hotanists call the
2JerUliecium). If it be crushed it will break open on
one side, and there will be pushed out about half a
dozen small, OTal, flattened bodies — the inner spore
cases, or asci — within which may be seen from four to

FIG. 42. POWDEKY MILDEW. 5L\GXIFIED.
CT, Peritliecium; 6, mycelium ; c, germinating spore.

six small bodies, which are the winter spores. By
means of these the fungus passes through the winter.

Microscopic Characters. — A good idea of the
structure of this powdery mildew may be obtained from
Fig. 42. A small piece of the mycelium running over
the surface of the leaf is represented in l ; on the lower
side are tAvo of the i^eculiar suckers which penetrate the
tissues of the host-i^lant to draw out nourishment for
the fungus, and on the upper side are represented the
vertical branches from which the summer spores are pro-
duced, as well as one loose spore. In c one of these

iHE GKAPE a:n^thracnose 87

spores is shown in process of germination, one of the
germ tnbes having already formed a sucker on its side.
The winter spore case, with the inner cases escaping
through its ruptured side, is well shown in a.

Treatment. — This disease may easily be prevented.
According to Mr. Galloway, "it succumbs readily to
sulphur, either in the form of flowers of sulphur, or
solutions of the sulphide. In applying the sulphur, bel-
low^s should be used, and the first applications should
be made ten or twelve days before the flowers open, the
second when in full bloom, and a third three weeks or a
month later if the disease seems to be on the increase.
The best results are obtained with the thermometer
ranging from 80° to 100° F. In this temperature fumes
are given off which quickly destroy the fungus. We
have obtained excellent results in treating this disease
with a solution made by dissolving half an ounce of
potassium sulphide to the gallon of water. This prepa-
ration is cheap, and can be quickly and effectually ap-
plied with any of the well-known spraying pumps. The
greatest care should be exercised in making the second
spraying, which, by the way, should be at the same
time as that mentioned for the flowers of sulphur, in
order to protect the blossoms from the fungus."

Literature. — An excellent account of this fungus,
from the pen of Professor Scribner, may be found in the
Report of the United States Department of Agriculture
for 1886 (pp. 105-109). There are many shorter arti-
cles concerning it scattered through our horticultural
literature.

The Grape Anthracnose

Sphaceloma ampelinum

The peculiar and characteristic injury produced
by the fungus of anthracnose easily distinguishes it
from the other diseases of the vine. It attacks all the

88

FUIfGI AXD FUNGICIDES

green parts of the plant, nsnally doing most damage to
the young shoots and the fruit. On the former it ap-
pears at first in the shape of
small round brown spots,
depressed in the center, and
having a slightly elevated
dark colored border. As the
shoots grow the spots grad-
ually elono-ate, and their
middle portions become
more distinctly depressed be-

cause of the killing of the

tissue. The effect upon the
fruit is w^ell illustrated in
Fig. 43 ; there first appears
a small grayish spot, having
its margins dark brown.
The spot gradually enlarges,
and there is frequently de-
Telojoed just inside the dark
brown margin a bright ver-
milion ring. On account of
this, the disease is often
called the '' Bird's-eye" Rot.
As the fungus progresses the
growth of the berry is
checked, and it finallv be-
comes a dry, withered mass
of skin, surrounding the par-
tially developed seeds. The
manner of development upon
the leaves is similar to that

FIG. 43. ELVIRA GRAPE AFFECTED UpOU thC grCCU shoOtS. LlkC

BY AXTHRAcxosE. ^^j^g^, fungi, thc authrac-

nose fungus reproduces by means of minute spores, some
of which are represented, highly magnified, at Fig. 44 c.

THE GEAPE ANTHRACKOSE

89

When one of these spores falls upon a green leaf, stem or
fruit where there is a particle of water, it sends out a
germinating tube, which penetrates the skin or cuticle.
On the inside it begins the production of mycelium
which grows near the surface, and finally produces, in
certain spots, quantities of spores. These masses of
spores gradually push the skin outward, as shown in a,
and finally rupture it and escape, as seen in h. They
are then blown and washed about, and such of them as
alight on the green parts of other vines when conditions
are favorable for germination, start the fungus again.

.%

IP

6

&

FIG. 44. ANTHRACNOSE.
a, fc, Vertical section of grape showing development of spores; c, spores. Magnified.

The light colored and white varieties of grapes are
the ones most affected by anthracnose. A bunch of
Elviras injured by this disease is represented in Fig. 43.

Treatment. — This is a difficult disease to prevent.
The treatment usually recommended is to cut out all
injured canes during winter, and early in spring, before
the buds start, to spray the vines thoroughly with a
strong copperas (iron sulphate) solution. Mr. E. P.
Powell has reported successful results from a solution of
ten pounds of copperas to a barrel of water. In case
the disease appears, a powder composed of equal parts

90

FUNGI AXD rUITGIClDES

of sulphur and lime may be dusted on ; or the Bordeaux
mixture may be applied.

Literature. — Professor F. L. Scribner has joub-
lished, in the Report of the United States Department
of Agriculture for 1886 (pp. 113-115), an extended
account of grape anthracnose. Since then it has been
frequently treated of in The Journal of Mycology, and
in experiment station bulletins and reports.

FUNGI AFFECTING THE CURRANT AND

GOOSEBERRY

The Leaf=spot Disease

Septoria ribis and Cercospora angulata

The foliage of currants and gooseberries is often
attacked early in summer by two or more species of
fungi, which produce small brownish spots, at first often
no larger than a pin head, but gradually increasing in

size until a consid-
erable proportion of
the leaf surface is
affected. Some-
times several spots
may run together,
forming a large
blotch ; and these
blotches, as well as
the older spots, are
often of a dead gray
color. When the
leaves are badly
attacked they fall
prematurely, so that
the bushes may be-
00 me as bare in
FIG. 45. SPOT DISEASE OF cTTRRANTs. August as thcy Or-
dinarily are in December. Of course, the effect upon
th.e plants of such a loss of foliage is disastrous. If a
heavy crop is already hanging the plant may be unable

91

92 rUl^GI AND FUXGICIDES

to ripen it ; and, in any case, it has no opportunity to
store up yitality for the coming season's fruitage.

The life-histories of the two S2:)ecies of fungi con-
cerned in the attack do not seem to have yet been defi-
nitely worked out. Sometimes the Cercospora is the
cause of the disease, and sometimes the Septoria. The
spores apparently pass the winter in connection with the
fallen leaves.

Treatment. — Spraying with some fungicide, like
the ammoniacal copper carbonate solution, promises to
be a preventive of this disease. The first application
should be made^arly — soon after the leaves fully expand.
Gathering and burning, or composting the fallen leaves,
will prove helpful in destroying the spores. In case the
leaves are com2')osted, the resulting fertilizer should, of
course, be applied to some crop away from any currant
or gooseberry bushes.

Literature. — This spot disease has been discussed
by Professor A. B. Seymour, in the report of the Min-
nesota State Horticultural Society for 1886 (v. XIV, p.
239); by Professor L. 11. Pammel, in Bulletin Xo. 13
of the Iowa Experiment Station (pp. G7-70) ; and by
Dr. B. D. Halsted, in the report of the Xew Jersey
State Horticultural Society for 1889 (p. 156).

The Currant Anthracnose

Glceosporium ribis

This disease has only attracted attention in this
country during recent years, and has been especially
studied in Xew York by Professor Dudley (Cornell Ex-
periment Station, Bulletin XV). It first aj^pears in
June or the early part of July, in the shape of small,
dark brown or blackish spots, about one-twenty-fifth of
an inch in diameter, chiefly on the upper leaf surface.
The spots enlarge, and the cuticle of the leaf is pushed

THE GOOSEBEKRY MILDEW 93

upward by the developing spores, which escape through
a small opening, in a peculiar, tendril-like mass, the
individual spores being held bogether by a mucilaginous
substance. The raising of tlie cuticle gives the spots a
white or grayish tint. The infested leaves become dull
brown or yellow in color, and drop off, commencing
sometimes by midsummer, and defoliating the bushes in
August. Of course, the fruit on bushes so defoliated
does not mature properly. Spraying with fungicides,
such as the ammoniacal solution of cojiper carbonate, is
recommended to prevent this disease.

The Gooseberry Mildew

Sphoerotheca mors-uvce

For many years it has been impracticable to grow
the finer foreign varieties of gooseberries in the United
States, on account of their liability to injury by the
gooseberry mildew. This fungus usually appears in
spring upon the partially developed leaves and buds,
first showing as a sparse, cobwebby covering, which,
later, is made to appear white and powdery by the pro-
duction of the summer spores. The young berries are
also attacked, generally being dwarfed and one-sided as
they develop. As the summer progresses the infested
leaves become brown and dead, and are generally cov-
ered with a thick growth of the fungus mycelium.

With most of parasitic fungi treated of in these
pages the mycelium, or vegetative portion of the fungus
is internal; that is, it develops inside the outer cuticle
of the host-plant, among the cells of leaf, stem or fruit,
sending out its fruiting branches when it has completed
its growth. But with the class of so-called ''powdery
mildews," to which the present species belongs, the my-
celium is external, developing on the outside of the
host-plant. The mycelium consists of slender white

94

FUNGI AND FUNGICIDES

threads which run oyer the surface of the leaf, and
obtain nourishment bj sending down into the cells short
branches, often called suckers. During the summer
these threads also send upward in the air certain other
branches, which gradually divide into a number of
parts, as shown in a, Fig. 46, and thus produce the
summer spores, or conidia. These summer spores are
very light, and are blown about by the wind ; when one
falls upon a damp gooseberry leaf it germinates by send-
ing out a slender tube, from which the mildew starts
anew. As the summer spores are unable to survive the
winter, the fui^gus produces, especially late in the sea-

no. 46. SPORES OF GOOSEBEERY MILDEW. MAGNIFIED.

son, another kind of spures, the so-called winter spores.
These are much more complicated in structure than the
others. As seen under the microscope, they consist
externally of a small round case, from wiiich project
about a dozen short delicate appendages, like those rep-
resented in h, Fig. 46. This is the outer spore case
(called by botanists the perWiecium). If it be crushed
it will break open on one side, and there will be pushed
out a flattened oval body — the inner spore case, or ascus
— within which may be seen eight small bodies, which
are the spores [h). By means of these the fungus sur-
yiyes the winter.

THE GOOSEBERRY MILDEW 95

Treatment. — Spray with a solution of potassium
sulpliide (liver of sulphur) at the rate of one-half ounce
to one gallon of water. Begin as soon as the leaves
commence unfolding, and repeat the application at inter-
vals of eighteen to twenty days. The sulphide dissolves
more readily in hot than in cold water. This treatment
has proven entirely efficacious for a number of years at
the Isew York Experiment Station. Early in the sea-
son the Bordeaux mixture may be used instead of the
sulphide if moi-e convenient.

Literature. — An excellent article concerning this
disease, by Dr. B. D. Halsted, may be found in the
Eeport of the United States Department of Agriculture
for 1887 (pp. 373-380). It has also been discussed in
the reports and bulletins of the New York Experiment
Station, and in various books and papers on horticul-
tural topics.

PLATE X. KASPBERRY AFFECTED BY AXTHRACNOSE.

FUNGI AFFECTING THE RASPBERRY
AND BLACKBERRY

The Raspberry Anthracnose

Gloeosporium venetum

Although this fungus is a widespread enemy of
raspberries and blackberries, public attention was first
called to it only about twelve years ago, when Professor
T. J. Burrill published an account of it, under the name
Easpberry Cane Rust, in the Agrimdtural Review.
Fruit growers frequently call the disease ^^sun scald,"
but its more proper name is anthracnose.

This fungus especially infests blackcap raspberries
and the thornless varieties of blackberries. It appears
both upon the canes and leaves. On the former it may
generally be found late in spring or early in summer on
the young shoots, when about a foot high, in the shape
of small reddish-purple spots, scattered irregularly over
the surface near the ground. As the canes grow these
spots increase rapidly in size, their centers becoming
grayish-white, and other spots appearing on the upper
portions. There is an elevated dark purple margin
around each spot, representing the division between
healthy and diseased tissues. As the season advances
the spots continually enlarge, many of them finally run-
ning together to form irregular longitudinal blotches,
which sometimes run clear around the cane and thus
girdle it. The injury extends through the outer bark,
frequently rupturing it, and sapwood (cambium layer),
but usually does not penetrate the pith. As the tissue
7 97

98 rUXGI AXD FUNGICIDES

is killed the purple color of the margin changes to
brown. The purple sjDots also appear on the stems of
the lower leaves, gradually extending outward, until the
whole leaf stem may be affected. Minute purplish dots
are also to be found upon the leaves themselves, indicating
that the fungus is developing there. In the center of
many of the spots one may often see little raised patches
consisting of the sjoores.

Of the effect of raspberry anthracnose, Miss Freda
Detmers says: '^^The disease is not fatal the first sea-
son, nor does it seem visibly to effect the growth of the
young canes ; but the next season, when last year's
young canes bear fruit, its destructiveness becomes but
too apparent (Plate I, Frontispiece). The effects of the
fungus are most noticeable at the time of the ripening
of the berries, which do not attain to a normal size, but
shrivel, and finally dry up ; the leaves are much smaller
than healthy ones, and have a generally unhealthy ap-
pearance, later turning yellow, then brown. The canes
finally become blackened and die."

The mycelium, or vegetative portion, of the rasp-
berry anthracnose consists of slender, microscopic threads
which penetrate between the cells of the plant, and
absorb their nourishment ; the cells thus robbed become
first discolored, and then they shrivel and dry up, the
tissues finally becoming dead. Toward the center of
this dying tissue the mycelium threads unite to form a
mass of slender club-shaped bodies {lasidia), which
push outward on the thin bark cuticle, or skin, until
the latter is ruptured. On the end of each of these
club-shaped bodies there is produced a single spore
(conidiiim). Both the club-shaped bodies and the spores
are at first enveloped in a yellowish, gelatinous covering,
which, however, is soluble in water, so that during the
first rainfall it dissolves and the spores escape. The
shajoe of the spores is represented in Plate XI ; they

PLATE XI. AM'UKAOJSOSIS OF KASPBEKRY.

100 FUKGI AND FUi^GICIDES

are carried to new places on the plant during rains, and
there they germinate and start the disease anew. Many
of them are probably blown from i^lant to plant and
field to field by the wind, and thus the disease is spread.
All of these spores are the so-called summer spores
(conidia) ; no true winter spores have yet been found.
It is supposed that the mycelium is i^erennial, carrying
the fungus through the winter.

Treatment. — Raspberry foliage is yery sensitive to
the corrosive action of fungicides, so that care in treat-
ment is necessary. The most successful results in pre-
venting this disease, as yet obtained, are those reported
by Mr. W. J. Green, of the Ohio Experiment Station,
who used a dilute Bordeaux mixture. His directions
are as follows : ^^The first application should be made
early in the spring before the leaves open, at which time
the spraying should be very thoroughly done. The sec-
ond application should be made soon after the young
canes appear above ground, and the spray directed to
them alone. The third application is to be made about
two weeks from the date of the second, taking the same
precaution to spray the young canes only. The fourth
and last application should be made just previous to the
time of blooming, in the same manner as advised for the
second and third sprayings. Raspberry leaves are very
tender and the mixture injures them slightly, but not
enough to preclude its use, especially if some care is
taken to keep it off the leaves of the bearing canes. The
leaves on the young shoots of the current season's growth
are not so easily harmed, hence no pains need be taken
to keep it off them."

Mr. Green also reports good results from the ammo-
niacal cojoper carbonate solution, ^^with even less harm
to the foliage, but, all things considered, the dilute
Bordeaux mixture is preferred." It is advisable to cut
out and burn all fruiting canes each summer as soon as
the crop is gathered.

ORAKGE RUST OF BLACKBERRIES

101

The most extended account of this disease is pub-
lished in the 1887 Report of the Department of Agri-
culture (pp. 357-3G1).

The Orange Rust

Cceoma nitens

The orange rust, or red rust, of blackberries, is fa-
miliar to most growers of small fruits. The disease
becomes noticeable as soon as the foliage expands in

FIG. 47. ORANGE RUST.

a, Under surface of Ijlackberry leaf showiuLf si)ots of pecidium sta^e; 6, same of
raspberry leaf showing both secidium and Puccinia spots.

spring, aifected leaves having a peculiar golden color,
which at once distinguishes them. A little later the
surface becomes more or less covered with small round
patches of orange-colored spores, to which the common
name is due. The life-history of the fungus has only
recently been definitely worked out.

The fungus exists on the blackberry plant in two
very different stages. The orange spores that are devel-
oped in spring and early summer, as shown in Fig. 48,
belong to the CBcidium stage. They germinate on the

102

FUNGI AND rUNGICIDES

leaves of raspberry and blackberry ; the germinating
tubes enter the stomata, or breathing pores, of the leaf,
develop a mycelium inside, and finally produce on the
surface the sj^ores of the teleuto stage, which has here-
tofore been considered an entirely different fungus,
called by botanists Puccinia loechiana. These Puccinia
spores are believed to be washed on to the underground

FIG. 48.

SECTIOX OF BLACKBERRY LEAF, SHOWLVG DEVELOPMENT OP
ORANGE RUST SPORES. 3IAGNIFIED.

shoots, and to infect them with the mvcelium, which
subsequently produces the orange spores of spring.

Blackberries are most commonly affected by this
fungus — especially certain varieties — but blackcap rasp-
berries often suffer also.

Treatment. — All diseased canes should be cut out
and burned as soon as they show signs of disease, leaving
none to develop spores to infect other j^lants. In con-
sidering varieties, select — other things being equal — those
least liable to the disease. Insist on your neighbors
keeping the rust in check, and also look out for wild
plants that have it. A spraying with fungicides will

ORAI^GE RUST OF BLACKBERRIES

103

doubtless assist in preventing infection, especially of the

Puccinia stage.

An extended account of this disease, by Mr. G. P.
Clinton, occurs in Bulletin 29 of the Illinois Experi-
ment Station.

FUNGI AFFECTING THE STRAWBERRY

The Strawberry Leaf=blight

Splicerella fragarice

The strawberry leaf -blight, leaf-rust, or leaf-spot
is the most destructive of the numerous fuDs^ous ene-
mies of this delicious fruit. The disease apparently
occurs in the United States wherever strawberries are
grown, having been recorded from Maine in the north
and east, to Florida in the south, and California in the
west. Over a large portion of this vast territory it fre-
quently becomes very seriously injurious.

This fungus first appears on the upper surface of
the leaf in the shape of small purplish or reddish spots,
which, though minute at the start, increase rapidly in
size. Their centers also gradually become lighter in
color, changing from purple, or reddish, to brown, then
to gray or white, but the margin generally remains pur-
ple. The size of the spots varies greatly, single ones
sometimes being a quarter of an inch in diameter, and
others running together to form large discolored blotches.
Badly affected leaves finally wither, turn brown and die.
The vitality of affected plants is seriously impaired, and
if they are not killed outright, the cro]) of fruit pro-
duced by them is diminished.

Professor H. Garman says that if one of the dis-
eased spots '^'hQ cut through with a pair of fine scissors,
the leaf will be found, at the point where the spot is
formed, much thinner than elsewhere, because of the
killing and drying out of its substance. Examined
under a microscope the fungus may now be found to

104

THE STRAWBERRY LEAF-BLIGHT

105

have pushed through the tissues of the leaf, and to have
formed all over the brown central region of the spot,
but most abundantly at its margins, small whitish tufts,
looking like microscopic shrubs. These are the fruiting
parts of the parasite, and are made up of numerous

FIG. 49. STRAWBERRY LEAF AFFECTED WITH BLIGHT.

threads, each bearing at its summit a long jointed spore.
As these latter ripen they are set free, and are scattered
upon fresh leaves by winds and rains, to germinate
there, push into the leaves and form new spots." The
fungus is propagated by these long spores throughout

106

PUJsGI AXD FUNGICIDES

the summer, but in autumn the threads of mycelium
"form solid tissue-like masses in the dead parts of the
spots," which finally appear at the surface as small black
dots. By means of these dots or nodules, (which are
called by botanists sclilerotia) the fungus mainly passes
the winter, but Professor W. R. Dudley has shown that

/

FIG. 50. LEAF-BLIGHT FUNGUS. MAGNIFIED.

it is also carried through the winter by the mycelium in
the leaves, and the so-called winter spores, or ascospores.
Microscopic Characters. — The process of devel-
opment of the summer spores, or conidia, is represented
in h, Fig. 50, which shows a tuft of them after having
broken through the upper epidermis of the leaf. At c
may be seen some of the individual conidia, three of

THE STRAWBERRY LEAF-BLIGHT 107

which have sent out germinating tubes. The winter
spores within their cases, as they are borne on the leaf
in partially closed sacs — called perithecia — are seen in e,
and at /some of these cases containing spores are repre-
sented more highly magnified.

Treatment. — It has been repeatedly shown that
this leaf -blight may be prevented by the Bordeaux mix-
ture. Usually spraying after the crop is gathered, espe-
cially when the plantation is mowed and burned over,
keeps the disease sufficiently in check, but additional
spring sprayings — one when the new leaves start, and
another just before the blossoms open — will prove of
much benefit. Young, non-bearing plantations should
be sprayed two or three times during summer.

Literature. — The strawberry leaf-blight has fre-
quently been discussed in the American literature of
plant diseases. In 1885 Professor Wm. Trelease pub-
lished an article concerning it in the report of the AYis-
consin Experiment Station for that year (pp. 47-58).
Professor F. L. Scribner has an elaborate account of it,
illustrated by a colored plate, in the report of the United
States Department of Agriculture for 1887 (pp. 334-341).
Other articles concerning it have been published by Pro-
fessor Arthur in the report of the New York Experi-
ment Station (1888, p. 351) ; by Professor Dudley, in
the Bulletin of the Cornell University Experiment Sta-
tion (XIV) ; and by Professor Garman in the Bulletin
of the Kentucky Experiment Station.

A

Fungi Affecting shade Trees,
Ornamental Plants and Flowers

PLATE XII. HOLLYHOCK LEAF AFFECTED WITH RUST.

FUNGI AFFECTING SHADE TREES

The Catalpa Leaf=spot Disease

Phyllosticta catalpce

Early in summer small discolored spots frequently
appear in the leaves of Catalpa trees. Although minute
at first they gradually enlarge, and two or more often
run together to form brown or blackish blotches, which
sometimes involve most of the leaf. In badly affected
trees the tissues of the leaves may be so diseased as to
cause defoliation during the latter part of summer. In
less severe cases the affected areas may drop out of the
leaves, round holes appearing in their stead.

This disease is caused by a fungus which originates
in spores like those represented in Fig. 51, J. When
one of these spores falls upon a moist catalpa leaf it ger-
minates by sending out tubes, as illustrated in c, of the
same figure, and these germ tubes enter the leaf-tissues,
where they develop a mass of mycelium, which grows at
the expense of the leaf cells, the latter becoming disor-
ganized and turning brown. After the mycelium has
developed in this way for some time it produces spores
in certain parts of the spot, rupturing the skin, or cuti-
cle, of the leaf, to enable the spores to escaj^e, as shown
in a. These spores are blown or washed upon other
leaves where, under favorable conditions, they may ger-
minate and start new spots. There is another fungus,
quite different in microscopic characters from the one
illustrated, usually found on the spots, but it is believed
to be a secondary form growing on the disorganized

111

112

FUis'Gi a:n'd fungicides

tissues, which the fungus under consideration first
produces.

Treatment. — The burning of fallen catalpa leaves
in autumn is an advisable preventive measure. Proba-
bly early sprayings with Bordeaux mixture, or some sim-
ilar fungicide, would prove an effectual remedy.

The only important article on this subject that has
come to the writer's notice may be found in the report

'^5::::^

FIG. 51. CATALI-A LEAF-SPOT,
a, Section showing spore production ; b, spores ; c, spores germinating. Magnified.

of the TJnited States Department of Agriculture for
188? (pp. 364-306).

The Cottonwood Leaf = rust

Melampsora populina

The leaves of poplars and cottonwoods are quite
commonly covered on the underside with an orange col-
ored powder, which consists of the spores of a rust fun-
gus. Such leaves usually fall prematurely, so that the
trees may be defoliated long before the proper time.
Later in the season the orange powder is replaced on the
leaf by reddish brown, waxy pustules. This is the win-
ter stage of the fungus. Eaking and burning fallen
leaves is advised, as a remedial measure. This fungus
is discussed in the 1888 Keport of the Department of
Agriculture (pp, 390-392). Eecent experiments have

THE MAPLE LEAF-SPOT DISEASE 113

sliown that this malady may be prevented by early spray-
ing with Bordeaux mixture.

The Sycamore Blight

Gloeosporium nervisequum

The tips of branches of sycamore trees often exliibit
a peculiar injury in spring, which is commonly attrib-
uted to frost. The leaves turn brown, presenting a
scorched appearance. The effect is really due to a para-
sitic fungus, which produces its fruit in minute black
pustules that may be found on the injured leaves. No
remedy, except that of cutting and burning affected
twigs — impracticable in most cases — has been suggested.
The disease is discussed in the report of the Department
of Agriculture for 1888 (pp. 387-389).

The Maple Leaf=spot Disease

Phyllosticta acericola

The leaves of various species of maple are often
attacked by this fungus, which appears late in spring or
early in summer in the shape of minute, blackish circu-
lar spots. As the mycelium inside the leaves develops
the spots increase in size, and their color often becomes
more brownish, the shade differing considerably with
the various kinds of maple. Many of them finally
become a half inch or more in diameter, and two or
more often run together to form a large blotch ; in case
of severe attacks so much of the leaf-surface may be
affected that the foliage withers and falls from the tree.

The disease could probably be checked by fungi-
cides, but the application of these to large numbers of
shade trees is usually impracticable. In nurseries, how-
ever, they may be employed. Gathering and burning
the fallen leaves helps to check it by destroying the
spores. An illustrated discussion of this fungus may be
found in the Department of Agriculture Report for 1888,
pp. 383-386. 8

FUNGI AFFECTING THE ROSE

The Rose Mildew

Spherotheca pannosa

The mildew of roses is probably familiar to every
one who has grown these plants in a greenhouse. The
characteristic covering of mildew upon the leaves is very
likely to appear if the roses are neglected in any way.
Professor S. T. Maynard says that ^'long experience in
growing the rose has led many to believe that the rose
mildew is brought on by various conditions that weaken
the vigor of the leaf, such as ^vant of an abundance of
plant food in a proper condition, unhealthy condition of
the soil, often resulting from improper drainage, irregu-
lar or over-watering, or too sudden changes of tempera-
ture, especially after the j)lants have been forced at a
high temperature. The successful rose grower, there-
fore, is one who, by constant care and good judgment,
always provides against any or all of the above causes."

Treatment. — The ordinary method of preventing
the mildew is to close the house and fill it with sulphur
fumes three times a week. The sulphur may be put in
a thin iron kettle over a small kerosene stove, placed
where there is no danger of upsetting, and only fire
enough should be turned on to boil the sulphur. If it
catches fire the plants in the house might be ruined.
Probably spraying with copper carbonate solution, or
a similar fungicide, would also prove an effectual
preventive.

114

THE KOSE RUST 115

The Rose Rust

Phragmidium mucronatum

This is a distinct and easily recognized affection of
roses which has long been known, both in Europe and
America, to lovers of the queen of flowers. It seldom
attacks tea roses, usually confining its attention to the
hardy hybrid perpetuals. It generally appears early in
summer in the form of orange-yellow spots upon the
leaves, their petioles, or the green growing stalks. At
first these spots are small, but they grow in size, espe-
cially on the leaf petioles and young shoots, where they
generally become elongate, while the petioles and shoots
often become twisted and otherwise deformed. About
midsummer the orange-yellow color gives way to a brick-
red color, the latter appearing on the same spots and
being due to the production of a different kind of spore.
Towards autumn still another kind of spore is produced,
developing in small blackish masses, mostly on the
under sides of the leaves. These masses consist of the
so-called winter spores, which live over winter among
the fallen leaves, and in spring start, the disease again.

Microscopic Characters. — This is one of those
fungi which produce different spores at different seasons.
The spring form, producing the orange-yellow s^jots on
the leaves, is composed of the so-called cecidio-spores.
They are small spherical or angular bodies, which serve
for the rapid spread of the disease as they are blown
about by the wind. The spores forming the brick-red
spots of midsummer are called the uredo-spoi^es. They
are borne on short pedicels, and though spherical in gen-
eral outline, have the outer surface roughened by numer-
ous projecting points. One of the spores composing the
black spots found late in the season — called by botanists
the tdeuto-spore — is represented at Fig. 52. It is very
different from either of the preceding forms, being cyl-

116

FUKGI AXD FUXGICIDES

.O

\j

\n

indrical, divided into numerous cells by transverse parti-
tions, and borne on a stout pedicel. According to Pro-
fessor Scribner, these sjDores germinate tlie following
spring by ^'sending out somewhat thickened tubes

(usually one tube issues from each cell),
wiiich, after attaining a length several
times that of the spore, joroduce several
minnte globose bodies on short and slen-
der stalks. These bodies, named spo-
ridia, are easily wafted from place to
place by the slightest currents of air, and
when they fall npon rose leaves where
there is moisture they send out slender
filaments, which probably bore their way
through the cuticle into the interior of
the leaf," where the mycelium is again
developed, and the disease is started for
another season.

Treatment. — Eose bushes should
be watched early in the season, and as
soon as any lemon-yellow spots are noticed
the affected portions should be removed
and burned. Raking up and burning at
the end of the season, the leaves beneath
any bushes that may have been affected
during summer, is advisable, on account
of the winter spores so destroyed. It is
well, also, to spray such bushes, and the
ground beneath, during winter, with a
solution of copper sulphate, or with some
other fungicide. Probably spraying with
the ammoniacal copper carbonate in spring, after the
leaves expand, would prove helpful if needed.

A good account of this fungus, illustrated with a
colored plate, may be found in the United States De-
partment of Agriculture, Report for 1887 (pp. 369-371).

FIG. 52.

WINTER SPOKE.

3IAGXIFIED.

THE EOSE PHKAGMIDIUM

117

The Rose Phragmidium

Phragmidiiim speciosum

The peculiar appearance of this disease when attack-
ing tlie stems of ro'^ei is well illustrated in Fig. 52 a.

bark of such

l.ie

Vfffi

stems is more or less
covered with irregu-
lar black patches, con-
sisting of vast num-
bers of the winter
spores of the fungus,
borne upon long slen-
der stalks, as seen,
much magnified, at h.
The spores themselves
are divided by trans-
verse partitions into
from five to seven
cells. The mycelium
of this fungus devel-
ops in the inner bark
and the cambium
layer of the stems,
but is believed not to
penetrate into the
woody tissue. Of
course it interferes
with the flow of sap,
and when, as often
a b hap])ens, it extends

FIG. 52. ROSE PHKAGMiDiuM. clcar arouud the stem,

a, Affected stem; 6, winter spores. it may JOrOVO fatal to

the plant. The mycelium is perennial in the stems,
living from one season till the next, so that when once
infested there is no way of ridding a plant of it. The

118

FUXGI AXD FUNGICIDES

only remedial treatment suggested is to cut aad burn
infested parts of bushes. Probably spraying or washing
the stems with the Bordeaux mixture will prove advan-
tageous in preventing the ingress of the parasite.

A short article concerning this fungus appears in
the report of the United States Department of Agricul-
ture for 1887, Pacre 372.

FUNGI AFFECTING FLOWERS

The Hollyhock Rust

Puccinia malvacearum

This fungus is a iiative of Chili, from whence,
about 1869, it was introduced into Europe, where it has
done much damage. It first appeared on hollyhocks in
this country in 1886, having been accidentally imported
into Massachusetts the previous year on another plant.
Since then it has gradually spread in various directions.
It appears in May and June, in the shape of yellow or
orange spots, on the leaves and stems of the holly-
hock. These spots occur especially on the under sur-
face of the leaves ; they increase rapidly in size, and the
yellow color gives way to a brown. The spots, or sori,
are composed of two-celled sj^orcs. When they are very
abundant they cause the plant to become sere and brown,
preventing, in whole or in part, the production of flow-
ers. A leaf showing the sori on the under surface is
represented in Plate XIII.

Treatment. — When this disease appears' in a new
locality for the first time the best method will be to pull
up and burn the affected jilants at once. Euroj^ean
gardeners have reported successful results from spong-
ing all diseased parts of the plants with a mixture made
by adding two tablespoonfuls of saturated solution of
permanganate of jootash to one quart of water. It seems
probable that thorough spraying with some fungicide
like the Bordeaux mixture or the ammoniacal copper
carbonate solution, would prove helpful. In any case,

119

120 FUXGI AXD FUXGICIDES

the fallen leaves and dead plants should be removed and
burned.

Two other hollyhock diseases commonly occur.
The more abundant is the leaf-spot, due to the fungus
Cercospora althmina. Leaves attacked by it show at
first small distinct spots, which rapidly enlarge, often
running together and destroying the entire leaf-tissue.
It affects 3'oung, as well as old, plants, and frequently
is very destructive.

The leaf -blight of hollyhocks is due to Phyllosticta
althceina. Affected leaves are usually not attacked in
so many places as by the leaf -spot, l^ut the injury in the
infested area is more severe, the tissues being destroyed
as the fungus spreads. Excellent illustrations of these
diseases may be found in the American Florist (Jan. 25,
1894). The use of seed from non-affected plants, and
spraying with Bordeaux mixture, are recommended as
preventive measures.

The Carnation Rust

Uromyces caryopMllinus

During recent years the growing of carnations —
appropriately called the ^^ divine flower" — has become
one of the most important branches of the floral indus-
try. In consequence, the fungous diseases of the plant
have received unusual attention, and effective methods
of preventing most of them have been discovered.

The carnation rust is the most important of these
diseases. It first appears on the stem or leaf as a pale
elevated pustule, over which the epidermis soon breaks,
hanging on the edges in a ragged condition, and reveals
a brown powdery mass which consists of the reproductive
spores of the fungus. Like the other rusts, this fungus
develops two kinds of spores, the iiredospores, which
may be likened to the conidia, or summer spores, of

THE CARNATION LEAF-SPOT 121

other fungi ; and the teleuto-spores, which are the rest-
ing or winter spores. There is little difference, to the
naked eye, except that the teleuto-spores are slightly
darker in color. The uredospores are the ones by which
the disease is rapidly propagated and spread. They may
be blown or washed from plant to plant, spreading infec-
tion rapidly. Carnations of all ages are liable to injury,
which is often so serious as to ruin large plantings.

Treatment. — The experience of a number of flor-
ists has shown that this rust can be prevented by the
use of the dilute Bordeaux mixture, supplemented by
careful hygienic methods. The application should be
made upon the first appearance of the disease, or even
before, if there is much danger of its presence, and
repeated at occasional intervals. Instead of the liquid
mixture, which it may not be desirable to use on plants
in blossom, a dry preparation is used by some growers.
It is made, as follows : ^^Six pounds sulphate of copper
dissolved in three or four gallons of boiling water, stir-
ring till thoroughly dissolved; with this liquid and just
enough added water, dry slake one bushel of lime (dif-
ferent limes require. a slightly varying quantity of liquid
to slake them.) Thoroughly dampen a tight wooden
box, and put in a layer of the lime and sprinkle with
the copper solution till it falls into a fine dust. Put in
another layer and sprinkle, and continue till the bushel
of lime is reduced to a dry powder." This powder is to
be dusted over the foliage. Sulphide of potassium — one
ounce to ten gallons of water — has also been successfully
used.

The Carnation Leaf=spot

Septoria dianthi

This is a widely distributed and troublesome dis-
ease. It appears on the leaves and stems in the shape
of a more or less circular purplish spot with a whitish

122

FUNGI AND FUNGICIDES

center, the latter often being dotted with black by the
fruiting portions of the fungus. The fungus penetrates
the stem rather deeply, often cutting off the supply of
nutriment to the flowers, and, consequently, preventing
their development. A plant injured in this way is rep-
resented in Fig. 53, from a photograph by Professor
Atkinson. The spores are produced in great abundance.

FIG. 53. CARJs'ATIOX INJURED BY LEAF-SPOT.

and distributed bv means of wind and water. Care in
watering, and the use of fungicides, are the best reme-
dial measures.

There are certain other carnation diseases, such as
the anthracnose, the leaf-mold, and the rosette, which
need hardly be discussed in this connection. Partial
accounts of them may be found in American Gardening
for April, 1893, where also the diseases treated of above

THE MIGNOXETTE DISEASE

123

are described. One of the fullest accounts of the carna-
tion rust, by Professor Arthur, occurs in The American
Florist, Feb. 18, 1892.

The Mignonette Disease

Cercospora resedce

Mignonettes frequently suffer from a disease which
may first be noticed, ^'^ either as minute pale spots with
brownish or yellowisli boi'ders — little sunken areas in

%^

FIG. 54. MIGNONETTE DISEASE,
a, Spore; 6, spore stalks ; e, germinating spore. Magnified.

the succulent tissues of the leaf — or as reddish discolora-
tions which spread over the leaf, and finally develop
into these pale spots or patches." These spotted areas
are portions of the leaf which the fungus has invaded
and destroyed. As the mycelium develops within the
leaf they increase in size, and finally involve so much of
the surface that the leaf wilts and withers ; the whole
plant sometimes looks as if it had suffered severely from

124 FUXGI AXD FUNGICIDES

drouth. Black specks develo23 on the surface of the
injured areas, giving it a granular appearance. These
specks consist of the fruiting spores of the fungus. The
young seed-pods are sometimes affected.

If one of the little black specks be looked at from
the side under a high power of the microscope it will be
seen to resemble Fig. 54, which represents a tuft of
fruiting threads after they have burst through the skin
of the leaf. At a is seen a spore borne on the summit
of one of these fruiting threads {h, h), while at e is seen
a spore in process of germination.

Treatment. — Mr. D. G. Fairchild made some ex-
periments in spraying the young plants with the Bor-
deaux mixture, from which he concluded that if the
young plants are carefully sprayed with the Bordeaux
mixture the trouble may be avoided. The spraying
should be repeated whenever the spots begin to show.

Literature. — The only American articles of im-
portance known to me are one by Professor A. B. Sey-
mour in The American Florist for September, 1887
(p. 38), and another by Mr. D. G. Fairchild, from
which the above quotation is made, in the report of the
United States Department of Agriculture for 1889
(pp. 429-432).

The Verbena Mildew

Oidium et^siphioides

This often proves a destructive enemy to verbenas
under glass, appearing on the leaves and young stems as
patches of white mildew. According to Professor L. H.
Bailey, it may be prevented by spraying with sulphide
of potassium (one-fourth ounce to a gallon of water)
about twice a week. Probably the ammoniacal copper
carbonate solution, or other copper fungicides, would
prove equally effective.

r

THE PETUN"IA BLIGHT 125

The Petunia Blijjht

Ascochyta petunice

Petunia leaves are sometimes affected by a blight,
which is likely to begin near the center and to spread in
all directions. Sometimes rings are produced on the
injured tissues. Like other fungi, this species repro-
duces by means of spores, which are developed in great
numbers. The early application of fungicides is sug-
gested as a preventive.

There are many other fungous diseases of flowers
and foliage plants, but the limits of the present work
prevent their discussion here. Illustrated accounts of
many of them have been published by Dr. Halstead and
others in The American Florist, Garden and Forest,
The American Agriculturist, and other journals.

IF'^I^T TV

Fungi affecting vegetables

FUNGI AFFECTING THE BEAN

The Pod=spot or Anthracnose

Colletotriclium lagenarium

Young bean pods, especially of the yellow or wax
varieties, are often affected by small reddish-brown
spots, slightly sunken beneath the surrounding area.
As the pods develop these spots increase in size, and
their centers become blackened. In course of time
many of them may run together to form long discolored
blotches upon the sides of the pods, and generally the
blackened centers eventually become of a dirty gray or
light brown color. The effect upon the pod of such an
attack is disastrous ; it is shrunken and out of shape,
and the beans within are dwarfed and shriveled.

This disease is seldom destructive, except during
seasons of rainy weather. It occurs in several European
countries, and has been found over a large portion of
the United States. It winters over, in part, by means
of diseased seeds, which, when planted, start the fungus
again, and it spreads rapidly when sound and affected
string beans are sent to market in the same receptacle.
This same fungus attacks melons, and other cucurbita-
ceous plants, causing a rind-rot. Consequently, beans
and melons should not follow each other in rotation, as
the spores in the ground will cause trouble.

While the attack of this fungus on the pod is most
noticeable, it does not confine itself to this part of the
plant. In case diseased beans are used for planting,
the attack may be noticeable as soon as the seed-leaves
come up, and may develop so rapidly as to injure the
9 129

130

FUXGI AXD FUNGICIDES

FIG. 55. BEAN PLANT ATTACKED BY ANTHRACNOSE.

THE POD-SPOT OR ANTHEACNOSE 131

stalk (Fig. 56) and kill the plant. In this way a fourth
of the seeds ^olanted are sometimes killed off. As the
leaves develop they are attacked, the veins becoming
blackened, and discolored spots appearing. Dots of a
light pink color appear on the middle of the spot shortly
after it has formed. A microscopic examination will
show that these dots consist of spore masses held together
by a mucilaginous substance, which is readily soluble in
water. When the enveloping mucilage is dissolved the
spores are set free, to be blown or washed about, or car-
ried to other plants by insects or other agencies.

Treatment. — Planting in a light soil, on high,
well-drained land, is one of the best preventives of this
disease. Experiments in New York have shown that it
is well worth while to examine the seed beans carefully
before planting and reject all that show signs of the dis-
ease. Then the young plants may be sprayed with
dilute Bordeaux mixture, to which soap enough has been
added to make a slight suds, applying first when the
plants are two weeks old, and repeating two or three
times at intervals of a week or ten days. Or soak the
seed in dilute ammoniacal copper carbonate solution.
In the case of string beans, where the pods are to be eaten,
the spraying must cease earlier than with those crops
where the beans themselves are to be harvested. The
immediate removal and destruction of all plants or por-
tions of plants which become affected is very desirable, as
every plant so left becomes a center of infection. They
should be taken away and burned or buried.

Literature. — The best article concerning this dis-
ease accessible to the American student was published
by Professor Scribner, in the report of the Department
of Agriculture for 1887 (pp. 361-364). It is illustrated
by an excellent colored plate. Professor Trelease pub-
lished an earlier account in the CuUivato7' and Country
Gentleman (October, 1885). Other articles of especial

132 ru]srGi axd fuxgicides

value, because of their accounts of remedial treatment,
will be found in the report of the New Jersey Experi-
ment Station for 1891, and in Bulletin Xo. 48 of the
New York Experiment Station. The latter account
contains a list of sixteen articles, in which the disease is
discussed.

The Bean Rust

Uromyces phaseoli

This is a decidedly different disease from the an-
thracnose of the bean. It commonly appears on both
surfaces of the leaves in the form of small, round, brown,
scattered spots, which at first are about the size of pin
heads. These soon give off a brown powder, which is
composed of the spores, or reproductive bodies of the
fungus. In the course of the season the brownness of
the spots changes to black. Often both brown and
black sj^ots may be found on the same plant at the same
time. The blackness simply represents a later stage of
development of the fungus. This disease is seldom
destructive, and little has been done in the way of reme-
dial treatment. Presumably spraying the plants with
Bordeaux mixture will prove a preventive.

The Bean Blight

In some parts of America still another disease has
proved destructive to beans. It appears to be due to
bacteria.- Mr. S. A. Beach says that ^'^in its early stages
this blight forms small pimples, which have a watery
appearance. These may occur on the pods, blossoms (?)
foliage or stems. They may or may not have a dull
red border, but do not have either the black color or
the sunken spots which characterize anthracnose. Mi-
croscopic examination in the early stages of the blight
failed to reveal the joresence of any mycelium, but bac-

THE LIMA BEAX MILDEW

133

teria were always present. In later stages saprophytic
fungi gained entrance through the diseased j)laces ai.d
hastened the destruction which the bacteria had inau-
gurated." The beans within the pods are also affected,
many of them being more or less discolored and disfig-
ured by the blight. Lima beans are also attacked by
what is supposed to be the same disease. So little is
known of this disease that the only remedial measures
at present to be suggested are the burning of diseased
vines, the selection of healthy seed, and crop rotation,

The Lima Bean Mildew

Phytopliora phaseoli

This fungus first attracted attention two or three
years ago, in the vicinity of New Haven, Connecticut,
where it was carefully studied
by Dr. Eoland Thaxter, who
has published an excellent
account of it. It does not,
as yet, seem to have spread
over a w'ide area, but it is
likely to do so within a few
years.

This mildew generally
first appears on the sides of
the immature pods as a whit-
ish, woolly spot, which, dur-
ing damp weather, increases
rajDidly in size. The threads
of the fungus penetrate the
pod, and may develop on its
outer surface until it forms a thick white coating, which
often completely envelops the j)od. The tissues of pods
so affected are, of course, ruined ; they shrivel, blacken
and decay. A similar injury to the young shoots is
often produced, and sometimes the leaves also are
affected.

a ^

FIG. 56. LIMA BEAN MILDEW.

«, Spoi'e and zoospores; 6, fruiting
tuft. Magnified.

134 FUNGI AND FUNGICIDES

This mildew is closely related to the Downy Mildew
causing potato rot, to which it is similar in life-history
and habits. The mycelium develops in the tissues of
the bean plant, and usually sends out its fruiting
branches through the breathing pores (or stomata).
The small oval. summer spores are produced npon the
tips of these branches, as seen in Fig. oG, h. These
spores generally germinate by means of the so-called zoo-
spores (a), m a way precisely similar to the germination
of the potato fungus spores described on Page 8. No
winter stage of the fungus is 3'et known.

Treatment. — All leaves, stems and other refuse
from the bean plants should be burned as soon after har-
Tcst as possible. Experiments in spraying with fungi-
cides have apparently not yet been tried, but the success
attending spraying for the related fungus on potatoes
indicates tliat good results are likely to be obtained in
this way. The ammoniacal copper carbonate would be
a good fungicide for the purpose.

Literature. — The most important account of this
disease is that published by Dr. Thaxter in the report of
the Connecticut Experiment Station for 1889 (pp.
167-171).

FUNGI AFFECTING THE BEET

The Beet Rust

^ Uromyces hetoe

In certain portions of the United States the rust of
sugar beets has done serious injury. It appears to have
originated in Europe ; and in America has been especially
destructive in California. Beets attacked by it become
dwarfed and discolored.

Professor L. H. Pammel, of the Iowa Experiment
Station, has recently published the following account of
the life-history of this fungus : '^Ifc is characterized by
having three stages — the aecidio (cluster-cup) stage, the
uredo (red-rust) stage, and the teleuto (winter) stage.
The -first, or cluster-cup stage, occurs on the leaves and
stems of seed beets. The cluster-cups contain chains of
orange-yellow spores. These germinate under favorable
conditions, sending out a little tube, which enters the
leaf through its breathing pores. On the inside it devel-
ops the mycelium between the leaf cells, sending into
the cells themselves small ^suckers,' which absorb their
contents. After a time this mycelium produces, in cer-
tain places, spores of another kind called the uredo
spores, which are pushed out through the skin of the
leaf. These spores soon germinate and spread infection
to other plants. Late in the season still another kind
of spore is found. It is known as the teleuto-spore, or
winter-spore. These do not germinate until the follow-
ing spring, when a tube known as the promycelium is
pushed out. This tube is branched, and bears small

135

130 FUN^GI AXD FUXfilCTDER

lateral bodies, known as sporidia. These germinate,
and when fallins: on the proper host, prodnce the secid-
ium stage, thus completing the cycle of the year."

Treatment. — The development of the disease upon
seed beets, where alone, according to some authorities,
the first stage is passed, may probably be prevented by
spraying with some of the copper fungicides — the Bor-
deaux mixture, for example. The removal and burning
of affected leaves is also recommended.

Literature. — A good account of this disease, with
figures of the spores, may be found in the United States
Department of Agriculture report for 1887 (pp. 350-353).
It has also been discussed by Dr. Halsted, in the Bul-
letin of the Iowa Agricultural College for 1888 ; and by
Professor Pammel, in Bulletin Xo. 15 of the Iowa Ex-
periment Station (pp. 235-230).

The Beet Leaf=spot Disease

Cerco8pora beticola

This diseace appears to be more widely prevalent in
America than the leaf-rust. It first a^^pears on either
the upper or lower surfaces of the leaf, or on both, in
the shape of small pale brown, more or less circular
spots, with lighter colored margins. At first these
spots may be no larger than a pin-head, but they grad-
ually increase in size, and often run together and form
large discolored patches. As the spots grow older they
become darker colored. AVhen the attack is serious
much injury may be accomplished in lessening the size
of the crop. This disease attacks both the sugar beets
and the ordinary varieties of cultivated beets. It has
also been found upon various varieties of mangolds.

The affected tissues are shrunken by the action of
the fungus. By the aid of a lens one can see, here and
there on the diseased surfaces, the long, slender, cylin-

THE BEET LEAF-SPOT DISEASE 137

(Irical spores projecting outward from ilic breathing
pores, or through ruptures in the skin. Each of these
spores is divided by transverse partitions into several dis-
tinct cells, and each of these cells is capable of sending
out a germinating tube to start the disease in a new
place. In autumn these spores fall to the gronnd with
the foliage, and remain there over winter in condition to
infect a new crop the following spring.

Treatment. — The last statement in the preceding
paragraph indicates the desirability of rotation of crops
in preventing this disease. In case the same ground
must be used for beets several successive seasons, the
leaves should be removed when the crop is gathered,
and burned, or composted, and the resulting compost
applied to some other crop than beets. If these meas-
ures are not sufficiently successful, it is probable that
spraying with the common fungicides will prove an effi-
cient preventive.

Literature. — The most important article concern-
ing this disease yet published in America occurs in Bul-
letin No. 15 of the Iowa Experiment Station. It is by
Professor L. H. Pammel.

FUNGI AFFECTING THE CABBAGE AND

CAULIFLOWER

The Club Root

Plasm odiopliora brassicce

The club-root of cabbage, cauliflower, turnip and
other cruciferous plants, is well known to most garden-
ers in the eastern and central States. It is also found in
many parts of Europe, having been known in Scotland
for more than a century. The disease is sometimes
called '-'clump foot," ^'club foot," and '^fingers and
toes;" it often does great damage, sometimes destroy-
ing entire crops. The trouble has been attributed to
various causes, but it is now definitely established that
the agency chiefly concerned is a low form of fungus —
one of the slime-molds — the vegetative portion of which
does not even develop mycelium threads, but grows as a
semi-liquid slimy mass. This gains access to the tissues
of the young roots and develops in the cells, causing the
tissues to become malformed in various ways. After
developing in this way awhile the mold produces innu-
merable spores, w^hich are set free by the rotting of the
root tissue, and left in the soil. Here they germinate
by the production of zoospores, which remain in the
soil apparently indefinitely, and penetrate — when oppor-
tunity offers — the thin-walled cells of roots and rootlets,
thus continuino: the cvcle of existence.

The disease commonly attacks seedlings in the seed
bed. Such plants begin an abnormal root-development,

138

\ -

THE CLUB ROOT

139

a few roots becoming greatly swollen, as shown in Fig.
57, and the leaves, instead of having the dark green
color of healthy foliage, become pale green or yellowish.

FIG. 57. CLUB ROOT OF OABBAiJK.

Sujch an injury, of course, prevents the proper develop-
ment of the plant, which becomes worthless.

. The injury to other crops than cabbage is often
severe. Cauliflower is frequently attacked with fatal,
effect, as may be seen in the photo-reprorlnction in Fig.

140

FUNGI AND FUNGICIDES

58, while turnips commonly suffer in a most disastrous
manner (Fig. 59). But cultiyated crops are not the only
hosts of the fungus — a fact which makes it still more

FIG. 58. CLUB ROOT OF CAULIFLOWER.

difficult to contend against. Various weeds belonging
to the cruciferous family are also attacked by the club
root fungus. Shepherds' purse, for example, is com-

THE CLUB ECOT

141

monly infested, the roots presenting the appearance
shown in Fig. 60. Because of this, crop-rotation, which

FIG. 59. CLUB KOOT OF TURNIP.

SO often proves serviceable in checking fungous diseases,
may possibly become ineffectual ; but this is, neverthe-

142

rUKGI AND FUNGICIDES

less, one of the best preventive methods. Crops on
land which has previously been planted to cabbages or
turnips are most liable to suffer, but the disease is said

FIG. 60. CLUB ROOT OF SHEPHERD'S PURSE.

sometimes to appear on new land. Crops on limestone
soils are usually quite free from attack.

Clean farminsf, involvinsf the removal and destruc-
tion, by burning, of all refuse of the cabbage or turnip

THE CLUB ROOT 143

field, together with constant crop-rotation, are the chief
safeguards against the club root fungus. The only way
to lessen attack is to use preyentive measures ; for when
once the fungus has obtained a hold upon the plant, it
cannot be gotten rid of. It is probable that methods of
preventing it from attacking seedlings in the hotbed can
readily be found, but few definite experiments on the
subject seem yet to have been made in America. Eng-
lish writers assert that if the soil of the seed bed be
treated with carbon-bisulphide before the seeds are
planted, the traces of the fungus in the soil will be de-
stroyed, and the seedlings escape attack. If many of
the seedlings in the seed bed show the disease, the whole
lot better be pulled up and burned, and other plants
obtained. The use of lime at the rate of seventy-
five bushels to the acre, has been recommended as
a preyentive, and, apparently, backed l^y practical
experience.

Excellent accounts, in which the life-history of this
fungus is fully discussed, occur in the Journal of My-
cology (v. VII, pp. 79-88), by A. C. Eycleshymer ; in
Ward's Diseases of Plants ; and in Bulletin 98 of the
New Jersey Station, in which Dr. Halstead first pub-
lished the illustrations appearing above. An effect yery
similar to club root is often produced on the roots of a
great variety of plants by the little worms called
Nematodes.

FUNGI AFFECTING CELERY

The Celery Blight

Cercospora apii

The common blight of celery, sometimes incorrectly
called the rust, is a destructive and widespread disease,
which appears from the middle to the last of summer.

Its presence is usually
first seen in the shape
of small, irregular, yel-
lowish-green spots, less
than a quarter of an
inch in diameter, upon
the leaves. These sjiots
increase rapidly in size,
and soon chano;e to a
brown color. In a short
time they so spread as
to form great blotches,
involving a large por-
tion of the leaf, which
may finally wither and
die. The fungus caus-
ing this disease repro-
duces by means of elon-
gate spores. When one
of these falls upon a
moist celery leaf it ger-
minates by sending out
a long tube, which penetrates the leaf, and develops the
mycelium among the cells. Here it continues growing

144

FIG. 61. CELERY LEAF SHOWING
BLIGHT.

THE CELERY BLIGHT

145

for some time ; then certain branches of the mycelium
are pushed through the breathing pores, or stomata, of
the leaf, and produce on their tips the spores. Fig. 62
J, represents a sectional view of a leaf having the m3^ce-
lium developed among the cells, and the spore-producing
branches coming out through a breathing pore. In a,
of the same figure, two spores in process of germina-

1300^3

a h

FIG. 62, CELEKY LEAF-SPOT.
a, Spores germinating; 6, section of leaf showing fungus. Magnified.

tion are represented. No winter spores have yet been
discovered.

It has been found, in some localities, that celery
growing in the shade is seldom affected by this fungus.
Hence it is recommended that, unless fungicides are to
be employed, as advised below, the celery bed be placed
in situations shaded by trees ; or that it be artificially
10

146

FUIfGI AXD FUNGICIDES

shaded by screens of lath, or similar material. It is
important, also, that refuse leaves aSected by the dis-
ease be gathered and burned.

Literature. — Articles concerning this fungus occur
in the United States Department of Agriculture rej^orts
for 1886 (pp. 117-120) and 1888 (pp. 308-399) ; Bul-

FIG. G3. CELERY LEAF INJURED BY LEAF-BLIGHT.

letin 2, New Jersey Experiment Station, and 1891 report
(pp. 250-253) ; also Bulletin No. 51, New York Experi-
ment Station.

The Celery Leaf=blight

Septoria petroselini, var. apii

This is a disease somewhat similar to the blight
already described, which attacks all portions of the cel-
ery plant except the root. Its presence is commonly
first shown by the appearance, on the leaves or stems, of
watery areas, which soon afterwards become spotted

THE CELEKY LEAF-SPOT 14,1!

with smtill black dots, projecting slightly above the
cuticle of the i)lai]t. These dots consist of the spores,
or reproductive bodies of the fungus. A leaf injured by
this malady is represented in Fig. 63. The black spots
appear also on the stems and seeds of the fruiting plant,
as shown in Plate XV, and it seems probable that the
fungus is disseminated by means of such diseased seeds.
The malady commonly appears in the seed-bed, and it
is, at least, a safe precaution not to plant seeds so spot-
ted. Those wiio harvest celery seed should not gather
from plants so diseased.

Accounts of this malady occur in report of New
Jersey Experiment Station, 1891 (pp. 255-256), and
Bulletin 2 ; report Massachusetts Experiment Station,
1891 (p. 231) ; and Bulletin No. 51, New York Experi-
ment Station. Still another celery leaf fungus, belong-
ing to the genus Phyllosticta, has been described by
Dr. Halsted.

Treatment for Celery Diseases. — The most
promising method of preventing these celery diseases is
that of spraying the young plants with dilute Bordeaux
mixture, beginning soon after they come up in the seed-
bed, and continuing the treatment at intervals of ten
days or two weeks, at least until transplanting time.
Later sprayings with either the Bordeaux mixture or
the ammoniacal copper carbonate solution, are advisable,
if the disease appears in the field. Such sprayings may
be made, according to some experiments, up to the time
of blanching, without danger of injuring the plants for
food, but it would be better, usually, to discontinue the
treatment some weeks earlier. Eefuse celery should not
be left upon the field, especially where the same ground
is to be planted to celery the following season.

p- -^

PlvATE XV. MAGNIFIED VIEW OF CELERY SEED A>.D PORTIONS OF
STEMS DOTTED WITH FUNGUS OF LEAF-BLIGHT.

THE SOFT EOT OF CELERY

149

The Soft Rot of Celery

The central portions of celery plants are frequently
attacked by a disease which causes what growers call the

^^soft rot." A portion of a plant
so affected is represented in Fig.
64. This appears to be due to
minute bacteria. It esj^ecially
attacks plants banked or stored in
wet places, and sometimes causes
serious losses. Golden sorts ap-
pear to be most liable to the mal-
ady. Dr. Halsted advises, as a
preventive, keeping celery dry or
placing it under pure water. His
discussion is found in the 1892
report of the Jew Nersey Experi-
ment Station. The injury of this
malady is not confined to the core.
The leaves are also affected ; they
become spotted with brown, the
spots often having the watery ap-
pearance that bacterial blights
are likely to produce. Instances
are on record in which large crops
have been ruined by this disease.

FIG. 64. SOFT ROT OF '^ i , .1

cEi^ERY. It seems quite possible that the

bacteria causing this malady are the same as the ones
causing tomato and potato blight and similar diseases.

FUNGI AFFECTING THE ONION

more or less

The Onion Mildew

Peronospora schleideniana

This disease appears upon the tops of onions as a
grayish, moldlike, velvety coating, which is followed by

ilting of the affected leaves (Fig. 65).
Seed onions seem to be the most liable
to injury, and crops grown on low, damp
ground, are more subject to attack than
those in higher, drier situations. The
fungus has been known in Europe as a
serious enemy, for many years, but has
only been recognized in America for
about a decade. The threads of the fun-
gus push about between the tissue cells
of the liost, destroying their contents
and. causing the collapse of the leaves. Certain branches
are sent out through the breathing pores of the leaf, on
which the spores are developed, as shown in Fig. 66.
The cpores are pointed-oval in shape, and have a faint
purplish tinge ; they are easily detached, and wafted or
washed from plant to plant by wind or water. Under
favorable conditions they quickly germinate, entering
the tissues through the breathing pores by means of a
short germ-tube. Thus the fungus may spread rapidly.
Besides these conidia, or summer spores, the fungus
develops certain winter spores, called oospores, by
means of which it passes the winter. These are pro-
duced within the tissues, of the host-plant, and carry

150

FIG. G5. ONION
LKAF AFFECTED
WITH MILDEW.

THE OXIOX SMUT

151

the fungus oyer from season to season. They have a
thicker wall than the conidia, and are spherical rather
than oval.

Treatment. — The destruction, by fire, of all refuse
tops in which the resting spores may pass the winter, is
one of the most important remedial measures. Such
tops should never be turned under unless the ground is
to be used for some other croj) the following year.
Rotation of cro-ps will probable pro'.o the most success-

FIG. GG. DEVELOPMENT OF SPOKES. MAGNIFIED.

ful general remedy. Where the nse of fungicides is
practicable these, no doubt, can be employed to good
advantage.

Literature. — Professor William Trelease published
an excellent account of the onion mildew, in 1883, in
the first report of the Wisconsin Experiment Station.
Dr. Thaxter also has a good discussion of it in the report
of the Connecticut Station for 1889 (pp. 155-158), and

152 FUXGI A^'D FUNGICIDES

Professor Dudley a notice of it in Bulletin 15 of the
Cornell Station.

The Onion Smut

Urocystis cepulce

The smut of onions has been known to occur in
America for about thirt}- years, although it was not defi-
nitely named and described by botanists until 1877. It is
widely distributed in the United States east of the Mis-
sissippi river, and appears to be especially destructive in
the onion-growing regions of Connecticut. Dr. Roland
Thaxter, recently mycologist to the experiment station
of that State, has carefully studied the disease, publish-
ing an excellent illustrated account of it in his report
for 1889, from which the accompanying figures, and
much of the following information, are taken.

According to Dr. Thaxter, ''the presence of smut
in onions is first indicated by one or several dark spots
at different heights in the leaves of seedlings, which are
seen to be more or less opaque when tbe plant is held up
to the light. These dark appearances may be seen in
the first leaf, before the second leaf has begun to develop
at all, and are more commonly found just below the
*'knee ;" thous^h they sometimes occur above it. After
a time, usually wiiile the second leaf is developing, lon-
gitudinal cracks begin to appear on one side of these
spots, which widen and show within a dry, fibrous
mass, coyered with a black, sooty powder made up
wiioUy of the ripened fruit or spores of the fungus,
which are blown or washed out onto the ground. In
some cases the smut may appear only toward the upper
end of the first leaf, and become cut off from the main
body of the plant by the withering of the former. In
such a case an onion which has shown smut in its first
leaf appears, in some instances, to recover, showing no

THE ONION SMUT

153

signs of smnt in its subsequent growth ; but, as a rule,
the same dark appearance shows itself in the second leaf
and those subsequently formed, and if the seedling is
pulled up and examined, the whole
plant will be found to be pervaded
by the disease, to a greater or less
extent. Plants thns diseased, espe-
cially if the soil is dry, very com-
monly succumb early, dying while
in the second or third leaf. The
stronger plants, however, especially
if the ground is moist, are able to
resist the smut sufficiently to make
a considerable growth, and many
survive even up to the time of har-
vesting. Fig. G7 represents such an
onion rednced to one-third its nat-
ural size, and is a typical example
of the appearance presented by smut-
ted onions that have survived until
midsummer. In such specimens the
smut shows itself by black eleva-
tions upon the bulb, running down
to its very base, and extending up
ward into the leaves, the outer of
which, in the present instance, liave
split open, showing the characteristic
sooty powder composed of spores
mingled with the stringy mass of
dead leaf tissue. As a rule such

, T -ii 1 • FK;. 67. ONION AFFECTED

onions always die, either drying up ^^. ^^^^^^ one-third
or rotting soon after they are natural size.
pulled." "When onions are grown upon the same land
for several successive seasons the smut, after it once gets
started, gradually increases, until, at the end of five or
more years, the soil is so full of smut that the field gen-

154

^U^^GI AXD FUNGICIDES

erally must be abandoned and some other crop substi-
tuted. But even then the smut remains in the soil sev-
eral years — according to some observers, as many as
twelve — in such a condition tJiat onions cannot be
safely planted.

The black powdery masses that develop upon onion
leaves affected by smut consist of the spores, or rejjro-
ductive bodies of the fungus (Fig. 68 a). They are blown
or washed into the soil, where, after resting for a period

— sometimes until the
following spring, some-
times longer — they ger-
minate by sending out
a tube (b), which soon
develops a number of
secondary spores, or spo ■
ridia (Fig. 68 a;). These
sporidia themselves have
the power of germinat-
ing, sending out a short
tube (c), which enters
the young plant just
infection apparently
occurs before the plant has appeared above ground ; and
while, as just indicated, it 2:)robably is usually due to the
germinating sporidia, it is also probable that it is some-
times directly due to spores which do not develop spo-
ridia. After the fungus has once gained access to the
young onion plant, the development of mycelium begins,
and continues until a new crojD of spores is produced.

Local Dissemination. — Dr. Thaxter states that
^^the local dissemination of smut is due to four princii^al
causes. First, through agricultural implements ; plows,
harrows, weeders, rakes, etc., which spread the soil con-
taining smut spores, both by scattering the surface earth
over a smutted field, and, unless they are thoroughly

FIG. 68. 0>"ION SMUT.

a. Spore; 6, spore germinating; c, sporidia
germinating. Magnified.

starting from the seed. This

THE OXIOX SMUT 155

cleaned, by carrying earth containing smut spores into
fields subsequently worked upon. Secondly, through
the adherence of the same smutted earth to the feet of
men and farm animals, and its consequent transportation
from one part of a field to another, or to different fields ;
an agency by no means unimportant. Thirdly, the
smut spores may be readily washed, with surface earth,
fi'om higher to lower ground, as is a matter of common
ol)servation. Fourthly, popular opinion to the contrary,
the spores being practically imponderable, may be readily
blown, with other dust-like material, either about the
same field, or into adjoining fields. The reason that
this mode of dissemination is of less importance than
some others lies, probably, in the fact that the spores
being formed and making their exit from the onion com-
paratively near to the ground, are readily washed into
it by rain, and have little opportunity for blowing
directly into the air, as is the case with corn smut, for
example."

Treatment. — The simplest method of avoiding
injury by onion smut is to transfer the planting to new
land whenever the disease becomes destructive. But of
course this is only applicable either where one grows
only a comparatively small number of onions, or has a
lar^'e amount of land.

It has already been stated that infection by smut
apparently takes place before the young plant appears
above ground. In the case of corn and other grain crops
affected by various species of smut, the fungus enters
the plant when very young. These facts would lead us
to suppose that if young onions were started in soil free
from smut, and then transplanted to smutty soil, they
would escape the disease, because the period of infection
has been passed. And such is said to be the case with
transplanted seedlings. Consequently, in the practice
of transplanting onions, — which is highly recommended

loG FUXGI AXD FUXGICIUES

by leading horticulturists for other reasons than this, —
there is a sim2:)le and efficient remedy. Concerning the
j^ractical value of transplanting, a word further may be
said. Ex})eriments made at the Ohio Experiment Sta-
tion, by j\[r. W. J. Green, indicate that by starting
onions in forcing houses or hotbeds the yield may be
nearly doubled, without involving any more labor.
Concerning the cost of cultivation, Mr. Green says :

^'The difference in cost of cultivation was consid-
erable, the ratio being about one to two in favor of the
bed of transplanted onions. At the first weeding both
beds were weedy, but while the weeds were as large as
the onions in the bed where the seed was sown, making
weeding difficult and slow, the task was comparatively
easy in the other bed. At the second weeding it was
necessary to remove many of the small onions in the
bed where the seed was sown, an oj^eration which is
equivalent to an extra weeding. The work of weeding
was but one-half on the bed of transplanted onions that
it was on the other bed. Counting the extra trouble of
growing in the greenhouse and transplanting, the work
on the two beds was about the same for the whole sea-
son ; that is, transplanting adds nothing to the cost of
growing the crop, aside from the necessity of a green-
house, hotbed or cold-frame, in any of which the i^lants
can be started.

*'The difference in the time of ripening was about
one month, in favor of the transplanted onions, making
it possible to use them for bunching, and also to market
the crop at an earlier date than could be done with those
sown in the open ground. The yield of the transplanted
onions was about double that of the others."

Experiments by Dr. Thaxter indicate that possibly
flowers and sulphur and air-slaked lime mixed together
in equal parts, and sowed with the seed, may have a pre-
ventive effect. The same authority says that '^ill refuse

THE 0>s^lON SPOT DISEASE 157

of whatever kind iluit is left, on the field should be
burned as soon as practicable, and, although onion land
is usually kept so clean that it cannot be burned over in
the fall, this practice will be found very advantageous
when it is possible. At the second and subsequent hand
weedino^s all onions which show smut in the second or
third leaf should be pulled, collected in a basket or other
convenient receptacle, and burned at once. This prac-
tice involves very little trouble, and the folly of leaving
the larger smutted onions to discharge crop after crop of
spores upon the ground, as the leaves successively
mature, is apparent ; especially when the enormous
number of spores thus formed is considered. It is
hardly an over-estimate to say that a single large onion
may mature during a season something like a cubic inch
of smut, which means between one and two thousand
millions of spores, each capable of producing a smutty
onion in the following season."

Literature. — Dr. Thaxter's article so freely quoted
in the above account, will be found in the report of the
Connecticut Agricultural Experiment Station for 1889
(pp. 129-153). It contains numerous references to the
European literatui'e of the subject. An earlier article,
by Professor W. G. Farlow, will be found in the report
of the Massachusetts State Board of Agriculture for
1876-77 (p. 164).

The Onion Spot Disease

Vermicularia circinans

This is a fungus which has been described as inju-
rious to white varieties of onions after they are housed.
It starts in the field on part of the bulbs ; these produce
many spores, by means of which it is propagated in the
bins when the conditions are favorable ; that is, when
the atmosphere of the storage room is warm and moist.

158

FUXGl AXD FUXGICIDES

The disease appears in the field as a blackish growth on
the outer bud scales. It is not noticeable at first, and
when closely examined will be seen to consist of a cen-
tral dot or ring, surrounded by larger rings. During
damp weather the black growth develops rapidly, some-
times in the form of circles, and sometimes simply
spreading without circles, as in Fig. 60 a. AYhen the dis-

ly-^c

II'

\ '

a

FIG. 69.
a, Spot (liseafe of onions; b, spores.

ease first appears it only affects the outer scales, but
later it penetrates deeper and causes rot.

When highly magnified tlie black specks on the
bulb scales resemble Fig. 69 b. Each consists of a mass
of mycelium having long, black, pointed bristles, around
the bases of which the small, slightly curved spores are
produced in great numbers. These spores are easily
blown upon surrounding bulbs, where they may germi-
nate and start the disease again.

Treatment. — One of the best safeguards against
this disease is to put dry onions in dry bins, in cool and
dry storerooms. The onions should not be allowed to

THE OKION SPOT BISEASi:

159

heat at all, and bins which have contained diseased
onions should be disinfected by spraying or dusting with
some fungicide before they are again used. It has been
suggested that sprinkling the bulbs with dry, air-slaked
lime might prevent the spread of the disease.

Dr. Thaxter's article upon this disease may be
found in the report of tiie Connecticut Experiment Sta-
tion for 1889 (pp. 163-165).

FUNGI AFFECTING MELONS AND

CUCUMBERS

The Cucumber Mildew

Plasmopara cubensis

In America this disease has been recognized as a
destructive enemy of cucumbers and other cucurbitaceous
plants for only three or four years, but it is already
widely distributed, and in many places has done much
damage. The fungus attacks the leaves in a manner
somewhat similar to the attack of the downy mildew of
the grape. The mycelium, after entering the leaf from
a germinating spore, develops between the cells, and
sends suckers into the cells to absorb their contents. In
due time this mycelium sends branches out through the
breathing pores of the leaf, on the tips of which are
jH'oduced the spores. The injured leaves turn yellowish
or brown in spots, and if the attack is severe, are finally
destroved.

The destruction of all refuse leaves that may have
been infested, and spraying with fungicides, are the best
remedial measures. A rather full account of the fungus
may be found in the eighth report of the Massachusetts
Experiment Station (pp. 210-212; 1890), and in Amer-
ican Gardening, April, 1803.

The Bacterial Blight

This disease has been esj^ecially troublesome in the
Southern States, where it has done much damage to the
melon crop. It is also destructive in the truck-growing

160

THE BACTEEIAL BLIGHT

161

regions of the North, and it is possible that it is due to
the same germs as the bacterial blights and rots of vari-
ous otiier vegetables, such as celery, potato, tomato, etc.
*^Soon after the plants are up, and usually by the time
they have reached out a foot or so u^^on the ground, the
trouble begins. The stem may become moist, in a man-

no. 70. CUCUMBER LEAF AFFECTED WITH MILDEW.

ner to suggest what is termed ^ water core' in apples.
This may be close to the base of the plant, or midway
between that point and the tip of the vine. Sometimes
one leaf-stalk decays first, and the disease spreads from
it to other parts. Occasionally the free young end melts
away with the trouble. When tissue that is freshly dis-
eased is examined, it is found swarming with bacteria,
11

162

FUXGI AXD FUXGICIDES

and no other cause for the disorganization is to be seen.
Not unfrequently the leaves become spotted — that is,
certain areas decay and fall away. If a leaf freshly
affected is held toward the light, the diseased places
may be easily detected, by the peculiar discoloration.

FIG. 71. MUSKMELOK LEAF SHOWING BACTERIAL BLIGHT.

being due to the excess of moisture — a sogginess, so to
speak." (Halsted.)

Effective preventive measures for this vexatious mal-
ady have yet to be found. Presumably rotation of crops
will prove an important method, but if the same germs
affect many widely separated plants, a specially devised
rotation may be required.

IHE MELON LEAF-SPOT

163

The Melon Leaf=spot

A muskmelon leaf injured by a fungus belonging to
the genus Phyllosticta, is represented in Fig. 72. It
cjauses light colored spots, which may eventually break

FIG. 72. MELON LEAF-SPOT DESEASE.

away and give the leaf a very ragged appearance. The
fungus reproduces by means of small spores, which are
developed in great abundance. Presumably spraying
with fungicides will have a preventive effect.

FUNGI AFFECTING THE POTATO

The Downy Mildew, or Late Blight

Phytophora infestans

A sufficiently full account of this disease has already
been given in the Introduction (pp. C-10). A large pro-
portion of the potato maladies in the United tStates have,
until lately, been attributed to this fungus ; but recent
observations indicate that other agencies are at work —
particularly the fungus known as Macrosjwrium solani,
and apparently certain bacteria. The downy mildew
disease has been called, by Professor Jones, of Vermont,
the ''late blight," to distinguish it from the "early
blight," caused by the ]\[acrosporium. Tho late blight
fungus generally appears rither late in tlie season; and
icS attack is frequently sudden and fatal, affected plants
Ix'inGf entirely destroyed in a few days, 'j'he tubers are
also commonly affected, rotting and producing", during
I he process, afoul smell. This disease is most destruc-
tive during warm, moist weather, at such times spread-
ing very rapidly. It commonly begins as a single spot
en a leaf, from which it spreads throughout the plant,
end produces on the lower leaf-surface a mildew-like
growth, to be distinguished by the naked eye. This dis-
ease can be prevented by spraying several times with the
Bordeaux mixture.

The Early Blight, or Leaf=spot Disease

Macrosporium solani

This disease appears early in summer in the shape
of small brown, brittle spots, scattered over the leaf.

164

THE BACTERIAL BLIGHT 165

Careful inspection shows that their upper surfaces are
more or less roughened by darker areas rising above the
dead gray tissue. The spots gradually enlarge, and
finally run together to form large brown patches, the
intermediate tissues becoming yellowish or sickly green
in color. The entire plant finally withers, and dies long
before the proper period, the tubers being small — gen-
erally less than half full size. But the tubers do not rot
and are of good quality. This fungus has proven diffi-
cult to study in the field, the spores being produced
only on part of the affected plants. It winters over in
the spore stage on the dead vines.

The Bacterial Blight

Besides the two maladies alreaciv discussed, there is
a potato disease due to bacteria, although it is probable
that the Macrosjiorium blight has frequently been attrib-
uted to these organisms. Bacteria often develop in
tissues invaded by the fungus just named ; but there are
good reasons for believing that a genuine bacterial
trouble frequently develops in all parts of the plant. It
generally starts from the seed planted, which becomes
rotten. The vines die prematurely, often wilting rather
suddenl}^ and the young tubers decay. This disease is
more troublesome in southern latitudes than at the
north.

Treatment of Potato Diseases. — A large num-
ber of experiments in many sections of the United States
have shown that these various maladies may be pre-
vented by spraying with the Bordeaux mixture. It has
been repeatedly shown that vines thus sprayed remained
in a healthy normal condition long after the untreated
vines were dead, and that, consequently, the tubers
developed to a much larger size, with a greatly increased
yield. The results of an experiment of this kind, at

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m

i^^BHvr* '^'^

cl

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03

O

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THE BACTERIAL BLIGHT

167

the Uliode Island Station, are shown in Plate XVI,
which is reproduced from a photograph taken August
20th. '^The two rows in the center of the figure were
not treated with the mixture, consequently the leaves
all blighted and withered up soon after August 1st, leav-
ing only the bare, dead stems when the photograph was
taken ; while the leaves and vines in the rows on either
side, which had been sprayed with the Bordeaux mix-
ture, were fresh and green."

The effect upon the tubers, of treatment with Bor-
deaux mixture, as it resulted in some experiments by
Professor Jones, of Vermont, is shown in Fig. 73. The

a

h

FIG. 73.
a. Yield of unsprayed plot; 6, of sprayed plot.

treated vines vielded marketable tubers r.t the rate of
two hundred and ninety-one bushels per acre, while
those untreated yielded only at the rate of ninety-nine
and one-half bushels per acre.

As a general rule, the. first application of Bordeaux
mixture may be made when the vines are about one-third
grown, or earlier if signs of disease api:>ear. Repeat the
application when it is washed off — in about a fortnight

168 FUXGE AXD FUXGICIDES

usually. Add half a pound of London purple or Paris
green to each barrel of the mixture whenever the Col-
orado beetles threaten injury.

The Potato Scab

Oosjjora scabies

The ^^scab" of potatoes is familiar to every experi-
enced farmer. Like the pear bli^G^ht, the theories con-
cerning its cause have been many and varied ; but the
recent investigations of Messrs. Thaxter and Bolley have
established, with considerable certainty, that the injury
is reallv due to the attacks of a low form of funo;us life,
which develo2:)3 in the tissues of the growing tubers.
Two forms of scab, the "deep scab" and the "surface
scab," have been recognized by some writers, but there
is a strong j^robability that these are simply different
phases of the same injury. At any rate, there is little
difference, from a j)i'actical standpoint, and they will
not bo separately discussed hero.

It has often been noticed that scabby potatoes are
more abundant in fields heavily fertilized by barnyard
manure. This is now believed to be largely due to the
fact that if scabby potatoes are fed to stock, the spores
of the fungus can pass through the alimentary canal
uninjured, and c^in multiply abundantly in the manure
heap. Consequently they will be transferred to the field,
and when the potato tubers are developing, will attack
them and produce the injury.

The fungus-producing scab is an obscure one, which
botanists have studied only recently. It can generally
be seen on partially developed scabby jiotafcoes, in the
shape of fine white threads running over the surface.
It reproduces by means of sj^ores. Repeated experi-
ments have shown that if scabby potatoes are planted, a
large percentage of the resulting crop will be scabby.

THE POTATO SCAB

169

Professor II. L. Bolley has shown that what is probably
this same disease occurs also on beets planted on j^otato
ground.

Treatment. — Dr. Roland Thaxter, after seyeral
years of careful study, summarizes the preyentive meas-
ures to be taken against this disease as follows : (1) The

FIG. 74. POTATO INJURED BY SCAB.

seed must be free from any scabs. (2) Land wliicli has
produced scabbed cro]3s in previous years, either of pota-
toes or of beets, or has been fertilized with manure from
scab-fed stock, must not be planted to potatoes. (3)
Scab potatoes should neyer be fed to stock, under any

170 FUXGI AND FUNGICIDES

circumstances, unless they have been thoroughly cooked,
even if the land on which the manure is to be used is
not to be cropped with potatoes at once. (-4) In gen-
eral, any fertilizer is to be preferred to barnyard manure
for potatoes, whether the stock has been fed with dis-
eased potatoes or not. (5) If it is suspected that a crop
is scabbed, it is of great importance to dig the potatoes
as soon as possible after tbey are mature, since the seal-
spots increase in size, and deepen, as long as they are
left in the ground, and what is at first a comparatively
slight surface injury may be sufficiently extended to ren-
der tubers worthless, which would otherwise have been
marketable.

Experiments at the Korth Dakota Station, by Pro-
fessor Bolley, show that the disease may be prevented by
soaking the seed in a weak solution of corrosive subli-
mate. Concerning its use, he says: ''One wishing to
try the corrosive sublimate treatment, if to no greater
extent thai* to assure the raising of healthy, smooth
potatoes sufficient for seed the following year, will find
it best to proceed about as follows : Procure an ordinary
barrel, and fit into the base a common wooden faucet.
Purchase of a druggist two ounces of finely pulverized
corrosive sublimate {Mercuric licliloridc). Empty this
all into two gallons of hot water, and allow it to stand
over night, or until, apparently, all dissolved. Place in
the barrel thirteen gallons of water, then pour in the
two gallon solution. Allow this solution to stand in
the barrel four or five hours, during which time it is
several times thoroughly agitated, to insure equality of
solution before using. Select as fair seed potatoes as
possible, wash off all the old dirt, and immerse as many
as you can or wish to treat at one time in the solution
one hour and thirty minutes. At the end of this time
turn off the solution into another vessel. The same
solution may thus be used a number of times, if wished.

THE POTATO SCAB 171

After drying, the potatoes may be cut and planted as
usual. Plant upon ground that has not previously borne
the disease. The potatoes may be cut before treatment
if wished.

"Caution: — The corrosive sublimate is a strong-
poison, and too great care cannot be exercised in its use.
The strength of the solution as here reconi mended, one
part in one thousand, is the same as that used in sur-
gery, and is not such as to work injury unless taken into
the stomach. Great care should be taken in handling
the pure substance, and all treated potatoes should be
planted. The solution should not he placed in metallic
vessels. "

This method has been tried by Mr. T. B. Terry,
the well-known Ohio specialist, and endorsed. The
potatoes may be conveniently dipped in the solution if
they are first placed in coarse sacks, like coifee sacks,
through which the liquid readily passes. Mr. W. J.
Green, of the Ohio Experiment Station, has recently
announced that excellent results in scab prevention were
obtained by soaking the seed for one hour in dilute Bor-
deaux mixture.

Literature. — Dr. Eoland Thaxter's articles on tlie
subject are found in the reports of the Connecticut Ex-
periment Station for 1890 and 1891, and Professor Bol-
ley's contributions in Agricultural Science, Vol. IV, and
Bulletins Nos. 4 and 9 of the North Dakota Experiment
Station. Other articles may be found in the Cth, 7th
and 8th reports of the Massachusetts Experiment Station,
and in various other reports, bulletins and periodicals.

FUNGI AFFECTING THE SWEET POTATO

The BJack Rot

Ceratocystis fimbriata

There are several kinds of ^'rot" affecting the sweet
potato, which have been carefully studied by Dr. Byron
D. Halsted, of the Kew Jersey Experiment Station. To
liis studies we are indebted for much of the following
information upon the subject :

According to Messrs. Ilalsted and Fairchild, ^^the
most conspicuous sign of the present disease, and the
one w^hich distinguishes it from other diseases, occurs
upon the potatoes themselves. It consists in the j^res-
ence of dark, somewhat greenish spots, varying from a
quarter of an inch to four inches in diameter, sometimes
covering the greater part of the I'oot and extending some
distance into the tissue. Tliese sj)ots, wdien once seen,
can not be mistaken, as they are simply sunken areas
with distinct margins, like spots burned into the potato
with a metal die, which has left the skin uninjured.
Should the slightest doubt, as to the identity of the dis-
ease remain, after a superficial examination, the removal
of a small portion of the skin, exjoosing the olive-green
tissue below, would dispel it. Among the sprouts, or
young plants grown in hotbeds, the disease manifests
itself in dark lines upon the lower portion of the shoot;
and sometimes of the lower leaves, giving rise to the
name of '^ black shank" among the growers. These
dark lines or blotches often appear upon etiolated por-
tions of the stem, and are almost black in color. In
very severe cases the tip of the sprout wilts and dies.

172

THE BLACK ROT 1 73

No a23pearance in the field has so far been observed, that
would distinguish hills diseased with black rot from
those attacked by some other of the numerous rots ; but
the dark sunken areas on the potato, and the black dis-
colorations of the sprouts, can scarcely be confused with
any other sweet potato disease."

This black rot has been found seriously injurious in
New Jersey, Maryland, Delaware and Virginia, and it
])robably occurs in many other portions of the United
States. It frequently destroys twenty-five per cent, of
the crop, the injury taking place mostly after the pota-
toes are stored, when the fungus can easily pass from
root to root.

A microscopic examination of portions of diseased
roots shows the presence of threads of mycelium, which
push about between and through the cells, absorbing
the starchy matter with which the latter are normally
filled. These mycelial threads have thick walls, and are
olive-brown in color. Under suitable conditions of
warmth and moisture, they joroduce on the outside of
the skin of afi'ected root or stem numerous spores (called
conidia) of two distinct forms ; and there are also
formed within the substance of the potato certain flask-
shaped bodies, within which are produced a third kind
of spores. The disease is likely to start from affected
potatoes planted in hotbeds to obtain sprouts. The
mycelium may pass directly from the root to the young
sprout, or the latter may be inoculated by means of
spores. Such sprouts, when planted, produce diseased
roots.

Treatment. — The following preventive measures
are recommended by Messrs. Halsted and Fairchild :

1. The first and most important precaution to be
taken, in combating the disease, is to plant only per-
fectly healthy seed in the hotbed, even if it is necessary
to import such. This preventive measure is most essen-

174 FUXGI AXD FUXGICIDES

tial, as diseased seed will give diseased sprouts, which,
in turn, will grow a crop of worthless potatoes.

2. The selection of healthy sprouts is plainly nec-
essary, 'in case the fungus gets into the hotbeds, and
under no circumstances should diseased plants be put
into the field. The test of using copper fungicides in
the hotbed has not been made, but, from analosfv, seems
to promise assistance. If the fungicide is used the
shoots should be kept green with it until jiulled.

3. Fields which have become so impregnated by
the disease that they refuse to gi-ow ])rofitable crops, had
best be added to the regular farm rotation. This
method will, if continued for several years, allow the
accumulated infective material to burn itself out by con-
suminii all available food material in the soil.

4. Decaying roots and the refuse after digging
should be carefully removed from the field and burned,
as such debris adds to the food of the parasite.

5. The use of large quantities of barnyard manure
probably favors the development of the trouble, since it
adds greatly to the decaying vegetable matter of the soil.
Where the use of commercial fertilizers can be made to
take the place of manure, it will certainly be desirable
to make the chansfe.

6. Although no exjieriments have yet been com-
pleted upon the matter, it is probable the spread of the
disease in the bin may be checked by dipping the roots
in one of the cop2:)er mixtures, preferably the ammoni-
acal solution, before storing for the winter. What effect
tobacco smoke, or the fumes of sulphur, would have in
checking the disease in the bins remains to be ascertained.

Literature. — The two most important articles con-
cerning this disease that have come to the writer's notice
are. first, one by Dr. Halsted, published in 1890, in Bul-
letin TO of the New Jersey Experiment Station (pp.
7-14) ; and, second, one by Dr. Halsted and Mr. D. G.

THE BLACK ROT

175

Fairchild, consisting of an admirable resume of the
studies of these gentlemen, which appeared in 1891 in
the Journal of Mycology (v. VII, pp. 1-11). The reader
desiring information concerning the spores and spore
formation of the fungus should consult this article. A
discussion of the various other diseases of the sweet
potato will be found in Bulletin 76 of the New Jersey
Experiment Station.

FUNGI AFFECTING THE SPINACH

The Spinach Mildew

Peronospora effusa

Spinach, wlien forced for market under glass, is
subject to attack bv several fungous diseases, wliicli have

been investigated by Dr. B. D.
llalsted. The mildew is one of
the most destructive of these mal-
lidics. It is closely related to the
downy mildew of the potato, and
produces *'gray, slightly violet,
patches (i a velvety texture, upon
the under side of the leaves, while
from the upper side they liave a
pale yellow shade, due to the loss
of the green color.*' If a cross
section of the leaf be made through
one of these patches, and ii minute
jiiece placed under the microscope
on a glass slide, the fungus Vv-ill
be seen to have a structure similar
to Fig. 75, which represents on
the lower part the cells of the leaf
having the mycelium of the fun-
2:us runnins: between some of
them, sending here and there
''suckers" into the cells them-
selves to absorb their contents,
and pushing out through the

FIG 75. SPIJfACH IMIXBEW. , ,, . ^ ^ « +"Uo -Pvnifi'nrr

Section of leaf showiui^nivceii- brcathmg porc, tt, the truiting

Mag'JifieJr''"'''''"'''''^ ''"''"• stalk, i, which bears the spores, c.

At d one of the spores is shown, more magnified. These

spores are scattered to other plaiits, where they germinate

THE SPIXACH AT^^THRACNOSE

177

by sending out slender tubes, wliich may enter the leaves
through the breathing pores.

The Spinach Anthracnose

Colletotrichum spinacece

This is, perhaps, the most destructive of the spin-
ach diseases, as it grows rapidly, and, in consequence,
soon spreads over many plants. ^^The first indication
of its presence," writes Dr. Halsted, "is an indescriba-
ble moist appearance of the usually circular affected

part ; followed by the appearance
of minute brown pustules, while at
the same time a gray color develops
and the diseased area becomes dry.
The anthracnose is shown in Fig.
76, where an affected leaf, much
reduced in size, is seen, with some
portions killed by the fungus. No
particular part of the leaf is first
attacked, and, therefore, no two
leaves appeiir alike. In some cases
the largest leaves will be diseased,
in other plants only the younger
ones ; but sooner or later plants that
are affected will become entirelv
unfit for use. To test the rapidity
of the growth of the anthracnose,
healthy plants, grown in the labo-
ratory, were inoculated with the
spores, and in from five to seven days the spots sown
had become thoroughly diseased, and were bearing mul-
titudes of spores." Spinach is also subject to attack by
a leaf-blight, a white smnt and a black mold disease.

Treatment for Spinach Diseases. — As already
stated, the diseases discussed above affect most severely
12

FIG. 7G. SPINACH LEAF

AFFECTED BY AN-

THKACXOSE.

178 FCXGI AKD FUXGTCIDES

spinach forced under glass for early market. That
grown out of doors is not infested to nearly so great an
extent. As it is impracticable to treat the spinach
plants with the ordinary copper fungicides, except, pos-
sibly, when yery young, such cultural methods must be
adopted as will reduce the chances of infection to a
minimum. These methods include the collectins: and
burning of refuse leaves affected by any of the diseases,
and the changing of the location of the beds used for
spinach each year, if possible ; and if not, the changing
of the soil instead. Dr. Halsted suggests raking a mix-
ture of equal parts of air-slaked lime and sulphur into
the soil — a measure that is well worth trying. The flor-
ist paints his heating pipes with a sulphur mixture, to
keep the air of the greenhouse saturated with sulphur
fumes, in order to prevent mildew, and it seems 230ssible
that the air in hotbeds might also be more or less satu-
rated with such fumes to prevent fungous diseases.

Literature. — The only important general account
of these spinach diseases so far j^ublished in America is
to be found in Bulletin No. 70 of the Xew Jersey Exper-
iment Station. It is by Dr. B. D. Halsted, and to it
the present writer is indebted for the figures and infor-
mation given above.

FUNGI AFFECTING THE TOMATO

The Tomato Rot

Macrosporium tomato

The common tomato rot is often extremely destruc-
tive, both in field culture and under glass. It usually
first becomes noticeable when the fruit is about half
grown, appearing at the blossom end as a small blackish
spot, that increases in size as the tomato develops. The
tissues beneath the spot are destroyed by the fungus, so
that the fruit becomes flattened on top, and the inside
of the tomato is blackened. The fungus may finally
involve the whole fruit, producing a shrivelling and
blackening, that is only too familiar to most experienced
gardeners. An excellent account of this fungus, by Mr.
B. T. Galloway, may be found in the 1888 report of the
Tnited States Department of Agriculture (pp. 339-346.)

Treatment. — Professor L. H. Bailey, than whom
no American has more thoroughly studied the tomato,
says that this rot *'can be kept in check by spraying
with Bordeaux mixture or ammoniacal carbonate of cop-
per ; but it is difficult to apply the material to untrained
plants, especially upon rich soil, where they make a
thick growth. Plants which are trained to stakes and
pruned admit of thorough treatment. The rot appears
to be less, as a rule, if the plants are so trained that the
fruits and vines dry off quickly after rains and dews.
In single-stem training out of doors, rot was greatly
reduced this year. Straw placed underneath vines ap-
pears to increase the tendency to rot, and the same

179

180 FUXGI AXD FUXGICIBES

appears to be true of beaTv dressings of stable manure.
Tbe less improved varieties of tomatoes, like many of
tbe old angular sorts, and tbe cberrj and plum varieties,
are almost exempt from attack."

The Winter Blight

Professor Bailev bas described, under tbe name of
Winter Bligbt, a malady of greenbouse tomatoes tbat
sometimes proves disastrous to attempts to force tbis
fruit. It bas tbe general appearance of a bacterial
bligbt, altbougb no definite proof bas yet been made
tbat it is caused by bacteria. Wben first attacked tbe
leaves become dwarfed and somewhat faded, witb indis-
tinct yellowish spots on the surface. ''The spots grow
larger, until they often become an eighth of an inch
across, or even more, and they are finally more or less
translucent. This injury to tbe foliage causes tbe j^lants
to dwindle, and tbe stems become small and bard.
Fruit production is lessened, or if tbe disease apjoears
before tbe flowers are formed, no fruit whatever mav
set. In two or three instances in wbich young plants
were attacked, tbe disease killed tbe plant outrigbt ; but
a diseased plant ordinarily lives throughout tbe winter,
a constant disappointment to its owner, but always
inspiring the vain hope tbat greater age or better care
may overcome tbe difficulty." This bligbt has not been
observed to attack the fruit. As stated above, it appears
to be due to bacteria — a species of micrococcus — but is
different from tbe tomato bligbt of tbe Southern States.
Various remedies have been tried witbout success, and
the best 2:)reventive measures are those of the immediate
destruction of all blighted plants, and tbe use of new
soil in tbe greenhouse each fall.

The Bacterial Tomato Blight

Tomatoes in tbe Southern States are commonlv
affected by a bligbt similar to, if not identical witb, the

THE BACTERIAL TOMATO BLIGHT 181

bacterial blight of potatoes. The tissues of diseased
plants teem with bacterial germs, and no other form of
fungus is present at first. The malady has been studied
by Dr. B. D. Halsted, who has published a preliminary
account of it in Bulletin No. 19 of the Mississippi Ex-
periment Station. The presence of the disease is usu-
ally shown by the wilting of the younger leaves, especially
those at the ends of the stems, and the yellowing of the
older foliage. The stems themselves also become af-
fected, and when closely examined, are seen to have
numerous watery spots. A longitudinal section of such

FIG. 77. r.LIOHTED TOMATO LEAVES.

a stalk reveals a greenish, watery center, very different
from that of the healthy plant.

There is a blight affecting squashes and melons that
seems to be the same disease as this, and also as the
potato blight already referred to. Consequently neither
of these crops should follow the other on the same land, in
case the disease has appeared. It is believed that the
soil becomes so contaminated with the germs that, in
case either of these crops follows the other, the injury
may appear again. In addition to proper rotations, the
burning of all diseased plants and rubbish in the field,
and spraying early with Bordeaux mixture, are recom-
mended as remedial measures.

FUNGI AFFECTING SEEDLINGS AND

CUTTINGS

The Damping=off Fungus

Pytliium DeBaryanum

The malady known as '^ dam ping-off " is familiar to
all experienced gardeners. It affects the seedlings and
cuttings of a great yariety of plants in the ^propagating
bed. It appears often est when the soil surface is damp,
the temperature high and the sky clouded. ^'Its first
appearance is indicated by a slight j^aleness and droop-
ing of the seedlings. If these be carefully removed,
it will be seen that the root, either throughout its length,
or in portions, is beginning to shrink aud decay, and
that the root hairs are destroyed. Later, if the plant is
not vigorous enough to resist tne fungus and to put
forth secondary roots, the disorganization of the tissue
extends to the stem, resulting nltimately in the toppling
over of the plant and its thorough decay, although, in
some instances, the plant remains green for some days
after falling. This extends from one plant to another,
until only a few or none of the seedlings in a bed may
be left."* The plants attacked and the soil between
them becomes more or less covered with the mildew-like
growth of the fungus mycelium. Recent investigations
indicate that the fungus gains entrance to the plants
throusfh the roots.

Treatment. — According to Mr. T. W. Gallo^vay,
of Harvard University, the fungus may be destroyed by

*T. W. GaUoway.

182

THE DAMPING-OFF FUNGUS 183

giving the soil the conditions (heat and moisture) favor-
able to the germination of the spores, and then, a few
days later, exposing it thoroughly to a very dry, hot
atmosphere, so as to kill the delicate growth of the fun-
gus. It seems likely that the trouble might be avoided
by watering the plants wdth an extremely dilute solution
of copper sul2:)hate — say a pound to two hundred gallons.
The preventive measures recommended by gardeners,
are the avoidance of a high temperature and moist at-
mosphere, keeping jilants stocky, giving plenty of air,
and changing the soil frequently.

Literature. — A discussion concerning damping oS
may be found in the American Garden for June, 1890
(XI, 347-350) ; also in H. Marshall Ward's Diseases of
Plants; and in the Transactions of the Massachusetts
Horticultural Society for 1891. The latter contains the
article by Mr. Galloway from which the above quotations
were made.

:p.a.i^t "v

Fungi Affecting Cereal and
Forage Crops

^

PLATE XVII. OATS SMUT.

FUNGI AFFECTING OATS

The Loose Smut

Ustilago avence

Some estimates of the loss due to this fungus have
already been given in the Introduction (p. 2). A good
representation of its appearance is seen in Plate XVII.
The black masses consist of millions of minute spores,
by means of wliich the fungus reproduces itself. The
spore masses ripen about tlie time tlie oats are in bloom,
when the cliaif enveloping the embryo seed is spread
wide open. The spores are blown over the field, and
many of them lodge on the inner side of the chaff parti-
cles, where they remain as the seed ripens, and are not
dislodged when it goes through the threshing machine.
The smut spores are also largely distributed from the
smutted heads and lodged in the chaff of sound kernels
during threshing, although it i.s probable that only a
small percentage of them get far enough into the chaff
to infect the plants that develop from the kernels.

After the spores have lodged in the chaff they re-
main there until the oats are planted. Then they ger-
minate by sending out little tubes, which enter the
young plant through the first leaf-sheath. These tubes
are only able to gain access to the plants during a very
short period of the growth of the latter. After the oats
have pushed out the second leaf the danger of infection
by smut is past. When the germinating tube has entered
the plant it sends out branches in all directions, pene-
trating the stem and all its parts, thus forming the

187

188

PUKGI AND FUlfGICIDES

mycelium, or vegetative portion of the fungus. As the
oats plant grows this mycelium also develops, taking
possession of all the new tissues of the host, and form-
ing within the head a mass of thick threads. These
threads eventually produce vast numbers of spores, so
using themselves up in the operation that they become
gelatinous, and finally altogether disappear, leaving

g

FIG. 78. SMUT SPORES GEllMIXATIKG. MAGNIFIED.

nothing but the jjowdery mass of spores, which are
blown about to infect other plants, and thus begin anew
the cycle of existence.

The smut mycelium usually produces no peculiar
effect upon its host-plant early in the season. Infested
plants are seldom distinguishable from healthy ones

THE LOOSE SMUT 189

until it is nearly time for the oats to blossom. Then
comes a sudden change; the spores develop rapidly, and
are dry, powdery masses before the plants are through
blooming. When one of the branches of a stooling
plant is infested, the others from the same root usually
are also, a result of the entrance of the smut so soon
after the seed germinates. It sometimes happens that
only a part of the spikelets of a head are attacked, and,
according to Kellerman and Swingle, ^^in a few cases
smutted heads have been collected where the smut has
destroyed the grain and flowering glumes, while the
large outer husks are yet entirely sound. Such a head
would scarcely be seen to be smutted unless carefull}^
examined." Most of the best authorities agree that
there is very little danger of infecting oats with smut
from the spores in barnyard manure applied to the soil.
The mycelium of the oat smut fungus is composed
of extremely delicate threads, and the sj^ores are very
minute, ranging from one-five thousandth to one-three
thousandth of an inch in diameter. They arc oval, or
sub-globose in shape, with the outside wall spiny, or
warty, having minute elevations all over its surface.
One side is lighter colored than the otlier. In water or
in a nutrient solution these spores germinate readily, as
seen in Fig. 78, the germinating tube appearing on the
light side of the spore. As these tubes grow, cross par-
titions (c, d, e, f,) frequently appear, and sometimes the
peculiar little cells called sporidia are developed [a).
These sporidia might be called temporary spores, because
if placed in a nutrient solution, or manure water, they
grow something as spores do. Some authors have
claimed that on account of their presence in manure
applied to the land, oats may be infected with smut, but
this is disputed by Jensen and others. When massed
together the spores are of a dark, dusky brown color,
but when separated and viewed with the microscope

190

FU:S'GI AXD FUNGICIDES

FIO. 70. OATS GER-
MI>'ATING.

they are clearer and lighter, though still brown. Pro-
fessor Kellerman estimates that a compact cubic inch of
?mnt would contain 64,000,000,000 spores.

Treatment. — In 1887, Professor J. L. Jensen, of
Denmark, announced that the smut of oats and wheat
can be prevented by soaking the seed for five or ten min-
utes in water heated to 133° F., with-
out injury to the germinating quali-
ties of the seed. Further experiments
in Europe by the same investigator,
and in America by several experi-
menters — notably Kellerman and
Swingle in Kansas, and Arthur in
Indiana — have abundantly justified
these claims, and have demonstrated
that by this simple treatment agricul-
turists can prevent, practically, all of
the loss now suffered from this dis-
ease. And, strangely enough, these exj)eriments have
shown that the treatment indicated not only prevents
the smut, but that it also hastens the germination of the
seed and increases the yield, above that whicli the pre-
vention of the smut accounts for, to such an extent that
it would pay to treat it were no smut present. The
hastening of germination has been well represented by
Professor Arthur,' in Fig. 79, showing oats that have
been in a germinator three days ; a, having been previ-
ously soaked in a solution of copper sulphate ; h, having
had no treatment; and c, having been soaked in hot
water. It will at once be seen that the hot water has
hastened the germination, and that the cop2:>er sulpliate
has retarded it. In Fig. 80 are represented the same
kernels after they had been growing two weeks on moist
blotting paper; d is the one treated with copper sul-
phate ; e the one untreated ; and / the one soaked in
hot water. As will be noticed in the engraving, the

THS LOOSE SMUT

101

relative growth of the three plants is practically the
same as it was after the seeds were three days in the
germinator.

In Kansas Professor Kellerman made a special series
of experiments, which showed that there was an increase

FIG. 80. OATS PLANTS TWO "WEEKS OLD. ONE-HALF NATUKAL SIZE.

of from four to eio-ht bushels per acre over that ac-
counted for by the mere prevention of the smut, when
the seed was treated with hot water.

Professor Arthur has shown that the oats may be
treated with hot water long before the time of planting,
with as good results, both as to prevention of smut and
increase in yield, as when treated just before planting.

192 FCifG] AKD FUXGICIDES

•

Tlie following method of treatment with hot water
has been recommended, as adapted to the facilities of
most farmers. Have ready for the work some coffee
sacks, two ordinary wash-tubs, a good snpply of hot
water and a clean barn floor. Partially fill tub No. 1
witli water heated to about 130° F., and tub Xo. 2 with
water at 140° F. Then fill the cofl!ee sacks with the
oats to be treated, and, taking one sack at a time, im-
merse it a minute or two in tub No. 1, for the jmrpose
of partially heating the oats ; then lift it up, let it drain
for a moment, and then dip it in tub No. 2, leaving it
there for from five to eisrht minutes, turnin"; and knead-
ing the sack to get all the seed soaked. Then empty
the oats on an airy floor — if possible, in the sunshine or
a draft of wind, and on a dry day — and let them become
thoroughly dry. A su^^ply of hot water should be kept
on hand, some of which is to be poured into the tubs at
frequent intervals to replenish the supply and keep up
the temperature, which must be determined often by a
good thermometer. In tub No. 2 the water should
never get above 145°, nor below 133°

For a long time solutions of copper sulphate have
been used to prevent grain smut, but in the light of our
better knowledge they should be discarded. They retard
the germination of the seed and decrease the yield.

Experiments at the Kansas Station, by Professor
Kellerman, show that oat smut may also be prevented
by soaking the seed for twelve hours in a solution of one
pound of potassium sulphide (liver of sulphur) to ten
gallons of water. '^ Place the seed in a wooden vessel,
and pour on the solution until the seed is covered several
inches deep. Stir the solution before pouring on the
grain, and thoroughly mix the seed several times before
taking the latter out of the solution. Then

spread out to dry. It will probably be best to sow the
seed as soon as possible, and before it becomes thor-

THE OATS EUST 193

ougbly dry." The hot water treatment, however, is
probably the better one.

Literature. — An account of Professor Jensen's
experiments may be found in the Jouroal of the Eoyal
Agricultural Society of England (v. 24, part II, 1888).
The following publications also contain accounts of this
disease : Kansas Experiment Station, Bulletins 15, 22 ;
rei^ort for ]889, ]3p. 213-288; Indiana Experiment Sta-
tion, Bulletin 35 ; North Dakota Experiment Station,
Bulletin No. 1 ; United States Department of Agricul-
ture, Farmer's Bulletin No. 5.

The Oats Rust

The rust of oats is essentially the same as that of
wheat, being caused by the same fungi, and the account
given on Pages 200-201 will suffice for this.

15

FUNGI AFFECTING WHEAT

The Bunt or 5tinkin:g Smut

Tilletia foeteiis

This is the most destructive smut affecting wheat.
It differs from the loose smuts in that the indiyidual
kernels are affected, instead of the whole head. Accord-
ing to Professor Arthur, wheat j^lants injured by this dis-
ease *^ thrive about as usual, the head fills and the chaff
is distended, as if with normally plump grain. A close
observer will notice, however, that already before wheat
heads out the diseased plants have a darker green color
and somewhat more luxuriant appearance. When the
grain is only six inches high or so, this difference in
appearance is quite striking, the affected plants being
darker green and taller, as if droppings of manure had
forced them to extra growth. The growth does not con-
tinue so long, however, as in the healthy plants, so that
they do not usually become so tall, and are premature in
heading and ripening up the leaves. The characteristics
now become rather more evident. The affected heads
retain a bluish-green, or greenish- lead color, for some
time after tlie sound ones begin to ripen, and then take
on a bleached appearance, in strong contrast to the yel-
low of the sound heads ; the heads being much lighter
stand more erect, and the chaff and beard are more ojoen
and spreading (Fig. 81)." If the injured kernels are
broken open they are found to contain a solid mass of
black powder — the spores of the fungus.

The life-historv of this funsrus does not differ essen-
tially from that of the loose smut of oats already dis-
cussed (pp. 187-193).

194

THE BUNT OR STIN'KING SMUT

195

Treatment. — This smut may be prevented by the
hot water treatment mentioned in connection with oat
smut. Mr. W. T. Swingle gives the following directions
for treating seed wheat :

*^ Provide two large vessels — as two kettles over a
fire, or boilers on a cook stove — the first containing warm

S^

\

\^

FIG. 81. WHEAT BUNT.

water (say 110° to 130°) and second containing scalding
water (132i°).

^'The first is for the purpose of warming the seed,
preparatory to dipping it into the second. Unless this
precaution is taken, it will be difficult to keep the water
in the second vessel at a proper temperature.

196 FUXGI Ai^D FUI^GICIDES

'^The seed which is to be treated must be placed, a
half bushel or more at a time, in a closed vessel, that
will allow free entrance and exit of water on all sides.
For this purpose a bushel basket made of heavy wire
could be used, with which spread wire netting, say
twelve meshes to the inch, or an iron frame could be
made at a trifling cost, over which the wire netting could
be stretched. This would allow the water to pass freely,
and yet prevent the joassage of the seed. A sack made
of loosely woven material (as gunny sack) could, perhaps,
be used instead of the wire basket. A perforated tin
vessel is, in some respects, preferable to any of the above.

'^Now dip the basket of seed in the first vessel;
after a moment lift it ; and, when the water has for the
most part escaped, plunge it into the water again, repeat-
ing the operation several times. The object of the lift-
ing and plunging, to which should be added also a rotary
motion, is to bring every grain in contact with the hot
water. Less than a minute is required for this prepara-
tory treatment, after which plunge the basket of seed
into the second vessel. If the thermometer indicates
that the temperature of the water is falling, pour in hot
water until it is elevated to 132-^°. If it should rise
higher than 135°, add small quantities of cold water.
This will doubtless be the most simple method of keep-
ing the proper temperature, and requires only the addi-
tion of tw^o small vessels, one for cold and one for boil-
ing water.

^^ Steam, conducted into the second vessel by a pij^e
provided with a stopcock, answers even better, both for
heating the water and elevating the temj^erature from
time to time.

^'The basket of seed should, very shortly after its
immersion, be lifted, and then plunged and agitated in
the manner described above ; and the ojoeration should
be rupeated eight or ten times during the immersion,

THE BUNT, OR STINKING SMUT 197

which should be continued fifteen minutes. In this way
every portion of the seed will be subjected to the action
of the scalding water. Immediately after its removal
dash cold water over it or plunge it into a vessel of cold
water, and then spread out to dry. Another portion can
be treated similarly, and so on until all the seed has been
disinfected. Before thoroughly dry the seed can be sown ;
but it may be thoroughly dried and stored if desired.

^^The important precautions to be taken arc as fol-
lows : (1) Maintain the proper temperature of the
water (1321° F.), in no case allowing it to rise higher
than 135°, or to fall below 130°. This will not be diffi-
cult to do if a reliable thermometer is used, and hot or
cold water be di]3ped into the vessel as the falling or ris-
ing temperature demands. Immersion fifteen minutes
will not then injure the seed. (2) See that the volume
of scalding Avater is much greater (at least six or eight
times) than that of the seed treated at any one time.
(3) Never fill the basket or sack containing the seed
entirely full, but always leave room for the grain to move
about freely. (4) Leave the seed in the second vessel of
water fifteen minutes."

Literature. — This smut has been very often treated
of during recent years. Articles concerning it may be
found as follows : Bulletin No. 1, North Dakota Exper-
iment Station ; Bulletin No. 28, Indiana Experiment
Station ; Bulletins and reports Kansas Experiment
Station, 1890-1891.

198

FUXGI AND FUNGICIDES

The Loose Smut

Ustilago tritici

The loose smut of wheat is at once distinguished
from the bunt by the fact that the spores are not con-
cealed, so that usually the kernels
resemble masses of black powder.
Such a head is represented at Fig, 81,
a, eno^raved after Kellerman and Swin-
gle. The powder soon blows away,
leaving the bare chaff and stem, b.
This disease is found, to a greater or
less extent, wherever wheat is grown,
but is seldom as destructive as the
bunt. No successful method of com-
bating it has yet been found. A good
discussion of it occurs in the second
raport of the Kansas Experiment Sta-
tion, 1889, pp. 261-268.

It was formerly supposed that the
loose smut of oats was the same as that
of wheat ; but recent observations indi-
cate that the fungi causing the two
maladies are different species, and that
they cannot pass from one ^olant to the
other. Professor Bessey has shown
that part of the heads of given stools
of wheat may be affected with loose
smut, and part be healthy.

The Wheat Scab

Fusisporium culmorum

This is a peculiar disease which attacks the heads
and kernels of wheat. It is usually first noticed just as
the heads are beginning to turn, when an examination of
infested fields shows that with a portion of the heads the

WHEAT SMUT.

THE WHEAT SCAB

199

upper or lower half has prematurely whitened, leaving
the rest green, the whitened part having on many of the
glumes a more or less distinct pink or orange covering
of the mycelium and spores of the fungus. Under a
high power of the microscope this
fungus is seen to be composed of long
curved spores, as shown in Fig. 82.
According to the botanists, it is a
species of Fusisporium. The kernels
attacked by the fungus become mere
shells, covered inside and out with
mycelium (Fig. 83) and in passing
through the thresher they are blown
away with the chaff. The yield is
sometimes greatly decreased. In
1890 I saw a field of one hundred
acres in Madison County, Ohio, con-
sidered the finest wheat field in the
county, which was expected, shortly before harvest, to
yield thirty-five to forty bushels per acre, so severely
attacked by the disease that the yield was reduced to

eight bushels per acre.
Two other fields, one of
twenty-five and the other of
fifty acres, were shrunken
in yield at least one-third,
from the same cause. The
fungus apparently gains
access to the tender, unde-
veloped kernel, sapping its
life and sending down feed-

FIG. 82.
SPORES OF WHEAT
SCAB. MAGNIFIED.

FIG. 83.

WHEAT KERNELS AFFECT-
ED BY SCAB.

ers into the main axis of
the head on which the kernel and inclosing chaff are
borne. The functions of this part of the plant soon
become locally deranged, and, in consequence, the sup-
ply of nutriment for the portion of the head above the

200 FUJfGI AND FUNGICIDES

affected part is cut off, causing it to stop growing and
lose its green color. As the fungus develops it j^roduces
great numbers of spores, which give the pinkish color to
the affected ^larts. As a rule, the disease is worse on
WTak-growing varieties, and those fields which are sowed
latest. Consequently, vigorous growth and early blos-
soming are thought to be the chief safeguards against
the maladv.

The Wheat Rust

Puccinia ruhigo-vera

Probably no disease of cereals causes a greater loss
to American farmers than the rust of wheat. It appears
to be known wherever wheat is grown, and is often
responsible for the destruction of a large percentage of
the crop. It has, until recently, been quite generally
assumed, by botanists and others, that the fungus caus-
ing wheat rust in America is the same species that
causes it in Europe — a species known to science as Puc-
cinia graminis — but it has lately been shown that our
common rust is often an entirely different fungus, w^hose
Latin name appears above. The European sjoecies passes
one stage of its existence upon the barberry, causing the
familiar cluster-cups, but the other fungus has no con-
nection with the barberry. It has a first, or cluster-cup
stage, which is passed on certain plants belonging to the
Borage family ; and has also two different stages upon
wheat. The first of the wheat stages — but the second
in the life-cycle of the fungus — is the red rust stage,
called, bv botanists, the uredo staire. It is in this con-
dition that the fungus is most destructive. Later in
the season an entirely different kind of spore is produced
— the so-called teleuto-spore — which forms the third
stage of the fungus. But recent investigations have
shown that the second, or uredo- stage, is able to survive

THE WHEAT RUST 201

the winter and reproduce itself indefinitely, so that it is
probable that, in many cases, this stage of the fungus is
all that is necessary to explain its continued existence.
All farmers know with what marvelous rapidity
wheat rust spreads, if wet weather occurs shortly before
harvest. It is a disease for which, as yet, no successful
remedy has been found. Full knowledge of its life-his-
tory is yet wanting, and, possibly, when more is known,
successful preventiyes may be suggested. Early ripen-
ing varieties are less liable to damage than others. The
fungus often passes the summer on volunteer wheat,
hence this should be destroyed. A discussion of the
life-history of the European wheat rust may be found in
\i. G. Smith's ^'Diseases of Field and Garden Crops"
(pp. 147-20?). The American rust is treated of in Bul-
letin No. 26, Indiana Experiment Station ; Bulletin No.
5, Minnesota Experiment Station ; and in various other
periodicals.

FUNGI AFFECTING INDIAN CORN

The Corn Smut

Ustilago zece-mays

The smut of Indian corn is one of the most widely
distributed and generally known of the fungous diseases
of i^lants. It jn-obably occurs wherever this crojo is
extensiTely grown, and it has been known for many
years. The amount of injury it does varies greatl}^ but
has seldom been accurately determined. In the report
of the Tenth Census of the United States, Professor
Brewer writes that he has heard of instances in which
the damage was estimated as high as sixteen per cent.,
although he had, himself, never seen a field which was
injured to the extent of one per cent. Professor Bessey
reports that in a garden patch where sweet corn had
been grown for several successive years, sixty-six per
cent, of the crop was destroyed by smut one season.
The general average, the country over, however, prob-
ably does not exceed one or two per cent.

Although corn smut usually infests the ears of the
plant, it is occasionally found upon tassel, stem and
leaves. On the ear it first appears as a white, malformed
mass, representing either the whole ear or a portion of
the kernels (Fig. 84). The whiteness gradually becomes
darker, finally changing into a brownish-black powdery
mass, consisting of millions of the minute spores or
reproductive bodies of the fungus. On the tassels the
swellings are not so large, and on the stem and leaf
their size varies greatly.

202

THE CORX SMUT

203

When one of these spores comes in contact with a
drop of water it soon germinates by sending ont a little
tube, which has the power of developiog certain second-
ary spores, called sporidia. The sporidia themselves,
have the power of germinating, under favorable condi-
tions, and in a liquid containing sufficient organic mat-

FIG. 84. I'AKT OF SMUTTKI) EAR OF COJJN,

ter for their nourishment (manure water, for example),
they can continue growing and multiplying for an indef-
inite period. It is believed, by some authors, that these
sporidia may develop in the barnyard, from the spores
which find their way to the manure pile, and be carried

204

FUNGI AXD FUXGICIDES

to the field with the manure, finally infecting the plants,
but this has not yet been definitely determined. The
observations of Kuhn indicate that the germinating
.mycelium penetrates the very young corn plant at the
root node and the first formed joint, and that after the
corn gets well started the danger of infection by smut is
passed. It has generally been supposed that the spores
adhered to the seed, and caused infection ; bnt recent
experiments at the Kansas Experiment Station — in
'-'hich corn kernels were rolled in smut spores, without

increasing the amount of
smut in the resulting crop —
throw so much doubt upon
tills assumption tliat Pro-
fessor Kellerman thinks that

'^further
necessarv in order

investigation

IS

to deter-
mine the mode of infection,''
adding that this is *' a point
that must be settled before

FIG. 85. SMUT SPORES GEB.nxAT- ^^ ^au hopB to cmploy ra-
iNG AND FORMING spoRiDiA. tioual mcthods for the pre-
vention of tills annoying and destructive pest."

It seems pretty well proven, however, that the smut
can exist in the soil from year to vear, and infect sue-
ceeding crops. The following experience, related by
Professor Bessey, as occurring in Iowa a few years ago,

shows this

a

One season a i^iece of land, including

about three-fourths of an acre, was planted with sweet
corn for table use. Some smut made its appearance the
first year, but it was all allowed to fall back to the
ground. Kone of the stalks were removed, but all were
plowed under, and the second season the ground was
again planted with sweet corn, for table use as before.
This time the smut was remarkably abundant, but again
it was all allowed to fall upon the ground, and was

THE CORN SMUT 205

plowed under with the stalks. The third season the
ground was planted as before, and this time fully two-
thirds of the ears were affected with smut. In fact, the
smut was so abundant that but little corn was gathered,
and the crop was practically abandoned. The ground
was found to be now so filled with smut as to unfit it
for further use for corn, and it was consequently assigned
to other uses. The lesson is very obvious. Smut left
on the ground will produce smut the next year."

After the mycelium of the smut fungus has pene-
trated the corn plant it grows along with the latter,
pushing its way through the tissues of the stem, and
finally develoj^ing extensively, by means of many
branches, in the ear or tassel. From this mass of
branches the spores develop, the latter absorbing so
much of the substance of the former that the mass of
mycelium becomes gelatinous, and finally disappears,
leaving in its place the familiar blackish, powdery mass
of spores. Up to the time of maturity the smut mass is
surrounded by a dull white membrane, which finally
bursts and allows the spores to escape.

Many farmers believe that corn smut is very injuri-
ous to cattle when eaten by them. Cases of death at-
tributed to this cause are not uncommon ; but feeding
experiments made by Professors Gamgee, Henry, and
others, indicate that the amount of smut cattle are likely
to eat, under ordinary circumstances, Avould do little, if
any, injury. The only plant besides Indian corn upon
which this kind of smut is known to develop, is a coarse
grass called Teosinte, which is sometimes used as a for-
age plant in the Southern States.

Microscopic Characters. — The spores of corn
smut are so minute that it has been estimated that from
30,000 to 50,000 of them will adhere to the moistened
head of a common pin ; that 25,000 of them, laid side
by side in a straight line, would measure an inch ; and

206 FUXGI AXD FUXGICIDES

that single cubic inch of smut would contain more
than 15,000,000,000 of them. The dry spores are glo-
bose, and brownish-black, with the outer surface thickly
studded with elevated points. The metliod of germina-
tion and of the formation of sporidia is well ilkistrated
at Fig. 85. The mjTelium is whitish, and the tips of
the threads are able to penetrate the cells of the corn
plant. The cells are also peiietrated by the haustoria,
or suckers from along the mycelial threads.

Treatment. — In the liglit of our present knowl-
edge, measures looking toward the lessening of loss from
smut must be largely of a preventive nature. As Pro-
fessor Kellerman has pointed out, we must know the
mode of infection of the corn plant by smut before we
can be sure of the most rational remedy. The fact,
however, that smut thrown or left upon the ground pro-
duces the disease in succeeding crops, and the apparent
probability that infection may be brought about by the
distribution of the spores, or sporidia, in manure, indi-
cate (1) that rotation of crops should be practiced, and
(2) that as much of the smut as possible should be
destroyed before it comes to maturity. It will pay the
careful farmer to cut out and burn, or bury, the smut
balls before the membrane covering them bursts and
allows the spores to escape. At the time of husking, all
smut masses that have escaped detection should also be
disposed of. "AVhere domestic animals are allowed to
eat smut in the field they become the carriers of the
spores, and their droppings, filled with the still living
spores, become the centers of infection. Xo animal
should be permitted to eat smutted corn, even though
the owner be convinced of its harmlessness to the animal
itself. The harm lies in the distribution of the spores,
which are little, if at all injured, by passing through the
alimentary canals of animals.*' (Bessey.)

The soaking of seed corn in copper sulphate solu-
tions to destroy the adhering smut spores, has frequently

THE IKDIAN" CORN RUST 207

been recommended, but the failure of Professor Keller-
man's experiments, in attempting to increase the amount
of smut by rolling the seed in the spores, indicates that
this is hardly worth while, especially as the copper sul-
phate soaking has the effect of diminishing the vitality
of the seed. If treatment of this kind were desirable, it
would be better to adopt the hot water method used to
destroy the smut of oats and wheat. From the fact that
the smut enters the plant when very young, we should
hardly expect that spraying the growing corn with the
Bordeaux mixture, or other fungicides, would do any
good ; and recent experiments confirm this supposition.
Literature. — An excellent general account of corn
smut, by Professor A. B. Seymour, may be found in
the 1887 report of the Department of Agriculture
(pp. 380-389).

The Indian Corn Rust

Puccinia maydis

The disease of Indian corn known as rust has at"
tracted comparatively little attention from American
farmers, and, so far as its injuries are concerned, it is,
indeed, of minor importance. It is fortunate that this
is the case, for, as yet, no successful method of combat-
ing it has been suggested.

Corn rust is quite similar, in character and appear-
ance, to the familiar red rust of wheat and oats. It
usually appears about midsummer, in the shape of small,
brownish, dust-like blotches on the surface of the corn
leaf. These dust-like patches, or pustules, consist of
the summer spores of the fungus ; the spores are of a
rich yellowish brown color, and are easily blown away by
the wind. Toward the end of summer these brownish
spores are replaced by blackish ones, so that the pustules
'then assume a blackish appearance. These dark-colored

208

FUN'GI AlfD FUXGICIDES

spores are the winter sjDores, and are very different in
structure and appearance from the summer spores. The
two kinds are produced from the same mycehum, and at
certain seasons they may be found intermingled in the
same mass, or pustule. This fungus usually only devel-
opes after the corn has gotten well along in its growth,
so that the effect of its injury is less than if the very

FIG. 86. CORN KUSt.

a, Section of leaf showing teleuto-spores ; h, uredo-spores; c, teleuto-spores.

Magnified.

young plants were attacked. Hence it seldom assumes
a serious economic importance.

The brown summer spores (called by botanists uiedo-
spores) are nearly spherical, with the outer wall thickly
studded with minute pointed projections (Fig. 86 l).
They are about one-one thousandth of an inch in diam-
eter, and are borne on slender stalks arising from the

THE BACTERIAL DISEASE OF CORX 209

mass of the mycelium, from which they readily separate.
They serve to spread the disease during a limited time
in summer, but ai-e supposed not to survive the winter.
The blackish winter spores (called by botanists the
teleuto-spores) are decidedly diiferent in structure and
appearance from the others. A cross section of a corn
leaf through one of the blackish pustules is represented
at ft, Fig. 86. As will be seen, the spores are borne on
stout stalks, to which they remain attached, c. The
spores themselves are so divided by a partition across the
middle that they are practically double ; each part can
germinate independently of the other. These spores
survive the winter.

Treatment. — As already intimated, no practical
remedy is know^n for this disease ; and, fortunately,
none as yet is seriously needed. A more extended dis-
cussion of this malady is published in the 1887 report of
the Department of Agriculture (pp. 389-391).

The Bacterial Disease of Corn

In 1889 Professor T. J. Burr ill, of the University
of Illinois, announced the discovery of a peculiar malady
of Indian corn, Avhich he had proven was due to the
presence of bacteria. The disease was then prevalent
over a considerable area in Illinois, and investigations
since have indicated that it does much damage — often
not understood, or else attributed to other causes — over
a large portion of the corn-growing region of the West.
As the disease is an obscure one, not easily recognized or
described. Professor BurrilFs account of its appearance
is quoted below at length.

External Manifestations. — "The first indication
of this disease in a field of corn, as noticed in ordinary
observation, is the dwarfed condition of the young
plants. This commonly occurs in spots of various sizes,
from a few square rods, to an acre or more, and often,
14

210 FUNGI A^'^D FUNGICIDES

though by no means always, on soil of a character some-
what different from the rest of the field. It seems hard
to designate what special condition or quality of soil is
most usually associated with the disease; but, upon the
whole, it is found in the rich spots, rather than in those
of the poorer quality. In many cases it is upon the
lowest ground, whether or not water has temporarily
stood in the hollows. The most definitely bounded area
noticed was upon a spot which had, until the year previ-
ous, been too wet for tillage, but Avhich had been tile
drained and broken up, the sod having rotted.
But ordinarily there are no such definite borders to the
infected areas, and often nothing whatever to suggest a
reason for their peculiar distribution.

'^Upon closer observation it is found that young
diseased plants, besides being smaller than the healthy
ones, are uniformly yellowish in color, the lowest leaves
showing worst. As death overtakes these leaves, they
apparently succumb by a general decline from the
healthy state, and rarely die, and wither chiefly at the
ends and margins as in some other cases. When some
of the affected 2:)lants are pulled from rhe ground they
are found to give way too easily, in consequence of the
death, to a greater or less extent, of the oldest and low-
est roots. In anything like severe cases at least one-half
the roots — always the lowest — are injured, and usually
dead. The bottom portion of the stalk is likewise
affected, and will be found dead or dying. If split lon-
gitudinally through the middle, the inner tissue of this
lower part is seen to have a uniform dark color ; and a
similar discoloration, gradually becoming less and less
pronounced, appears in the next succeeding nodes, or
joints, while the spaces between them (internodes) are
seemingly healthy. On the surface, when carefully
freed from dirt, brownish, corroded spots can be found,
sometimes strictly bordered, again diffusely spreading.

THE BACTEKIAL DISEASE OF CORN 211

Sometimes masses of semi-transparent, rather firm, gel-
atinous material are found upon these external corrosions.

"After midsummer, especially, the disease becomes
apparent through discol orations of the portions of the
leaves called the sheaths, which closelv invest the stalk.
Thjse leaf-sheaths become variously spotted, as observed
from the exterior. Sometimes the watery-brown por-
tions are mere specks ; sometimes large irregular patches,
and of all grades between these extremes. The discol-
orations become brown, of a half-rotten appearance.
Occasionally there is a little reddish color, more often
bordering the brown. If, now, these aifected leaves are
stripped from the stalk, it will be found that tlie evi-
dence of injury is much more conspicuous on their inner
side. The injured patches are larger, have a more
watery appearance, and sometimes are more or less
smeared with the same gelatinous substance previously
mentioned as occurring on the diseased stem below the
ground ; but here on the leaf -sheaths it is usually spread
in a thinner coating, or layer, instead of in round masses.
This infection of the leaf-sheaths evidently comes later
in the season than the first noticed form of the disease
on the roots. It seems also to be evenly distributed
through the field, and to occur upon large as well as
small plants.

"Finally, the ears are, at least occasionally, aifected.
Externally, the appearance of the outer husks is like
that of the diseased leaf-sheaths. Internally, in tlie
worst stage, the whole ear — husks, which should be still
green, young cob and kernels, and the mass of "silks"
— is reduced to a moist state of corruption, though not
ill-scented. The parts lose their normal rigid, or turgid
quality, appear as if wilted, and are packed closely
together, if not actually adhering by the gummy exuda-
tion from the tissues. Very often these ears subse-
quently become moldy, penetrated through and through

212

FUi^Gl AND FUXGICIDES

by a close, very white, felt-like fungus. Possibly this
fungus sometimes makes its inroads into the ear without
the bacteria as forerunners ; but from present knowledge
it seems probable that it is a secondary intruder. These
moldy ears are, in certain seasons, very numerous, and
are readily recognized by the liusker, as well as by the
buyer, Avhen the loads are sent to market."

Microscopic Characters. — When placed under a
very high power of the microscope, the juices from
affected portions of corn plants are seen to be swarming
with minute bacteria. These bacteria, when magnified

FIG. 87. BACTERIA OF CORN DISEASE.

nearly three thousand times, resemble Fig. 87. Each
individual measures less than one-twenty-five thousandth
of an inch in length. They frequently form jelly-like
masses on the inside of the leaf, these masses consisting
of the bacteria themselves held together by the mucilag-
inous substance they exude.

THE BACTERIAL DISEASE OF C0R;N^ 213

Possible Effect on Cattle. — Investigations made
in Nebraska^ by Dr. F. S. Billings, indicate the proba-
bility, and, in the opinion of Dr. B., the certainty, that
when cattle eat corn affected by this disease the germs
present may cause the illness, and sometimes the death
of the animals. He calls it the "Cornstalk Disease in
Cattle," and concludes an elaborate report of his investi-
gations with this statement; "When cattle become
unaccountably ill immediately after having been turned
into a stripped cornstalk field, and that illness is accom-
panied by the phenomena previously detailed, it may be
taken for granted that it is this corn-fodder disease, and
no other."

Treatment. — No method of preventing the disease
in corn has yet been suggested, except that of crop rota-
tion, and so little is known of what other plants are
attacked by the same germs that this is merely a sugges-
tion. Care should be taken that cattle are not turned
into fields of corn that have patches affected by the dis-
ease ; at least not until all such patches have been cut
and the fodder burned.

Literature. — An account of Professor Burrill's
investigations may be found in the Proceedings of the
Tenth Meeting of the Society for the Promotion of Ag-
ricultural Science (1889, pp. 19-27), and in one of the
earlier Bulletins of the Illinois Experiment Station.
Dr. Billings' investigations are reported in the Bulletin
of the Nebraska Experiment Station (Nos. 7-10, pp.
165-210; June, 1889).

FUNGI AFFECTING BROOM CORN AND

SORGHUM

The Sorghum Blight

Bacillus sorghi

This disease is caused by bacteria, and so is some-
what similar to the bacterial disease of corn already dis-
cussed. It occurs upon both sorghum and broom corn,
and is especially characterized by the red markings it
produces upon affected plants. Its nature was first
worked out by Professor T. J. Biirrill, who gives the

follow^ing description of the external manifestations of
its presence :

^'Sometimes tlie ai^i^earance of injury is noticeable
upon 3'oung j^lants. They grow very slowly, are slender
and yellowish in color, and are easily pulled from the
ground. The lower leaves die, having previously shown
discolored (yellow or red, mostly the latter) patches on
various parts of their surface. Not unfrequently these
conditions prevail in special areas of the field; perhai^s
several acres, not apparently different in composition of
soil, condition of drainage, etc., will have throughout
their extent this dwarfed and sickly crop, while the rest
of the plantation remains healthy and vigorous. More
often the evidence of disease appears, to a greater or less
extent, over the entire field, all, or an exceedingly varia-
ble proportion of the jDlant suffering. Not unfrequently
stalks, four or five feet high, can be lifted with ease from
the soil, the roots being mostly dead and rotten.

'^IJpon the aerial parts the conspicuous evidence of
disease, aside from the smaller size of affected plants, is

214

THE SORGHUM BLIGHT 215

the red-blotched leaves and leaf -sheaths. The latter are
particularly spotted at the upper portion, just below the
ligule. If they are stripped from the stalk the carmine
coloration is seen to be conspicuously brilliant inside,
and often extending over a large area of the interior sur-
face of the sheath. On the leaves themselves the spots
are usually more numerous along the mid-veins. The
stalks are usually not locally affected until late in the
season, when they, too, show eyidence of the disease by
the appearance of red or rusty spots. On the ^^ brush"
of broomcorn similar discolored patches are to be ob-
serye.d, and these directly injure the product. The
rusty, corroded places may be frequently found on the
brush of the manufactured brooms.

"^The diseased roots also turn red but soon decay,
and, of course, lose the bright color. The oldest roots
die first, and, as new ones are successively emitted from
the base of the stem in the order commonly occurring in
these plants, they, in turn, become successively affected
and perish. This is why the plant yields to so slight a
pull,, while healthy ones resist a vigorous effort. Upon
close examination it is evident that the exterior part of
the roots or cortex is the portion in which the disease is
resident, the woody fibers of the interior remaining for a
long time unchanged, except through natural decay
after the death of the whole root. But the woody part
is stained from contact with the external layer."

It has been conclusively shown, both by Professor
Burrill, and by Messrs. Kellerman and Swingle, that
this disease is due to a distinct species of bacteria, re-
quiring a high microscopic power to be seen, and special
skill and training to be successfully studied. When
highly magnified these bacteria bear a general resem-
blance to Fig. 87.

Treatment. — Rotation of crops seems to be the
best method of preventing the development of this dis-

216 FUl^GI AND FUNGICIDES

ease. According to Professor Burrill, ^^ crops are some-
times injured in the way described on land not previ-
ously planted with sorghum or broomcorn ; but the
danger is invariably less," and ^^ field practice has given
excellent demonstration of this system of management."
It is also advisable to burn refuse stalks and stubble, so
far as is practicable.

Literature. — Professor Burrill's article was pub-
lished in the Proceedings of the Eighth Annual meeting
of the Society for the Promotion of Agricultural Science
(1887, pp. 30-36). Messrs. Kellerman and Swingle
have published their results in the report of the Kansas
Experiment Station (1888, pp. 281-302). An additional
note occurs in the Journal of Mycology for December,
1889 (v. 5, pp. 195-199).

The Grain Smut of Sorghum

Ustilago sorghi

The individual seeds of sorghum heads are some-
times attacked by smut. Such seeds become greatly
swollen — especially lengthwise — and consist of a grayish
outer membrane surrounding a mass of dark powder.
The disease is illustrated and briefly described by Pro-
fessor Kellerman, in Bulletin No. 23 of the Kansas Ex-
periment Station.

The Head Smut of Sorghum

Ustilago reiliana

This disease differs from the last in that the whole
head of the sorghum stalk is usually diseased, being
^'converted into a large, continuous, or lobulated mass
covered with a white membrane. The latter soon rup-
tures and exposes the black, powdery mass of spores."
This fungus is discussed and figured in the bulletin
above mentioned.

FUNGI AFFECTING ALFALFA

The Alfalfa Leaf=blight

Cercospora helvola var. medicaginis

This disease has been studied by Professor F. D.
Chester, of Delaware, who reports that it *^ shows itself
upon the leaf as sub-circnlar, or elliptical spots of a
smoky brown, or almost black color, equally visible upon
both sides, and vary-
ing from one-six-
teenth to oue-thirty-
second of an inch in
diameter. The spots
are without well-de-
fined borders, which,
when closely exam-
ined, are somewhat
irregular, shading in-
distinctlv into the
surrounding leaf tis-
sue. Spots coales-
cing cause the leaf to

turn yellow and brown, completely destroying it.
The same fungus is believed, occasionally, to attack
the red clover and scarlet clover, although it is seldom,
if ever, seriously destructive to these crops. The myce-
lium threads of the fungus push about between the cells
of the leaf, absorbing their contents, and causing the
discoloration of the foliage. When ready to fruit, the
threads develop abundantly at certain j^oints just beneath

'217

a

FIG. 88. ALFALFA BLIGHT FUXGUS.
a, Spoi-e; b, section of leaf. Magnified.

>5

218 FUI^GI AXD PUXGICIDES

the epidermis of the leaf, and then push out several
stalks, on the ends of which the sj^ores are produced.
The latter (Fig. 88 a) are long and slender, and divided
by several transverse jiartitions. They germinate when
on moist alfalfa leaves, bv sendins: out a sleiider thread,
which penetrates the skin of the leaf and starts the
funsfus anew.

Treatment. — Upon this point Professor Chester
says : ''In case it should be necessary seriously to com-
bat this difficulty, the writer would advise that all dis-
eased patches or areas be cut and burned, or composted
with an excess of lime."

Literature. — The only article of importance con-
cerniug this disease yet published is the one above re-
ferred to, which may be found iu the Second Report of
the Delaware Experiment Station (1889, pp. 95-97).
Another disease of alfalfa is briefly described in the
same connection, and another in the report for 1890.

FUNGI AFFECTING CLOVER

The Clover Rust

Uromyces trifolii

Although this disease has been known in Europe as
a clover enemy for a long time, it has only recently been
noticed in this country. It is now widely distributed,
however, occurring from Connecticut, in the east, to

FIG. 89.

a, White clover leaf showing secidiuni stage; b, red clover leal showing uredo

stages.

Colorado, in the west. It is occasionallv so abundant
as to injure seriously fields of red clover. Leaves affected
by the disease are more or less thickly covered with
Avell-rlefined, oblong, brown powdery spots, as shown in
Fig. 89.

219

220

rUXGI AND FUXGICIDES

Like various other members of the family of rusts
to which this fungus belongs, it exists in three distinct

FIG. 90. CLOVER RUST,

c, Cluster-cups and secidium spores; d, uredo spores ;/, uredo pustule on clover
leaf; e, teleiito spores; fj, cross-section of stem showing mycelium between
cells; also two teleuto spores and one uredo spore.

successive stages. Early in the season it appears — prin-
cipally upon white clover plants — in the so-called cecid-

THE CLOVER RUST . 221

ium stage. It affects both the leaves and stems, produc-
ing cup-like swellings, which are filled with orange
colored spores. A white clover leaf attacked by this
stage of the fungus is shown in Fig. 89 a, while at c,
Fig. 90, may be seen two of the cluster-cups magnified,
and some of the orange colored spores still more enlarged.
These orange spores are blown to other clover plants,
especially red clover, where they germinate and send
their little tubes into the leaf tissues. These tubes start
the mycelium which develops between the leaf cells for
some time before any external indication of its presence
occurs. Then it produces, at certain places just beneath
the outer skin of the leaflets, numbers of small reddish-
brown spores, which finally rupture the skin (as seen in
Fig. 90/), and are set free. When magnified {d) these
spores are shown to have their outer surfaces studded
with minute pointed tubercles. This is the second, or
uredo stage of the fungus ; these spores are called uredo-
spores. After these are mostly blown away — presumably
to start the disease in new situations — there is produced
from the same mycelium, and in the same spots, the third
form of spores called the teleuto-spores {e). These are
supposed to carry the fungus through the winter, although
it is probable that it also passes the winter in the myce-
lium in white clover 2)lants.

Treatment. — According to Miss J. K. Howell, of
the Cornell University, to whom we are indebted for
much of our knowledge of this disease, the early croj) of
red clover is not likely to be injured by rust. In conse-
quence, she makes the following suggestions as to rem-
edies : ''As the second crop is likely to suffer greatly if
the midsummer is cool, and as clover becomes a valuable
fertilizer when plowed in, the fields should be carefully
watched in such seasons, and the crop might be plowed
under to advantage. Burning the clover fields in the
fall would probably have some effect in checking the

222

FUNGI Ais'D FUXGICIDES

spread of the disease during the next season ; but the
application of fungicides seems impracticable."

Literature. — The most complete account of this
disease in American literature is that of Miss Howell,
referred to above, which is found in Bulletin 24 of the
Cornell Experiment Station. Professor Pammel has
discussed it in Bulletin No. 13 of the Iowa Station ; and
various notes concerning it have been published elsewhere.

INDEX

Alfalfa, Fungi aftecting,

leaf-blight,
Apple, Fungi affecting,

bitter rot,

powdery mildew,

rot,

ripe rot,

rust,

scab,

twig blight, . *

Ascochi/ta petimice,
Bacillus sorghl,
Bean, Fungi affecting,

anthracnose,

blight,

pod spot,

rust.
Beet, Fungi affecting,

leaf -spot,

rust,
Bordeaux mixture,

and arsenites,
Broom corn, Fungi affecting.
Cabbage, Fungi affecting,

club root.
Carbonate of copper,
Carnation leaf-spot,

rust,
Catalpa leaf-spot.
Cauliflower, Fungi affecting.
Celery, Fungi affecting,

blight,

leaf-blight,

soft-rot,
Ceratocystis Jiinbriatcif

9

— 5

Page

217

217

27

33

30

33

33

36

27

39

125

214

129

129

132

129

132

135

136

135

15

20

2U

138

138

18

121

120

111

138

144

144

146

149

172

223

224

FUXGI AXD FUNGICIDES

Cercospnra angulala,

" heticola,

" helvola,

" re.^e<ke.

Cherry, Fungi affecting,

brown rot,

black knot,
Chester spraying cart,
Cladosporium carjxtjih Hum,
Clover, Fungi affecting, .

rust,
Cccoma nitrna,
Colletulrich um Icujenariuin,

" spinacece,

Conidia,
Copper arsenic solution, .

chloride,
Cottonwood leaf-rust.
Cucumber, Fungi affecting,
Cm-rant, Fungi affecting,

anthracnose,

leaf-spot,
Cylindrosporium padi,
Damping-off fungus,
Eau celeste,

Entomospnrium maculatum.
Flowers, Fungi affecting,

carnation rust,
" leaf-siDot,

hollyhock rust,

mignonette disease,

petunia blight,

verbena mildew,
Fungi, losses due to,

methods of studying,
" " distribution.
" " preventing,

parasitic,
Fungicides, application of

the important

and insecticides

use of
Fus icladl um den drit ic ii m ,

pi/rinu)n,

Pasre

1»1

lU
IM)
217
1-2S

()()

GO

2:\

02

210

219

U)l

120

177

/

2(1

10

112

loo

01

92

91

0;J

182

17

41, 47

110

120

121

110

12:5

12.">

124

1

11

11

12

9

21
14
20
14
27
40

li^^DEX

225

>g''

Fudsporium culmorum,
Glceosporium fructlgenum,

nervisequum,

ribis,

venetum,
Gooseberry, Fungi affecting,

leaf-spot,

mildew,
Grape, Fungi affecting,

anthracnose,

black rot,

brown rot,

downy mildew,

powdery mildew,
Gymnosporaugium,
Hollyhock rust,
Indian corn, Fungi affect

bacterial disease,

rust,

smut.
Knapsack sprayer,
L (est a< I la h id well i,
Lima bean mildew,
Macrosporium solanij
INIaple leaf-spot,
Melampsora pop ulina,
Melons, Fungi affecting,

bacterial blight,

leaf-spot,

mildew.
Micrococcus amylovorus,
Mignonette disease.
Modified eau celeste,
MonlUa fruGtifjenaj
Mushrooms,
Nozzles,

Oats, Fungi affecting,
loose smut,
rust,
Oldium erysipMoides,
Onion, Fungi affecting,
mildew,
S'mut,

spot diseases,
Oospora scabies f

15

Page

198

33

113

92

97

91

91

93

79

87

79

82

82

85

36

119

202

209

207

202

22

. 79

133

165

113

112

160

160

163

160

44, 51

123

18

66, 73
4
22
187
187
193
124
150
150

2, 152
157
168

226

FUXGI AND FUi^-GICIDES

Parasitic fungi,
Peach, Fungi affecting,

brown rot,

leaf-curl,

rosette,

yellows,
Pear, Fungi affecting,

blight,

leaf-blight,

Pcronospora,

cj/'usa,

schleideniana,

vit'icola,
Petunia blight,
Phyllosticta acericola,

" catalpce,

Pliragm idium m ucrotiat urn,

" specioswii,

Phytoplwra phaseoli,
Plasmodiophora brassiav,
Plasm opara c uhen sis,
Plo icrigh t ia m o rhosa ,
Plum, Fungi affecting,

black knot,

brown rot,

fruit scab,

fruit spot,

leaf-blight,

leaf rust,

pockets,
Podosphcera oxyacantJicf,
Potato, Fungi affecting,

bacterial blight,

downy mildew,

early blight,

late blight,

leaf-spot,

scab.
Potassium sulj^hide,
Puccinia mcdvacearum,

" maydis,

" priini-spinosce,

" 7'ubiyo-vera,
Pythium De Baryanum,

Page
2,5

67

73

67

. 73

68

41

44

41

46

8

176

150

82

125

113

111

115

117

133

138

160

53, 66

53

53

56

62

63

63

65

60

30

164

165

6,164

164

164

164

168

19

119

207

68

200

182

INDEX

227

Quince, Fungi affecting,

black rot,

fruit spot,

leaf-blight,

rust, •

twig-blight,
Rasj^berry, Fungi affecting,

anthracnose,

orange rust,
Roestelia,

" aurantiaca,
Rose, Fungi affecting,

mildew,

phragmidiuni,

rust,
Saprojihytes,
Saprophytic fungi,
Sept 07' la cerasina,

" dianthi,

" pet7-oselini,

" 7'ibis,
Shade trees, Fungi affecting,

catalpa leaf-spot,

Cottonwood leaf-rust,

maple leaf-spot,

sycamore blight,
Soda hyposulphite.
Sorghum, Fungi affecting,

blight,

grain smut,

head smut,
Spliaceloma ampelinum,
Sphcerella frarjarke,
Sphceropsis malorum,
iSphcetvtheca mo?'s-uva',
" pcmnosa,

Spinach, Fungi affecting,

anthracnose,

mildew,
Spraying pumps,

" bushes.
Strawberry, Fungi affecting,

leaf-blight,
Sulphate of copper,
Sulphur^

Page

47

50

47

47

49

51

97

97

101

36

49

114

114

117

115

5

5

64

121

146

91

111

111

111

113

113

19

214

214

216

216

87

104

50

93

114

176

177

176

00

23

104

2, 104

19

20

228

FUXGI AXD FUN-GICIDES

Sycamore blight,

Sweet potato, Fungi affecting,

black rot,
Swai in spores,
Taphrina deformanst,

pruni,
TiUetia foetenii,
Tomato, Fungi affecting,

bacterial blight,

rot,

winter blight,
Uncin uln cniijjelopsld /'.■<,
Urocj/sfis cfipnia',
Uromi/ces hetce,

carpophilliniis, .
phaseoli,
trifolii,
Ustllar/o acence,

" reiliana,

" sorf/hi,
iritici,
zece-mays,
Verbena mildew,
Vermiculdria circinan.%
Water,
Wheat, Fungi affecting,

bunt,

loose smut,

rust,

scab,

stinking smut.
Weather, relation to diseases,
AVinter spores,

Page
113

172

172

8

67

60

194

179

180

179

180

85

152

135

120

132

219

187

216

216

198

202

124

157

15

194

194

198

1,200

198

194

10

10

SEMT Kree on Application.

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RURAL BOOKS,

CONTAINING IIG 8vo. PAGES,
PnopusELY Illustrated, anb giving Full Desckiptions ov

NeAELT 600 WOKKS ON THE FOLLOWING SUBJECTS:

Farm and Garden,

Fruits, Flowers, Etc.

Cattle, Sheep, and Swine,

Dogs, Horses, Riding, Etc.,

Poultry, Pigeons, and Bees,

Angling and Fishing,
Boating, Canoeing, and Sailing,

Field Sports and Natural History,

Hunting, Shooting, Etc.,
Architecture and Building,

Landscape Gardening,

Household and Miscellaneous.

PUBLISHERS AND IMPORTERS :

ORANGE JUDD COnPANY,

52 & ?4 Lafayette Place, New York.

Books will be Forwarded, postpaid, on receipt of Price.

standaeI/ books.
Mushrooms : How to Grow Them.

Any one who has an ordinary house cellar, "woodshed or barn, can
grow Mushrooms. This is the most practical work on the subject
ever written, and the only book on growing Mushrooms published
in America. The author describes how he grows Mushrooms, and
how they are grown for profit by the leading market gardeners, and
for home use by the most successful private growers. Engravings
drawn from nature expressly for this work. By Wm. Falconer.
Cloth. Price, postpaid. 1.50

Land Draining;.

A Handbook for Farmers on the Principles and Practice of Drain-
ing, by Manly Miles, giving the results of his extended experience
in laying tile drains. The directions for the laying out and the
construction of tile drains will enable the farmer to avoid the
errors of imperfect construction, and the disappointment that
must necessarily follow. This manual for practical farmers will
also be found convenient for references in regard to many ques-
tions that may arise in crop growing, aside from the special sub-
jects of drainage of which it treats. Cloth, 12mo. 1.00

Allen's New American Farm Book.

The very best work on the subject; comprising all that can be con-
densed into an available volume. Originally by Richard L. Allen.
Revised and greatly enlarged by Lewis F. Allen. Cloth, 12mo. 2.50

Henderson's Gardening: for Profit.

By Peter Henderson. The standard work on ^Market and Family
Gardening. Tlie successful experience of the author for more than
thirty years, and his willingness to tell, as he does in this work, the
secret of his success for the benefit of others, enables him to give
most valuable information. The book is profusely illustrated.
Cloth, 12m o. 2.00

Henderson's Gardening: for Pleasure.

A ginde to the amateur in the fruit, vegetable and flower garden,
with full descriptions for the greenhouse, conservatory and window
garden. It meets the wants of all classes in country, city and vil-
lage wno keep a garden for their own enjoyment rather tlian for
the sale of products. By Peter Henderson. Finely Hlustraled.
Cloth, 12mo. 2.00

Johnson's How Crops Grow.

New Edition. A Treatise on the Chemical Composition, Structure
and Life of the Plant. Revised Edition. This book is a guide to
the knowledge of agricultural plants, their composition, their
structure and modes of development and growth ; of the complex
organizations of plants, and the use of the parts; the germination
of seeds, and the food of plants obtained both from the air and
the soil. The book is a valuable one to all real students of agricul-
ture. With numerous illustrations and tables of analysis. By Prof.
Samuel W. Johnson of Yale College. Cloth, 12mo. 2.00

STAI^DARD BOOKS.

Johnson's How Crops Feed.

A Treatise on the Atmosphere and the Soil, as related in the
Nutrition of Agricultural Plants. This volume— tlie companion and
complement to "How Crops Grow"— has been welcomed by those
who appreciate the scientific aspects of agriculture. Illustrated.
By Prof. Samuel W. Johnson. Cloth, 12mo. 2.00

Market Gardening: and Farm Notes.

By Barnet Landreth. Experiences and Observations for both
North and South, of interest to the Amateur Gardener, Trucker and
Farmer. A novel feature of the book is the calendar of farm and
garden operations for each month of the year; the chapters on
fertilizers, transplanting, succession and rotation of crops, the
packing, shipping and marketing of vegetables, will be especially
useful to market gardeners. Cloth, 12mo. 1.00

Forest Planting;.

A Treatise on the Care of Woodlands and the Restoration of the
Denuded Timber-Lands on Plains and Mountains. By H. Nicholas
Jarchow, LL. D. The author has fully described those European
methods which have proved to be most useful in maintaining the
superb forests of tiie old world. This experience has been adapted
to the different climates and trees of America, full instructions be-
ing given for forest planting on our various kinds of soil and sub-
soil, whether on mountain or valley. Illustrated, 12mo. 1.50

Harris* Talks on Manures.

By Joseph Harris, M. S., author of "Walks and Talks on the Farm,"
"Harris on the Pig," etc. Revised and enlarged by the author. A
series of familiar and practical talks between the author and the
Deacon, the Doctor, and other neighbors, on the whole subject of
manures and fertilizers: including a chapter especially written for
it, by Sir John Bennet Lawes of Rothamsted, England. Cloth,
12mo. 1.75

Truck Farming: at the South.

A work which gives the experience of a successful grower of vege-
tables or " truck" for Nortiiern markets. Essential to any one who
contemi^lates entering this promising field of Agriculture. By A.
Oemler of Georgia. Illustrated, cloth, 12mo. 1.50

Sweet Potato Culture.

Giving full instructions from starting the plants to harvesting and
storing the crop. With a chapter on the Chinese Yam. By James
Fitz, Keswich, Va., author of "Southern Apple and Peach Culture."
Cloth, 12mo. .60

Heinrich's Window Flower Garden.

The author is a practical llorist, and tliis enterprising volume em-
bodies his personal experiences in Window Gardening during a
long period. New and enlarged edition. By Julius J. Heinrich.
Fully illustrated. Cloth, 12mo. .75

STANDARD BOOKS.

Greenhouse Construction.

By Prof. L. R. Taft. A complete treatise on GreeiilioiTse structures
and arrangements of the various forms and styles of Plant Houses
for professional floi-ists as well as amateurs. All the best andmost
approved structures are so fully and clearly described that anyone
who desires to build a Greenhouse will have no difficulty in deter-
mining the kind best suited to his purpose. The modern and most
successful methods of heating and ventilating are fully treated
upon. Special chapters are devoted to houses used for the growing
of one kind of plants exclusively. The construction of hotbeds
and frames receives appropriate attention. Over one hundred ex-
cellent illustrations, specially engraved for this work, make every
point clear to the reader and add considerably to the artistic ap-
pearance of the book. Cloth, 12mo. 1.50

Bulbs and Tuberous-Rooted Plants.

By C. L. Allen. A comi^lete treatise on the History, DescriiJtion,
Methods of Propagation and full Directions for the successful cul-
ture of Bulbs in the garden. Dwelling and Greenhouse. As gener-
ally treated, bulbs ai'e an expensive luxtiry, while, when properly
managed, thej^ afford the greatest amount of pleasure at the least
cost. The author of this book has for many years made bulb grow-
ing a specialty, and is a recognized authority on their cultivation
and management. The Illustrations Avhich embellish this work
have been drawn from nature, and have been engraved especially
for this book. The cultural directions are plainly stated, practical
and to the point. Cloth, 12mo. 2.00

Henderson's Practical Floriculture.

By Peter Henderson. A guide to the successful propagation and
cultivation of florists' plants. The work is not one for florists and
gardeners only, but the amateur's wants are constantly kept in
mind, and we have a very complete treatise on the cultivation of
flowers under glass, or in the open air, suited to those who grow
flowers for pleasure as well as those who make them a matter of
trade. Beautifully illustrated. New and enlarged edition. Cloth,
12mo. 1.50

Lon§:*s Ornamental Gardening: for Americans.

A Treatise on Beautifying Homes, Rural Districts and Cemeteries.
A plain and practical work at a moderate price, with numerous
illustrations and instructions so plain that they may be readily
followed. By Eli as A. Long, Landscape Architect. Illustrated,
Cloth, 12mo. 2.00

The Propa§:ation of Plants.

By Andrew S. Fuller. Hlustrated with numerous engravings. An
eminently practical and useful work. Describing tlie process of
hybridizing and crossing species and varieties, and also the many
different modes by which cultivated plants may be propagated and
muiUplicd. Clotli, 12mo. 1.50

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