Fungi and fungicides

Fungi and fungicides.

oa —~ LIBRAPY
OF .
STATE HORTICULTURAL COMMISSIDONALD REDDICK

ELLWOOD COOPER, Commissioner

FUNGI AND
F JNGICIDES

SACRAMENTO
W. W. SHANNON, SUPT. STATE PRINTING

1905

CALIFORNIA STATE COMMISSION OF
HORTICULTURE.

ELLWOOD COOPER -....------ Commissioner -.-.---------- Santa Barbara.

JOHN TSWA Ch aces, - eed Secretary oc geese oessnsesd San Francisco.

ED. M. EHRHORN ---.--.----- Deputy --2sssnscsceeecseens Mountain View:

Hy Ki. CARN HS wcasecessscsuezes Assistant Deputy ---.------------ Riverside.

O. E. BREMNER .-.-.----2----- Second Assistant ---.--.------- Santa Rosa.

GERTRUDE BIRD .-.------- ..--Stenographer -_.._-----------.- Sacramento.
OFFICE:

Room 41, Srate CarrroL, SACRAMENTO.
s

Brancu Orrice, Room 11, Ferry Burupine, San FRANcIsco.

FUNGI AND FUNGICIDES.

Growing plants are liable to the attacks not only of insects,
but also of parasitic fungi. The peculiar maladies known as
fungous diseases are produced by the rapid development of the
parasitic fungi. It is estimated that in the United States alone
the annual loss from these minute vegetable organisms runs
into millions of dollars.

Fungi belong to the so-called lower plants, among which are
the toadstool, mushroom, molds, mildews, rusts, smuts, blights,
etc. A fungus may attack only dead tissue or decaying matter,
as is the case with mushrooms or toadstools, or it may attack only
animal life, as is seen in the fungus which destroys the house
fly and the chinch bug. But the most important class of para-
sitic fungi with which the fruit-grower has to deal are those
which attack the live tissue of plant life—those which check
the growth of trees, attack and spot fruit, and even cause an
early decay or a total loss before the crop is harvested.

Fungi are plants, much the same as trees, grass, etc., the
only difference being that they do not have the green coloring
matter, or chlorophyll, of the latter. The seeds, called spores,
are more simple and are exceedingly minute (microscopic).
They are produced in numbers which appear almost incredible
to those not versed on the subject.

Fungi are divided into two groups: the internal and the
external. The internal fungi send their germ tubes into the
skin of the leaf, fruit, branch, or root, and the branching
threads (mycelium) develop entirely within the tissue of the
host plant. This group includes some of our worst species, such
as peach-leaf curl, anthracnose, brown rot, shothole fungus,
and all the grain smuts. _

The external fungi are surface feeders, their mycelium spread-
ing over the surface of the fruit, leaf, or branch, as the case
may be, and are easily controlled by the use of sprays. To this
group belong the powdery mildews of the apple, grape, rose,
gooseberry, etc.

4 FUNGI AND FUNGICIDES.

It will be readily seen that quick action, perseverance, and
good judgment on the part of the grower are necessary to
obtain satisfactory results. Especially is this true of the
internal fungi, which must be attacked before the germ-tube
enters the tissue.

PEACH-LEAF CURL.

In some seasons this fungus is very severe, and on some
varieties of peach more than on others. It can be easily
recognized by the abnormal growth of the leaf, which becomes
leathery, highly colored, and sometimes resembles a seed-pod
more than a leaf.

In winter use the lime-sulphur-salt wash or the Bordeaux
mixture (formula A).

Just as the buds are swelling use the Bordeaux mixture
(formula B).

APPLE OR PEAR SCAB.

Thisis one of the most common diseases of pomaceous fruits
the world over. It does not reduce the crop, nor does it seem to
@ affect the vitality of the

tree, but it injures the
quality of the fruit, mak-
ing it unsalable. The
grower knows too well
that a scabby or a de-
formed pear has no sale
in the market or at the
cannery, in fact is only fit
for hog feed; therefore,
the utmost vigilance and
greatest care should be
exercised in the applica-
tion of remedies to check
‘ this disease. The first
Fro. g. Tue, feet ot she fungus gp.c7s "4 appearance of the scab is
seen upon the new growth

and small fruit as a velvety spot. The disease is easily recog-
nized, and'if not soon checked the velvety spots on the fruit
continue to spread until they have the appearance of black,
scabby, corky blotches. As the pears grow, the development
of the affected side is arrested, but the healthy side continues

FUNGI AND FUNGICIDES. 5

to develop very fast and begins to twist or double over the
affected side, making a very ugly looking, misshaped fruit.
Spray with the lime-sulphur-salt wash as late in winter as
possible.
Spray with the Bordeaux mixture (formula A) while the
buds are unfolding. If the season permits, a second and third
spraying, ten days apart, using formula B, will prove beneficial.

SHOTHOLE FUNGUS.

This disease has, of late, become very prevalent, attacking
all the stone fruits, and has been especially destructive to the

Fic. 2. Appearance of the fungus on an apple. Fic. 3. A bloteh—enlarged.

apricot. It makes its appearance upon the leaves, forming
reddish-brown spots, which, when mature, shrink from the
surrounding tissue and are blown away, leaving the leaf
perforated. When the fungus attacks the fruit, it first appears
as minute red pimples, which are very often mistaken for scale
insects. These soon develop and burst open at the top, the
new spores escaping and spreading the disease. The old spot
forms a scab, which spreads and joins others, and soon the
surface becomes very rough, rendering the fruit unsalable.

Spray with the lime-sulphur-salt solution in winter, and use
the Bordeaux mixture (formula B) just when the buds are
swelling. If the lime-sulphur-salt remedy is not used, then
the Bordeaux mixture (formula A) should be applied as early
in the season as possible.

6 FUNGI AND FUNGICIDES.

BROWN ROT.

The brown or fruit rot of stone fruits is known in but few
localities in the State. Wherever this disease occurs, its pres-
ence is shown by the ashy gray spores on the surface of the
fruit. Sometimes, where several fruits are clustered together,
a small brown spot appears and rapidly spreads until the
whole becomes shrunken, soft, and discolored. The interior

Fic. 5. Pear cracking. Fic. 6. Leaf blight.

of fruits which do not indicate much outward attack will show
a brownish, rotten appearance when cut open.

-Wherever the disease exists, care should be taken to gather
all diseased fruit, generally known as mummied fruit, which
may cling to the fruit spurs or fall to the ground, as the spores
thereon will infect the next year’s crop.

The same remedies as are used for pear scab will check this
disease.

FUNGI AND FUNGICIDES. 7

POWDERY MILDEW OF APPLE, PEACH, AND OTHER TREES.

During the summer months one may notice the leaves and
new growth of fruit trees covered with a thick, white, felt-like
covering. These are the mycelium of the powdery mildew
fungus. This fungus belongs to the external group, the
mycelium of which live on the outside of the plant and do not
enter the tissue of the leaf. Early in the fall of the year the
winter spores are developed and consist of very minute, round,
black masses, which remain on the fallen leaves or twigs dur-
ing the winter and from which start the next season’s brood.

Use the ammoniacal solution of copper carbonate when the
leaves first open, and in very bad cases repeat three or four
times at intervals of fourteen days.

BITTER ROT OF THE APPLE.

This fungus has appeared in various apple districts. The
time to spray for it is when it first makes its appearance.
This disease can be easily recognized by the presence of small
blackish pustules scattered over the surface of the apple.
These are the fruiting spots of the fungus. The mycelium
enter the pulpy tissue of the fruit and cause the rot to appear
in little brown specks underneath the skin.

In very bad cases the first spraying should be followed by a
second and third spraying at intervals of two weeks, using the
ammoniacal copper carbonate solution.

PRUNE-LEAF RUST.

The leaves of the prune and other stone fruits are often
attacked by reddish spots on the surface and yellowish-brown
spots on the under side. Sometimes this attack is so severe
as to cause the dropping of the foliage.

Spraying with the Bordeaux mixture (diluted formula) just
after the buds start, and continued at intervals of ten or
fourteen days during the growing season, will do much toward
checking the fungus.

PEAR BLIGHT.

This disease, while not belonging to the group of fungous
diseases on which we are treating, has become so important in
this State and is doing such destructive work that allusion to

8 FUNGI AND FUNGICIDES.

it in this connection is imperative. The pear blight is caused |
by a bacterium discovered by Prof. T. J. Burrill, of Illinois,”
and by him named Bacillus amylovorus. Its point of entry
into the tree is usually through the blossoms, although in some
cases it may find entry through wounds or abrasions in other
portions. The whole of the pomaceous family, including
apples, medlars, hawthorns, and quinces, is subject to attack,
but the pear especially so, and the tenderer varieties, as the
Bartlett, most of all. This disease has received marked atten-
tion from the Department of Agriculture at Washington, D. C.,
on account of the serious inroads it has made in the pear sec-
tions of the East, and Prof. M. B. Waite has made an especial
study of it for many years past. In response to an invitation
from the Commission of Horticulture last fall, Professor Waite
was detailed to study the disease in California, and under his
direction a series of experiments has been made. So far the
only method of fighting this disease, and the one which has
been in vogue for many years in the East, is to cut out the
affected portions of the tree well below the point of infection.
An important feature of this work is the disinfection of the
tools used in the cutting-out process. Unless this is properly
done, the tools themselves may become the medium of distribu-
tion of the disease. Professor Waite is positive in his assertion
that if the work of cutting out the infected portions is con-
scientiously and generally performed, there is little danger to
be apprehended from this disease.

GOOSEBERRY MILDEW.

In some sections of the State it is almost impossible to raise
good gooseberries, on account of mildew. This fungus appears
in the spring upon the newly developed leaves and buds, and
later appears as a white powdery mass, caused by the numerous
summer spores. Later in the season it attacks the young
berries, which are rendered unmarketable, or in very bad cases
the entire crop drops prematurely.

Spray with a solution of potassium sulphide when the leaves
commence unfolding, and repeat in from two to three weeks.

During the winter remove all old canes and spray with the
Bordeaux mixture (formula B).

FUNGI AND FUNGICIDES. 9

ANTHRACNOSE.

Affecting the Raspberry, Blackberry, and Rose.

This fungus appears as small reddish-purple spots upon the
canes and leaves in the spring and early summer. These spots
are scattered over the surface of the new growth near the
ground, and have a distinct purplish margin, representing the

Fic. 7. Rose leaf black spot. Fic, 8. Strawberry leaf blight.

‘

division between the healthy and diseased tissue. As the
season advances these spots increase in size, and, merging with
others, form irregular, longitudinal blotches, which in very
bad cases girdle the cane.

Use the Bordeaux mixture (diluted formula) before the
leaves open, and repeat at intervals of two weeks, spraying the
canes which are starting out of the ground.

Removing the old canes and burning them will greatly
reduce the disease.

10 FUNGI AND FUNGICIDES.

ORANGE RUST.

This disease is familiar to most growers of blackberries and
raspberries. The disease becomes noticeable soon after the
leaves expand in the spring, turning them a golderr color.,
Soon small orange-colored spores appear on the surface of the
leaves. From these spores develop the winter spores, which
spread to the growing shoots just starting from the ground and
remain there until spring, to again infest the plant.

All diseased canes should be cut and burned whenever dis-
covered. Spraying with the ammoniacal copper carbonate
solution will prove helpful, if applied on the winter spores.

ONION MILDEW.

California, with her large seed gardens, has suffered very
much from onion mildew in abnormal seasons. The seed
onions carry the hibernating spores, which soon attack the new
growth in spring. The disease is easily recognized by the
grayish, velvety coating on the new tops and blossom stalks.
If the land is to be used again for onions, all tops remaining
in the field after the seed has been collected should be burned,
and should never be plowed under, as is generally practiced.
Rotation of crops is much the safer preventive.

Wherever practicable, the ammoniacal copper carbonate
solution can be used to good advantage.

BEAN ANTHRACNOSE.

Young bean pods are often attacked by this disease, some
varieties more than others. It can be readily recognized by
small reddish-brown spots, slightly depressed, on the surface
of the pods. These spots increase in size rather rapidly and,
connecting with others, form long discolored blotches. The
pod becomes stunted and the young beans are generally shriv-
eled. Seed from diseased plants should never be used for
planting, as the spores upon them will first infest the young
growing plants and from them spread to the newly developed
pods.

Soaking the seed in a diluted ammoniacal copper carbonate
solution before planting is a sure preventive. Spraying with
the Bordeaux mixture (diluted formula) has given good results.
Burning the old plants after harvest and making a clean cul-

“ture in general have much to do with a successful checking of
the fungus.

FUNGI AND FUNGICIDES. 11

TOMATO ROT.

When the fruit of the tomato is about half grown it is sub-
ject to the attack of rot. The first appearance of this disease
is a small blackish-brown spot, which rapidly increases in size.
The underlying tissues of the fruit are destroyed by the fun-
gous threads, and the side of the fruit affected becomes flattened.

Wherever this disease appears it can be checked to a certain
degree by thinning out the plants and allowing more sunshine
to reach the fruit.

Spraying with the Bordeaux mixture (formula B) when the
fruit is first forming will often check the fungus.

POTATO BLIGHT OR ROT.

This disease attacks the leaves, stems, and tubers. It is first
noticed upon the leaves by the sudden appearance of brownish
or blackish areas, which soon become soft and foul-smelling.
This disease generally occurs in our coast counties and other
sections where plenty of moisture exists. The presence of a
few successive hot, dry days in these districts checks its rapid
development.

Spraying with the Bordeaux mixture (formula B) when the
growth just appears above ground, especially in sections where
this fungus is known to exist, is very important. Affected
potatoes should never be used for seed, and all vines remain-
ing after harvest should be burned.

POTATO SCAB.

This is a very widespread disease, and is readily recognized
by the dark, rough surface which occurs in spots all over the
tubers.

This disease can be successfully controlled by treating the
seed potatoes in a solution of corrosive sublimate. Immerse
them for a couple of hours in the liquid, and after their re-
moval allow them to dry before cutting them for planting.
All potatoes thus treated, if not planted, must be destroyed, as
there is sufficient poison on them to make them dangerous to
use as food or to feed to stock.

12 FUNGI AND FUNGICIDES,

ROOT KNOT.

No fungous disease is easier recognized than this. The very
prominent black or brown wart-like excrescences upon the
trunk and roots, below ground, of all stone-fruit trees, readily
reveal its presence.

Cut away the knot in the fall or winter and allow the wound
to dry, then with a swab apply a saturated solution of blue-
stone to the affected part.* This may be repeated two or more
times as long as the trees remain dormant. Never apply it to
the tree when the sap is flowing. After the knots have been
treated the soil is thrown back again, covering the exposed
roots. The Bordeaux mixture (formula A), applied in a sim-
ilar way, has also given good results. Instead of removing very
large knots it is better to bore an inch hole to the center of the
knot and fill this with either of the above solutions, which will
permeate the tissues of the knot and cause it to drop off after
a few months.

OLIVE KNOT.

One of the most serious diseases of the olive tree, in a few
counties of California, is the olive knot, or tuberculosis of the
olive, as it is sometimes called, which, like the pear blight, is
a bacterial and not a fungous disease. The tubercles, or knots, °
which give this disease its name, are found singly and in rows
on branches of all ages. The bacteria which cause the disease
form a colony in the tissue of the sap-wood, which appears
like a small, transparent spot. This spot, when seen under a
high-power microscope, is found to consist of many bacteria.
From this spot soon develop, through different stages, the
tubercle knots. On the trunks and larger branches the knots
generally attain a large size.

The diseased parts of affected trees should be carefully re-
moved and immediately burned. All wounds made by the
removal of the disease should be dressed with an antiseptic
paint.

Cuttings from diseased trees should never be used for prop-
agating purposes.

*A saturated solution of bluestone is all that water will dissolve. But it
is advisable to leave some undissolved bluestone in the bottom of the vessel,
as this will indicate that the water has taken up all the bluestone it can.

Fig. 9. Olive knot.

14 FUNGI AND FUNGICIDES.

POWDERY MILDEW OF THE ROSE.

This disease is too well known to the lovers of tea roses to
need much description. It is the white powdery fungus which
is so often seen on the new growth, leaves, and buds of the
rose bush, marring the beauty and blasting the buds of many
of our choicest varieties.

If taken in hand when it first makes its appearance on the new
growth, dusting with sublimed sulphur will check its spread.
Spraying with the Bordeaux mixture (diluted formula), just
before the new growth starts, will prevent its appearance.

Fic. 10. Rose rust.
ROSE RUST.

This disease confines itself to the hybrid perpetual roses,
and is easily recognized by the orange-colored spots on the
under side of the leaves, which in very bad cases become
entirely covered.

After pruning rose bushes in the fall, they should be thor-
oughly sprayed with the Bordeaux mixture (formula B). All
leaves should be gathered and burned, as these contain the
winter spores. If the fungus was very severe during the
season, Spraying again in the spring, just when the growth
starts, with the ammoniacal copper carbonate solution or the
Eau Celeste solution, will greatly aid in checking the trouble.

FUNGI AND FUNGICIDES. 15

FORMULAS.

LIME, SULPHUR AND SALT.

WHSIAKE ONT C1 ted othe eee acest ery hyenas 40 pounds,
CS 01] § 0) D501 ee eee care mane te Se ea OED REN SURE od 20 pounds.
Pcp iSite tc aetagestsaS minne ele te ia re tnes 15 pounds.
Wiiiteric cos escioceienetentenn eins too big eeeeerserecauens 60 gallons.

Place 10 pounds of lime and 20 pounds of sulphur in a boiler
with 20 gallons of water, and boil over a brisk fire for not less
than one hour and a half, or until the sulphur is thoroughly
dissolved. When this takes place, the mixture will be of an
amber color. Next place in a cask 30 pounds of unslaked lime,
pouring over it enough hot water to thoroughly slake it; and
while it is boiling, add the 15 pounds of salt. When this is
dissolved, add to the lime and sulphur in the boiler, and cook
for half an hour longer, when the necessary amount of water
to make the 60 gallons should be added.

A much easier method of preparing the above wash is as
follows: Make the sulphur into a thin paste with hot water;
place the unslaked lime in a tight barrel and add the sulphur
paste and from 10 to 15 gallons of boiling water. Cover the -
*var-el with sacks and a wooden cover and let it stand. After
the violent boiling has subsided, the mixture must be stirred
thoroughly until all indications of boiling stop. Then add the
salt and enough hot water to be able to strain the mixture into
the spray tanks, and add the required quantity of boiling

water.
BORDEAUX MIXTURE.

Formula A.

Copper sulphate (bluestone)...-.-..-.. -.--------. -. 8 pounds.
Quicklime..ccicciecmawserateeeacactianmesisicciiicine, eaes 10 pounds.
Watteres cceccreewsi noratceuniecleckiishiccl enaseedaeS 50 gallons.
Formula B.
Copper sulphate (bluestone) -- 5 pounds.
QuieKime: . ona. sot ese eee woe aa as ee esesesS 6 pounds.
WiateQna 22 oio 2 chen ee Sk seap ese1 ceegeseeeete occa Paces 50 gallons.
Diluted Formula.
Copper sulphate (bluestone) -----_-----------.-------- 2 pounds.
QnickliMe: on. cec eee terdenes ene ise louetnebateees 2 pounds.
Weateticces cessor nGcntccc tee tiesoescsiduaetnetentis 30 gallons.

Dissolve the copper sulphate in a barrel containing 10 to 12
gallons of water. Slake the quicklime and thin it to a creamy

16 FUNGI AND FUNGICIDES.

whitewash. Pour the whitewash very slowly through a wire
screen into the copper solution. Stir the mixture thoroughly,
and add enough water to make 50 gallons in all. Stir occa-
sionally while applying as a spray to the trees.

In the preparation of the Bordeaux mixture it is necessary
that the ingredients should be mixed in a wooden vessel. If
an iron one is used the copper will go to the iron and the effect
of the spray be largely neutralized.

Apply the wash cold and as soon as possible after it is
prepared. Never allow it to stand over night.

AMMONIACAL COPPER CARBONATE SOLUTION.

Copper carbonate .-_ ___.--_---------------..------ --- 6 ounces
ATOMIONID) = 553222 bo esate emcee ens someensoe ee 3 pints.
VEST ia poepey adap geyser Acne eget eI cstocindat 50 gallons.

Dissolve the copper carbonate in the ammonia and add the
water.

Caution: Use no more ammonia than is required to dis-
solve the copper carbonate. Ammonia is variable in strength,
and the amount required must be tested in practice.

POTASSIUM SULPHIDE SOLUTION.

Potassium sulphide-_---.----.--.-. ------------------ 1 ounce.
LOE WAP esi a ees ioneartiaiue rset sieatn oariseeroue 2 gallons.

Dissolve the potassium in hot water, and use as a spray
when cold.

EAU CELESTE SOLUTION.

Copper polos Jovebiechaests 2 pounds.
Ammonia -- - 1 quart.
Wiater en 25 osteo --- 50 gallons.

Dissolve the copper sulphate in 6 gallons of water, using a
wooden vessel, then add one quart of ammonia and sufficient
water to make 50 gallons of wash.

CORROSIVE SUBLIMATE SOLUTION.

Corrosive sublimate: 2. 2ccc eee Seed 2% ounces.
Ot WAteRacaccie chicane: setae somata eae 2 gallons.

Dissolve the corrosive sublimate in the water, let it stand
for about 10 hours, and then add sufficient water to make 15
gallons of spray.