The control of peach brown-rot and scab

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Do not assume content reflects current
scientific knowledge, policies, or practices

U. S. DEPARTMENT OF AGRICULTURE.

BUREAU OF PLANT INDUSTRY -BULLETIN NO. 174.

B. T. GALLOWAY, Chief of Bureau.

THE CONTROL OF PEACH BROWN-ROT

AND SCAB.

W. M. SCOTT, Pathologist,

AND

T. TYTLLARD AYRES, Scientific Assistant,
Fruit-Disease Investigations.

Issued March 5, 1910.

WASHINGTON:

government printing office,
1910.

BUREAU OF PLANT INDUSTRY.

Chief of Bureau, Beverly T. Galloway.

Assistant Chief of Bureau, G. Harold Powell.
Editor, J. E. Rockwell.
Chief Clerk, James E. Jones.

■ Fruit-Disease Investigations.

scientific staff.

Merton B. Waite, Pathologist in Charge.

W. M. Scott and C. L. Shear, Pathologists.

W. S. Ballard, L. A. Hawkins, George F. Miles, P. J. O'Gara, F. V. Rand, J. W. Roberts, and J. M.

Shull, Assistants.
Clara H. Hasse and Anna K. Wood, Laboratory Assistants.
174
2

LETTER OF TRANSMITTAL

U. S. Department of Agriculture,

Bureau of Plant Industry,

Office of the Chief,

Washington, D. C, December lo, 1909.
Sir: I have the honor to transmit herewith a manuscript entitled
4 'The Control of Peach Brown-Rot and Scab," by Mr. W. M. Scott,
Pathologist in Charge of Orchard Spraying Experiments and Demon-
strations, and Mr. T. W. Ayres, Scientific Assistant, Fruit-Disease
Investigations, and recommend it for publication as a bulletin of the
special series of this Bureau.

The summer spraying of peaches has for years been a puzzling
problem on account of the injury to the foliage resulting from the use
of various mixtures. After repeated trials a fungicide was found in
1907 in the form of self-boiled lime-sulphur which prevents diseases
without injury to the foliage.

The experiments with this material were repeated on a larger scale
in 1908. During the past season (1909) the treatment was demon-
strated on a block of 5,000 trees and further details were worked out
by experiment. The present paper describes these demonstrations
and experiments and gives a summary of the three seasons' work,
with recommendations for the treatment of orchards.
Respectfully,

B. T. Galloway,

Chief of Bureau.
Hon. James Wilson,

Secretary of Agriculture.

174

CONTENTS.

Page.

Introduction 7

Peach brown -rot 8

History of the disease 8

Economic importance of the disease 9

Nature of the disease and the fungus causing it 11

Influence of the weather 12

Influence of insects 13

Peach scab 13

Character of the disease 13

Economic importance of the disease 14

Spraying for the control of peach brown-rot and scab in 1909 14

Preparation of self-boiled lime-sulphur mixture 15

Self-boiled lime-sulphur treatment and results 16

Commercial results 17

Self-boiled lime-sulphur and arsenate of lead in combination 18

Commercial results 19

Marketing test 20

Cost of the treatment 21

Danger of injury to the fruit and foliage 22

Danger of staining the fruit 22

Results obtained by growers in commercial orchards 23

Course of treatment recommended 24

Brown-rot, scab, and curculio treatment 25

Brown-rot and scab treatment 26

Scab treatment 26

Application of the spraying mixtures 26

Description of plates 28

Index 29

174 5

ILLUSTRATIONS

PLATES.

Page.
Plate I. Peaches affected with brown-rot, showing the destructive work of the

disease and the rotten, moldy appearance of the fruit Frontispi ece

II. Two crates of Elberta peaches picked from the experimental plats at
Fort Valley, Ga., on July 9, 1909, shipped by refrigerator car to
New York, and then by express to Washington, D. C, showing the
difference in the amount of brown-rot developed 28

III. Peach scab. Fig. 1. — Two unsprayed Elberta peaches affected with

scab, showing the black spots and cracks produced by the disease.
Fig. 2. — Crop from an unsprayed Elberta peach tree, showing all
the fruit affected with scab and 86 per cent of it unmerchantable.
Sleepy Creek, W. Va., August 27, 1909. 28

IV. Peach scab. Fig. 1. — Crop of Elberta peaches from a tree sprayed

once with self-boiled lime-sulphur. Good, merchantable fruit in
the pile and unmerchantable, scabby fruit on the notebook at the
top. Sleepy Creek, W. Va., August 27, 1909. Fig. 2.— The same
unsprayed crop shown in Plate III, figure 2, sorted for the market.
The large pile on the right is unmerchantable, scabby fruit, that
on the left representing all that was suitable for packing 28

TEXT FIGURE.

Fig. 1.— An old brown-rot mummy with the cup-shaped bodies (apothecia) of

the fungus, in which myriads of ascospores are produced 12

174
6

B. P. I.— 538.

THE CONTROL OF PEACH BROWN-ROT AND

SCAB.

INTRODUCTION.

The susceptibility of peach foliage to injury from applications of
the usual copper fungicides has largely prohibited summer spraying for
the control of peach diseases. The diseases preventable by dormant
spraying, such as leaf-curl and the California peach blight, have
been easily overcome, but those requiring summer treatment have,
as a rule, been allowed to go unchecked for the want of a suitable
fungicide. The peach has therefore largely had to fight its own
battles against some of its worst enemies, with the result that the
growers of this fruit have annually sustained heavy losses.

During the past few years the Bureau of Plant Industry has
endeavored to develop U fungicide that could be safely used on the
peach during the growing season to prevent some of the diseases of
the fruit and foliage. Various copper compounds in both liquid and
dust form were tested without satisfactory results. Experiments
with sulphur in various forms showed that the soluble sulphids were
even more caustic than Bordeaux mixture, and no encouragement
was obtained from the work until the so-called self-boiled lime-
sulphur mixture was tested.

In the experiments of 1907, the results of which were published in
Circular No. 1 of the Bureau of Plant Industry, a it was found that
self -boiled lime-sulphur could be used as a spray on the peach without
injury to fruit or foliage. Brown-rot infections were held down to
10 per cent of the crop, while 73 per cent of the fruit on the unsprayed
trees rotted. The same treatment prevented the peach scab, or
black-spot, and some leaf diseases.

Experiments conducted by the writers during 1908 at Marshall ville,
Ga., Bentonville, Ark., and Neoga, 111., verified the previous year's
results and gave sufficient data to warrant the recommendation of
tins mixture for general use in peach-growing districts where brown-
rot and scab are prevalent. The results of the 1908 experiments,
with suggestions for the treatment of brown-rot and scab, were pub-
lished in Circular No. 27 of the Bureau of Plant Industry.

a These results were first reported by the writer at the Jamestown meeting of the
American Pomological Society, September 25, 1907, and were published in the pro-
ceedings of that meeting. They were also presented before the Missouri State Hor-
ticultural Society, December 5, 1907, by Mr. F. W. Faurot, who assisted in the work.
174 7

8 CONTROL OF PEACH BROWN-ROT AND SCAB.

During the past season (1909) the work on this important problem
was carried out on a large scale somewhat in the nature of a demon-
stration. The results of this work, together with directions for pre-
paring and applying the mixture for the treatment of brown-rot and
scab, are presented in the following pages.

The peach grower now has at his command an effective weapon
with which to combat two of his worst fungous enemies — brown-rot
and scab. In view of the excellent results obtained from the experi-
ments of the past three years, the writers are of the opinion that
self-boiled lime-sulphur will soon become almost, if not quite, as
indispensable to the peach grower as Bordeaux mixture has been
to the apple grower.

PEACH BROWN-ROT.

HISTORY OF THE DISEASE.

The fungus causing brown-rot was first described by Persoon a in
1796 as Torula fructigena, and he later transferred it to the genus
Monilia. In 1893 Schroter b placed the fungus in the ascomycetous
genus Sclerotinia, although its perfect stage was not known until
discovered by Norton0 in 1902. The fungus is reported by Saccardo d
as occurring in Great Britain, Germany, France, Italy, Belgium, and
Austria, as well as in the United States. Perhaps the first to recog-
nize it as of economic importance were Von Thumen6 and Hallier^
and it has been discussed by Frank/ Prilleux/- Wehmer/ Sorauer/
Woronin,fc Aderhold/ and other European writers who have con-
tributed largely to our knowledge of the life history of this fungus.

In the United States this disease has been known for many years
and has had more or less attention from nearly all the pathologists of this
country. In 1881 Peckm gave what appears to be the first economic
account of the disease, and since that time it has been the subject
of study by a large number of investigators, notably Arthur,™ Gallo-

° Observationes Mycologicae, vol. 1, p. 26.

b Kryptogamen Flora von Schlesien, vol. 3, Pilze, p. 67.

c Transactions, Academy of Science, St. Louis, vol. 12, no. 8, 1902, pp. 91-97.

^Sylloge Fungorum, vol. 4, 1886, p. 34.

« Oesterreiches Landwirtschaftlich.es Wochenblatt, no. 41, 1875, p. 484; see also
Fungi Pomicoli, 1879, pp. 22-24.

/Wiener Obst- und Garten- Zeitung, 1876, p. 117.

^Krankheiten der Pflanzen, 2d ed., vol. 2, 1896, p. 360.

^Maladies des Plantes Agricoles, vol. 2, 1897, pp. 449-453.

*Berichte der Deutschen Botanischen Gesellschaft, vol. 16, 1898, pp. 298-300.

./Berichte der Deutschen Botanischen Gesellschaft, vol. 17, 1899, pp. 186-189.

ll Memoires de l'Academie Imperiale des Sciences de St.-Petersbourg, ser. 8, vol.
10, no. 5, 1900, pp. 18-29.

I Berichte der Deutschen Botanischen Gesellschaft, vol. 22, 1904, pp. 262-266.
™ Thirty-fourth Report, New York State Museum, Natural History, 1881, pp. 34-36.

« Fourth Report, New York Agricultural Experiment Station, 1886, pp. 281-285.
174

PEACH BROWN-ROT. 9

way/' Erwin F. Smith,6 Humphries0 and Quaintance.d Vari >us
other articles dealing principally with the treatment of this disease

have appeared in bulletins of the state experiment stations and of
the United States Department of Agriculture, and in agricultural
journals.

Hygienic measures, such as the removal of rotting and mummied
fruits and the priming out of diseased twigs, have been strongly
recommended for the control of brown-rot, and most writers have
advised spraying with dilute Bordeaux mixture; but only in rare
instances have these remedial measures been successful. In spite of
the fact that in a wet season when treatment is most needed Bordeaux
mixture and other copper compounds injure peach leaves and defoli-
ate the trees, nearly all the recent publications on the subject have
recommended spraying with these fungicides, the authors believing
that the benefit would more than counterbalance the injury.

ECONOMIC IMPORTANCE OE THE DISEASE.

With the possible exception of peach yellows, which kills the tree
outright, brown-rot has for years been recognized as the most destruc-
tive disease of stone fruits, such as peaches, plums, and cherries. It
also affects the apple, pear, and quince, but only in rare cases does
it become a serious pest on these pomaceous fruits. The disease is
well distributed over the United States, and in most of our humid
sections it has practically prohibited the commercial production of
the European plum and often destroys a large portion of the crops of
peaches, Japanese plums, and cherries. The average annual loss to
the peach growers of this country easily reaches S5, 000, 000. Quaint-
ance e estimated the loss in Georgia for the year 1900 at from $500,000
to 8700,000. The number of bearing trees in that State has more
than doubled since that time and the brown-rot has not abated in the
least, so that a conservative estimate of the loss at the present time
with a fair crop of fruit set and under average brown-rot conditions
would be SI, 000, 000; in fact, the writers are convinced that the loss
during the past season, with only a third of a crop, almost reached
that figure. Similar losses occur in other Southern States, and the
more northerly peach districts are b}" no means exempt. Dr. Erwin
F. Smith / placed the loss on the Chesapeake and Delaware peninsula

a Report, Commissioner of Agriculture, 1888, pp. 349-352.

t> Journal of Mycology, vol. 5, no. 3, 1889, pp. 123-134; also vol. 7, no. 1, L891,
pp. 36-39.

c Eighth Report, Massachusetts Agricultural Experiment Station, 1891, p. 213; also
Botanical Gazette, vol. 18, 1893, pp. 85-93.

<* Bulletin 50, Georgia Agricultural Experiment Station, 1900, pp. 237-269.

« Bulletin 50, Georgia Agricultural Experiment Station, 1900, p. 245.

/Journal of Mycology, vol. 5, no. 3, 1889, pp. 123-134.
21263— Bui. 174—10 2

10 CONTROL OF PEACH BROWN-ROT AND SCAB.

in 1888 at 800,000 baskets (of five-eighths of a bushel), worth $400,000,
which he considered a very conservative estimate. The same writer
states that the following spring (April and May, 1889) this section
experienced an outbreak of the brown-rot on the blossoms and young
fruits which destroyed the greater part of the peach crop in four
counties, resulting in a loss of at least 500,000 baskets.

Dr. C. P. Clinton a reports that in Connecticut " brown-rot of
peaches and plums is always present at harvest time, some seasons
becoming so prevalent that it sweeps away a large part of the profits
in a few days." The same may be said of the prevalence of this dis-
ease in Michigan, Missouri, Arkansas, and in other peach-growing
States.

In California, Prof. Ralph E. Smith b reported that during 1905
and 1906 the brown-rot was " quite abundant and destructive on
apricots, some plums, and early peaches, especially near the coast."
It has also been reported from Oregon by Prof. A. B. Cordley c as
causing excessive rotting of plums in 1897 and 1898 and to a less
extent affecting peaches.

The effect of this disease does not cease with the fruit growers, but
is felt by the transportation companies, the commission men, and
the consumers. Although the fruit may be carefully sorted at the
packing house and only sound specimens packed, the disease often
continues to develop en route to market, especially if the refrigera-
tion is not good. In an orchard where the disease is prevalent, the
healthy fruits easily become contaminated through handling by the
pickers and packers, and enough moisture develops in the car through
the " sweating" of the fruit to germinate the spores. It thus not
infrequently happens that peaches from the Southern States reach
the market " specked" and must be sold at half the value of sound
fruit. The commission man is often blamed by the shipper for the
low returns received, when the trouble is really due to brown-rot.
Qn several different occasions the senior writer has been in the New
York market when from thirty to over a hundred cars of southern
peaches were sold from 2 to 6 o'clock in the morning and 25 to 50 per
cent of the fruit from a large number of these cars was found to be
affected with brown-rot. In recent years this condition has so often
prevailed that the board of health of New York City deemed it neces-
sary to designate a special health officer whose duty is to inspect the
fruit as it is unloaded from the cars and prohibit the sale of such as
is badly affected with brown-rot. Fruit arriving in poor condition
demoralizes the market to such an extent that where 50 cars of sound

a Report, Connecticut Agricultural Experiment Station, 1903, p. 286.
& Bulletin 184, California Agricultural Experiment Station, p. 248.
c Bulletin 57, Oregon Agricultural Experiment Station, pp. 3-5.
174

1

PEACH BROWN-ROT. 11

peaches may be readily sold at good prices 15 or 20 cars of fruit
specked with brown-rot are sufficient to create a "glut" and often
bring scarcely enough to pay expenses.

NATURE OF THE DISEASE AND THE FUNGUS CAUSING IT.

Brown-rot is a fungous disease which affects the fruit of the peach,
causing it to decay on the trees or en route to market. As already
stated, it is caused by a fungus whose botanical name is Sclerotinia
fructigena (P.) Schrdt. Many fruit growers call it Monilia, the name
given to the summer stage of the fungus before the perfect form was
known. The fungus also attacks the blossoms and twigs, thus often
destroying a portion of the fruit crops at blooming time. The dis-
eased blossoms turn brown and become dried, adhering to the twigs
for some weeks. The fungus may extend from the dead blossom into
the bark, forming a small brown canker which frequently girdles the
twig. In low, damp situations, especially in a wet spring, many
blossoms and fruit-bearing twigs may thus be destroyed. Some of
the green fruits may become affected at anytime during the season,
and even young peaches half an inch or less in diameter may rot, but
as a rule no serious outbreak occurs until the fruit is nearing maturity.
It is at harvest time ordinarily that the greatest destruction is
wrought.

On the fruit, brown-rot may at first be observed as a small circular
brown spot, which under favorable conditions rapidly enlarges, until
within two or three days the entire peach goes down in decay. While
the spot is yet small, whitish tufts of spore-bearing threads begin to
appear. As the spot enlarges, these tufts, arranged more or less in
concentric rings, become so numerous as nearly to cover the surface,
giving the diseased area a grayish, mold}' appearance. (See PL I.)
Most of the rotten fruit drops to the ground, but a considerable por-
tion of it may shrivel up on the tree and remain attached until the
following season. As in the case of diseased blossoms, the fungus
may extend from the rotting peaches into the twigs, killing them and
thus reducing the prospects of a crop the following year. In a wet
season some varieties suffer so badly from twig infections that the
trees have the appearance of a pear tree attacked by blight.

The fungus passes the winter in the mummified peaches hanging
on the trees, as well as in those that have fallen to the ground.
During the spring and summer, especially in wet weather, the fungus
in these mummies produces large crops of summer spores for the
infection of the new fruit crop. In the mummies on the ground the
fungus forms a black leathery sclerotium, which is the foundation of
another kind of spore production. In the spring, during the blooming
period, small, brown cup-shaped bodies (apothecia), resembling toad-

174

12

CONTROL OF PEACH BROWN-ROT AND SCAB.

stools, about one-half inch in diameter, are produced from mummies
which have remained on the ground through two winters partially or
entirely covered with soil. (See tig. 1.) One mummy may produce
ten to fifteen of these bodies, each of which produces myriads of
ascospores. When disturbed by a puff of wind a little cloud of spores
may be seen to rise into the air from one of the cups. These ascospores
as well as the conidia, serve to infect the blossoms. A crop of sum-
mer spores is in turn produced on the diseased blossoms and some of
the young, green fruits become infected by these, so that there is
usually a great abundance of material ready for the infection of the

mature crop of fruit,
even if the old mummies
have been removed from
the trees.

It has for years been
recommended that the
rotten fruit be picked
from the trees and from
the ground and destroy-
ed in order to remove
the source of infection
for the following year's
crop. This is a good
practice, but it is usually
disappointing, because
the fungus is so prolific
in spore production that
the few mummies that
inevitably escape the
pickers are sufficient to
furnish the initial infec-
tion material for the en-
tire crop of the following year. ' Protection of the fruit by spray-
ing appears to be the only satisfactory means of combating this
fungus, although the destruction of diseased fruits doubtless aids in
checking it and should not be discouraged.

Fig. 1.— An old brown-rot mummy with the cup-shaped bodies
(apothecia) of the fungus, in which myriads of ascospores
are produced.

INFLUENCE OF THE WEATHER.

Most parasitic fungi are influenced by weather conditions. This
is especially true of the brown-rot fungus. Moisture not only favors
the growth of the fungus and the production and germination of the
spores, but it also renders the fruit tender and watery and therefore
more susceptible to rot. In a dry season, or one with only occasional
rains of short duration, a peach crop may be expected to reach maturity
practically free from rot, particularly if the weather is cool; but when

174

PEACH SCAB. 13

a series of cloudy days with frequent showers occurs about picking
time, half or even all of the crop may be destroyed by brown-rot.
Prolonged cloudy, drizzly weather, even though the precipitation
may not be great, is far more dangerous than a heavy rain followed by
clearing. Hot weather also favors the rapid growth of the fungus
and increases the danger of its destroying the crop.

INFLUENCE OF IXSECTS.

The spores are undoubtedly distributed broadcast by the wind, so
that they are in most cases ever present on the fruit ready to pro-
duce an outbreak of the disease when the conditions are favorable.
Although the fungus appears to be able to enter the peach through
the unbroken skin, entrance is more readily accomplished through
abrasions such as are made by insects and through cracks due to the
scab fungus. Sucking insects of the squash-bug family (Coreidae) have
been observed to puncture healthy and diseased fruits indiscrimi-
nately, a thus not only distributing the spores but probably inserting
them into the peach. But the curculio is by far the worst offender.
It breaks the skin of the peach and leaves a wound through which
the fungus readily gains entrance. Although the wound may appar-
ently heal before an outbreak of rot occurs, an exudation of gum often
keeps it open sufficiently to admit the fungus. The work of this
insect greatly reduces the efficiency of fungicides applied for the con-
trol of brown-rot. It punctures the fruit through the coating of
spray, possibly inserting brown-rot spores and certainly leaving an
opening for the fungus. In experiments conducted by the Bureau of
Plant Industry in cooperation with the Bureau of Entomology it was
found that 93 per cent of the brown-rot infections on sprayed fruit
had taken place through curculio punctures. It is evident, therefore,
that in order to secure the best results from spraying for brown-rot,
the curculio must also be controlled.

PEACH SCAB.
CHARACTER OF THE DISEASE.

Peach scab is a disease caused by the fungus Cladosiwrium carpo-
pMlum Thum. It is also known as black-spot, and peach growers
often call it ''freckles/' which is an appropriate name, owing to the
freckled appearance the disease gives to the fruit. The spots are
dark brown or blackish, circular in outline, and about one-eight h of
an inch or less in diameter. They are often so numerous that one
side of the peach has a ''smutty" or blackish appearance, cracks open,
and shrivels. (See PI. Ill, figs. 1 and 2.)

a Scott and Fiske. Bulletin 31, Division of Entomology, U. S. Dept. of Agricul-
ture, p. 29.
174

14 CONTROL OF PEACH BROWN-ROT AND SCAB.

The disease mars the appearance of affected fruit, reducing its
market value and often rendering much of it unsalable. The large
cracks which occur in severe cases open the way for brown-rot, and
in addition the skin under the individual spots is usually broken,
exposing the peach to attacks of the fungus. Preventing the scab is
therefore an important step in the control of brown-rot.

The fungus forms brown spots on the twigs where it passes the
winter. So far as is known at present, these twig spots are the chief
source of infection of the fruit. Fruit infection begins to take place
about three to four weeks after the petals fall, although the spots do
not show until about three weeks later. Infections continue to take
place until about a month before the fruit matures.

ECONOMIC IMPORTANCE OF THE DISEASE.

Peach scab has been known in this country for many years, and
it occurs to an injurious extent wherever peaches are grown east of
the Rocky Mountains. The damage done by this disease is appar-
ently not fully realized by peach growers. Scab spots are so com-
mon on the peach that most of the eastern growers have come to
take the disease as a matter of course and scarcely realize that their
fruit is bringing 25 per cent less in the market than the same fruit
free from scab would bring. Moreover, the fungus has a tendency
to dwarf the fruit and prevent it from attaining full size, so that a
considerable loss in yield is thus sustained.

On the other hand, some growers recognize it as their worst enemy,
and in many localities it practically prohibits the growing of certain
varieties. Some of the large orchards in the mountains of West Vir-
ginia and western Maryland have sustained heavy losses from this
disease, and the growers have been obliged to confine their plantings
of such late varieties as Bilyeu and Salway to the high ridges in order
to avoid scab. The Bilyeu is very valuable commercially, but the
scab has restricted its successful production to the higher points.

It has been known for some years that peach scab could be con-
trolled by applications of Bordeaux mixture, but its use for this pur-
pose has been discouraged by its injurious effects upon peach foliage.
The disease has therefore been practically without a satisfactory
remedy.

SPRAYING FOR THE CONTROL OF PEACH BROWN-ROT AND SCAB

IN 1909.

As stated in the introduction of this paper, peach brown-rot and
scab were effectively controlled by spraying with a self-boiled lime-
sulphur mixture in experiments conducted during 1907 and 1908.
The work of 1907 was confined to small plats in one orchard, while
that of 1908 involved several orchards in different localities, aggre-
gating about 2,000 trees.

174

SPRAYING FOR CONTROL OF PEACH BROWN-ROT AND SCAB. 15

During 1909, in order to place the treatment on a better commercial
basis, large blocks of several different varieties, comprising over 5,000
trees, were sprayed. This was more in the nature of a demonstration
than an experiment, although some features of the work were purely
experimental, as will be seen in the following pages. In addition
to this block, about 7,000 trees in the same orchard were sprayed
by the owner under the supervision of the writers.

The work was conducted in the orchard of the Hale Georgia
Orchard Company, at Fort Valley, Ga., and the writers are indebted
to Mr. J. H. Hale, president of the company, and Mr. J. H. Baird,
its superintendent, for their hearty cooperation and valuable assist-
ance. This orchard was in good condition, having been well cul-
tivated, fertilized, and pruned, but in recent years the brown-rot
had become exceedingly bad. The crop of 1908 was largely lost
on account of brown-rot, scab, and curculio, and the conditions were
particularly favorable for a severe test of the self-boiled lime-sulphur
treatment. Unfortunately, however, in this orchard, as in most
of the Georgia orchards the past season, the crop was very light for
all varieties and the yield per tree quite low, but the value of spraying
was, nevertheless, strikingly demonstrated.

The spraying was done with a power outfit consisting of a 2-horse-
power gasoline engine, a triplex pump, a 200-gallon tank, a propeller
agitator, two 25-foot leads of discharge hose, Vermorel nozzles, etc.
The mixture was prepared according to the following formula and
directions.

PREPARATION OF SELF-BOILED LIME-SULPHUR MIXTURE.

The mixture used in our experiments during the past season was
composed of 8 pounds of fresh stone lime and 8 pounds of sulphur
(either flowers or flour may be used) to 50 gallons of water. This
appears to be about the correct strength, although in mild cases of
scab and brown-rot a weaker mixture, containing 6 pounds of each
ingredient to 50 gallons of water, may be used with satisfactory
results. The mixture can best be prepared in rather large quantities —
say, enough for 200 gallons at a time, making the formula 32 pounds
of lime and 32 pounds of sulphur, to be cooked with a small quantity
of water (8 or 10 gallons) and then diluted to 200 gallons.

The lime should be placed in a barrel and enough water poured on
to almost cover it. As soon as the lime begins to slake the sulphur
should be added after first running it through a sieve to break up the
lumps. The mixture should be constantly stirred and more water
added as needed to form a thick paste at first and then gradually a
thin paste. The lime will supply enough heat to boil the mixture
several minutes. As soon as it is well slaked, water should be added

174

16 CONTROL OF PEACH BROWN-ROT AND SCAB.

to cool the mixture and prevent further cooking. It is then ready
to be strained into the spray tank, diluted, and applied.

The stage at which cold water should be poured on to stop the cook-
ing varies with different limes. Some limes are so sluggish in slaking
that it is difficult to obtain enough heat from them to cook the mix-
ture at all, while other limes become intensely hot on slaking and care
must be taken not to allow the boiling to proceed too far. If the
mixture is allowed to remain hot fifteen or twenty minutes after the
slaking is completed, the sulphur gradually goes into solution, com-
bining with the lime to form sulphids, which are injurious to peach
foliage. It is therefore very important, especially with hot lime,
to cool the mixture quickly by adding a few buckets of water as soon
as the lumps of lime have slaked down. The intense heat, violent
boiling, and constant stirring result in a uniform mixture of finely
divided sulphur and lime, with only a very small percentage of the sul-
phur in solution. The mixture should be strained to take out the
coarse particles of lime, but the sulphur should be carefully worked
through the strainer.

SELF-BOILED LIME-SULPHUR TREATMENT AND RESULTS.

Several different varieties of peaches were sprayed with good
results. The details of the work were about the same in each case,
the following notes on the Waddell variety serving as an example
of the treatment given and the results obtained :

Plat 1, consisting of 568 Waddell trees, was sprayed with self-
boiled lime-sulphur (32-32-200) on April 30, about one month after
the petals dropped, and again on May 20, three to four weeks before
the fruit ripened. At picking time the entire crop, including dropped
fruit from five average trees in this plat, was sorted and counted,
with the result that 17 per cent was found to be affected with brown-
rot. An examination of the rotting fruits showed that 93 per cent
of the infections had taken place through curculio punctures and
that aside from such infections only 1 per cent of the crop was affected
with brown-rot.

From a commercial standpoint, the scab or black-spot was com-
pletely controlled, although 16 per cent of the fruit showed some
slight infections. None of the fruit was sufficiently spotted to injure
its market value.

Check A consisted of 1,357 unsprayed Waddell trees in a block
adjacent to plat 1. Of the fruit from five average trees in this block
49+ per cent was affected with brown-rot and 9H per cent with scab.
About one-third of the scabby fruit, or 28^ per cent of the total crop,
was so badly spotted and cracked that it had to be discarded as
unmerchantable. In this case 81 per cent of the brown-rot infec-

174

SPRAYING FOR CONTROL OF PEACH BROWX-ROT AND SCAB. 17

lions had apparently taken place through curculio punctures. In
the actual counts of diseased specimens from plat 1. as compared
with the unsprayed plat, there was a difference in favor of spraying of
32^ per cent in the case of brown-rot and 75J per cent in the case of
scab. These figures do not tell the whole story. The sprayed fruit
was larger, more highly colored, and presented a much better appear-
ance in the package: it carried to the market in better condition and
commanded a higher price than the unsprayed fruit.

Plat 2 was a block of 1,275 Waddell trees sprayed only once to
determine the value of a single application. The spraying was done
en April 30, a month after the petals dropped. The intention was
to make this application at a time when it would be expected to
accomplish the best results against scab. The Waddell is one of
the worst of the early varieties to scab, and to control this disease is
an important step in the control of brown-rot.

The sorting record of the fruit from five trees in this block showed
that 32 per cent was affected with scab and 12^ per cent with brown-
rot. The percentage of scabby fruit ran rather high, but the spots
were mostly small and scattered, so that only 2 per cent of the crop
was badly affected. If the disease is kept down to two or three
spots on each fruit the damage is very slight even though a large
percentage of the crop may be so affected. The unsprayed trees of
this variety, as pointed out above, had 91^ per cent of the fruit
affected with scab, while 28^ per cent of the crop was so badly spotted
with the disease as to be unmerchantable. One spraying, therefore,
made a difference of 59^ per cent in the amount of fruit affected
with scab and resulted in an actual saving of 26^ per cent of the
crop from destruction by scab.

COMMERCIAL RESULTS.

In order to determine the commercial results a record was made
of the marketable fruit from each plat. The fruit was brought into
the packing house, sorted, and packed in the usual way. The number
of trees in each plat varied, ranging from 568 to 1,357, and for con-
venience of comparison the average yield for 500 trees in each plat
is given as follows: Plat 1, 160 crates: plat 2, 170 crates; and the
check or unsprayed plat, 80 crates.

This record of yield corresponds closely to the results expressed in
percentages of diseased fruit as determined by sorting the crop from
five trees in each plat. In such large plats considerable variation in
the trees and environment would naturally be expected and there
was perhaps a sufficient difference between plat 1 and plat 2 to
account for the fact that the latter, which was sprayed only once,
had less brown-rot and more good fruit than the former, which was

174

18 CONTROL OP PEACH BROWN-ROT AND SCAB.

sprayed twice. The check plat, which lies between plats 1 and
certainly represents something near the average conditions for tl
whole block involved and the difference in yield between the spraye(
and the unsprayed trees was, for the most part, undoubtedly due
to the effect of the spraying. The application of self-boiled lime-
sulphur, therefore, apparently increased the yield by 100 per cent, j

SELF-BOILED LIME-SULPHUR AND ARSENATE OF LEAD IN COMBINATION]

It has been known for many years that the curculio is an important
factor in the distribution of brown-rot and that to prevent the former
would be an important step toward controlling the latter. In our
first lime-sulphur experiments during 1907 the interference of this
insect with the efficacy of spraying for the control of brown-rot was
again clearly brought out. In discussing the results of that year's
work the senior writer stated that athe plum curculio punctures the
skin of a certain percentage of the fruit and admits the fungus in
spite of all spraying that can be done."a Although in most of ouJ
experiments the brown-rot has been held down by spraying to about]
10 to 15 per cent where the unsprayed fruit ran 50 to 70 per centoJ
brown-rot, it has nevertheless been apparent in all ■ the work thai
spraying for brown-rot would not be entirely satisfactory so long as
the curculio was not also controlled.

Entomologists have known for many years that the curculio could
be controlled by the application of arsenical poisons, but owing to the
danger of injury to both fruit and foliage they have very properrd
been cautious about recommending their use on peach trees. Mr. Aj
L. Quaintance, of the Bureau of Entomology, during the past five oi
six years, has experimented extensively on the use of arsenate oi
lead for spraying peach trees, with the result that a high percentage
of curculio injury was always prevented by two or three sprayings
beginning soon after the petals dropped. In 1905 he recommended
with due caution the spraying of peach trees with arsenate of lead fo
the control of this insect.6 Mr. E. P. Taylor,0 of the Missouri Fruit
Experiment Station, recently reported that during 1908 he hac
obtained a high percentage of fruit free from curculio by the use oa
arsenate of lead, with very little injury to the foliage. He also noted
a very marked reduction of brown-rot on the sprayed trees.

In order to test the practicability of combining arsenate of lead
with self-boiled lime-sulphur as a combination treatment for scabj
brown-rot, and curculio, one of our principal experiment blocks at
Fort Valley, Ga., was devoted to this purpose. This work was car-]

a Circular 1, Bureau of Plant Industry. U. S. Dept. of Agriculture, 1908, p. 1G.
6 Yearbook, U. S. Dept. of Agriculture, for 1905, p. 329.
c Journal of Economic Entomology, vol. 2, 1909, p. 156.
174

J

SPRAYING FOR CONTROL OF PEACH BROWN-ROT AND SCAB.

19

ried on in cooperation with Mr. Quaintance. A block of 2,324 Elberta
peach trees, 7 years old, was selected for this test and nearly half
of it sprayed, the remainder being left unsprayecl as a check The
results of 'the treatment were exceedingly satisfactory, as will be seen
in the following notes. «iiaa*

The treated portion, designated as plat 6, consisted of 1,100 trees,
not quite half of the block. These trees were sprayed as follows:

(1) With arsenate of lead, 2 pounds to 50 gallons of water, on March 31 aa the dried
ca yces (or shucks, were shedding This application was intended for the curculio
only, and as the date was too early for serious brown-rot and scab infection the lime-
sulphur was omitted. ,. ,

(2) With 8-8-60 self-boiled lime-sulphur and 2 pounds of arsenate of lead combined,
on April 22. three weeks after the first treatment.

(3) With self-boiled lime-sulphur alone, on May 21.

(4) With self-boiled lime-sulphur alone, on June 9, about one month before the frutt

ripened. .

The curculio treatment necessitated an extra application betore
the time to begin using the fungicide, thus increasing the cost. How-
ever the cost of materials, labor, and teams for these four sprayings
was only $62 38 or 5| cents for each tree. Moreover, the writers are
of the opinion that only three applications, as outlined below, will be
required to secure satisfactory results, thus reducing the cost, lhe
trees were watched closely throughout the season and no injury to
fruit or foliage was observed.

When the mature fruit, including windfalls, from five average trees
in this plat was sorted and counted, it was found that only 4* per cent
was affected with brown-rot, about half of which apparently resulted
from curculio punctures. Only 6| per cent of the fruit showed scab
infections, and these were mostly small, obscure specks. The cur-
culio infestation was 27 1 per cent of the crop.

The check was composed of 1,224 unsprayed Elberta trees adjacent
to the sprayed block. The trees in the two blocks were of the same age
and were growingunder the same conditions of soil, cultivation, etc. , the
only difference being that one block was sprayed and the other was
not' The fruit from five of the unsprayed trees when sorted proved to
be 63 per cent rotten, 99 per cent scabby, and 97J per cent wormy
from curculio. In other words, the crop was practically a total loss
A comparison of these figures with those of plat 6 (the sprayed part)
shows that spraying saved 58* per cent of the crop from brown-rot,
92 i per cent from scab, and 70 per cent from curcuho.

COMMERCIAL RESULTS.

A record kept in the packing house showed that the sprayed block
of 1 100 trees yielded 327i crates of first-class fruit, while the un-
sprayed block of 1,224 trees yielded only 33i crates, all of which were
poor in quality. At the beginning of the season the set of fruit

174

20 CONTROL OF PEACH BROWN-ROT AND SCAB.

appeared to be about equal in the two blocks, but was very light in
both. So far as could be determined, the difference in yield was due
entirely to spraying. It appears, therefore, that in the combined
self-boiled lime-sulphur and arsenate of lead spray we have an effect-
ive remedy for the peach scab, brown-rot, and curculio, the yield
from the sprayed trees in this instance being ten times that from the
unsprayed trees.

MARKETING TEST.

In order to determine the carrying quality and market value of the
sprayed as compared with the unsprayed fruit, two cars of peaches
from the experiment blocks were shipped to New York, examined on
arrival, and sold in the usual way through a commission house. This
test was accomplished through the cooperation of Mr. Hale and the
Georgia Fruit Growers' Exchange.

The fruit for the first car was picked on Friday, July 9, in a drizzling
rain, but was not loaded and billed out until the following day. It
was due on the New York market the following Tuesday morning,
but was delayed en route and was not sold until Wednesday morning,
July 14. This car contained Elberta peaches from the lime-sulphur-
arsenate-of-lead block and from the adjacent check block, Belle
peaches sprayed three times with lime-sulphur alone, and unsprayed
Belles. The market was almost glutted with poor fruit and the
prices were at about the lowest point of the season. The fruit was
sold at the following prices:

Sprayed Elbertas $2. 00 per crate.

Unsprayed Elbertas 1. 50 per crate.

Sprayed Belles 1. 25 per crate.

Unsprayed Belles 1. 12J per crate.

The fruit of the second car was picked on Monday, July 12, and
was sold on Thursday morning, July 15. This car contained Elbertas
sprayed twice and Belles sprayed three times with the self-boiled
lime-sulphur; also unsprayed fruit of both varieties. The fruit of
this car brought the following prices :

Sprayed Elbertas $1. 45 per crate.

Unsprayed Elbertas 1. 25 per crate.

Sprayed Belles 1. 50 per crate.

Unsprayed Belles 1. 14 per crate.

In the first car the difference in favor of the sprayed fruit was 50
cents a crate for Elbertas and 12| cents a crate for Belles. In the
second car it was 20 cents a crate for Elbertas and 36 cents a crate for
Belles. An examination of several crates of Elbertas showed that 34
per cent of the unsprayed fruit was specked with brown-rot, while
only 6 per cent of the sprayed fruit was so affected. (See PL II.)
This difference in market value was due to the fact that the sprayed
fruit showed leas rot, was more highly colored, and had a better ap-

174

SPRAYING FOR CONTROL OF PEACH BROWN-ROT AND SCAB. 21

I j pearance in all respects than the unsprayed fruit. Another significant
fact is that in each case all the sprayed fruit was sold before the buyers
I began purchasing the unsprayed fruit, showing that they readily recog-
1 nized the superiority of the former. This marketing test indicates
i that the enhancement in the market value of sprayed fruit would
: pay the cost of the work several times over.

COST OF THE TREATMENT.

As previously stated, the spraying was done with a gasoline-power
outfit of 200-gallon capacity. Three men operating the machine
sprayed 900 to 1,000 trees a day. The mixture was prepared in
quantities of 32 pounds of lime and 32 pounds of sulphur in a barrel
with a small quantity of water, then strained into the spray tank or a
supply tank, and diluted to 200 gallons. When the blocks farthest
from the mixing platform were being sprayed, a 200-gallon supply
tank was used to haul the mixture to the spraying outfit so as to keep
the machine in operation and avoid delay as much as possible. One
man was required at the mixing station to prepare the mixture, but
his time was not entirely occupied in keeping the spraying outfit sup-
plied. In fact, one man should be able to prepare the mixture
rapidly enough for five or six spraying outfits.

The quantity of mixture required for each thousand trees varied
with the size of the trees. Medium-sized 7-year-old Elberta trees
required about 1,400 gallons per thousand for each application. To
make that quantity, 224 pounds of sulphur and the same weight of
lime were required . The block sprayed with arsenate of lead required
32 pounds of the poison in the first application (when the foliage was
scant) and 56 pounds in the second application for each thousand
trees.

The price of materials and labor used in the work at Fort Valley,
Ga., was as follows: Sulphur (flour), $2.85 per hundred pounds; lime,
$1.10 per barrel; arsenate of lead, 12 cents a pound; gasoline, 13 cents
a gallon; team (pair of mules), $2.75 a day; and labor, 75 cents a day.

At the above prices the cost of the self-boiled lime-sulphur treat-
ment was 1J to 1| cents per tree for each application, or an average
of 4^ cents per tree for three treatments. The combination lime-
sulphur-arsenate-of-lead treatment cost 5| cents per tree for four
applications. Where labor is higher and working hours shorter the
cost would of course be greater, but in the South, under conditions
similar to those existing at Fort Valley, it appears that the work can
be done at a cost of $15 per thousand trees for each application, or
$45 for three treatments. This cost is insignificant when considered
in connection with the fact that an increased yield of 25 to 50 per
cent, or in some cases 100 per cent, may be expected from the treat-
ment.

174

22 CONTROL OF PEACH BROWN-ROT AND SCAB.

DANGER OF INJURY TO THE FRUIT AND FOLIAGE.

If the self-boiled lime-sulphur is properly prepared and applied,
there is very little danger of injuring the fruit or foliage. In all of
our work during the past season not the slightest injury developed on
any of the several thousand trees sprayed. During the season the
writers examined several orchards, ranging from 200 to 500 acres, that
had been sprayed by the owners with self-boiled lime-sulphur. No
serious injury had resulted from the spraying in any of these orchards.
Where injuiy occurred at all, it was only slight and was confined to a
few dozen trees, except in one case where there was a general scorching
of the foliage throughout the orchard, due, perhaps, to too much boil-
ing of the mixture ; but even in this case the result was only a slight
thinning of the foliage, which was scarcely sufficient to damage the
trees. In each case the mixture was so exceedingly successful as a
fungicide that the owner did not consider the slight injury caused by
it as worthy of consideration. However, of the thousands of orchards
that will probably be sprayed with this mixture, there will doubtless
occur from time to time cases of rather serious injury. Such cases
in the opinion of the writers will be exceptional and will not be so
common or so serious as is Bordeaux injury of the apple.

It was expected that where arsenate of lead was used in these experi-
ments some injuiy might occur, but neither fruit nor foliage showed
any signs of injuiy. In the first application of poison made when the
dried calyces were shedding, no lime-sulphur was used, but in the
second, three weeks later, the lime-sulphur mixture and arsenate of
lead were used in combination. It seems barely possible that the
lime-sulphur preparation may correct the tendency of the arsenate
of lead to injure, although no definite evidence on this point has yet
been obtained. In the experiments conducted at Marshallville, Ga.,
last year, peach foliage and fruit spiked with the self-boiled wash and
arsenate of lead combined were slightly injured," but the notes on
this work indicate that the injury was.due mostly to the lime-sulphur
wash, which was boiled too long in an effort to get a large amount of
sulphur in solution. Some arsenate-of-lead injury will doubtless
occur from time to time, but where the curculio is so bad, as in
southern peach orchards, it would seem advisable for the owners to
take some risk in the use of the poison to hold this insect in check.

DANGER OF STAINING THE FRUIT.

There is some danger of staining the fruit with the mixture if it is
applied within two or three weeks of the ripening period. Mr. C. A.
McCue,6 of the Delaware experiment station, reported good results

a Circular 27, Bureau of Plant Industry, U. S. Dept. of Agriculture, pp. 6-7.

b Bulletin 85, Delaware Agricultural Experiment Station.

174

SPRAYING FOE CONTROL OF PEACH BROWN-ROT AND SCAB. 23

against brown-rot from the use of self-boiled lime-sulphur during
1908, but complained of marring the appearance of the fruit by
heavy deposits of lime. The formula that he used (15 pounds of
lime and 10 pounds of sulphur to 50 gallons of water) was stronger
than necessary, and the spraying was perhaps continued too near the
•ripening period. In our 1907 experiments this heavy mixture was
used and at picking time the fruit was somewhat stained, but the
amount of lime used has since been reduced from 15 to 8 pounds
in 50 gallons and the staining now is not a serious matter. The
Chicago buyers who purchased the sprayed fruit of the orchard
at Xeoga. 111., in which our 1908 experiments were conducted, made
no complaint of staining, but on the contrary declined to purchase
any of the unsprayed fruit on account of bad scab infections. The
sprayed fruit of the Georgia experiments showed evidence of the
mixture at picking time, but the whitish specks were largely rubbed
off in picking, sorting, and packing. It was more highly colored,
slightly larger, and presented a much better appearance than the
unsprayed fruit. However, in order to avoid whitewashing the
fruit, the last application should be made not later than about
four weeks before the ripening period and care should be taken to
give the peaches a uniformly light coating of fine spray.

RESULTS OBTAINED BY GROWERS IX COMMERCIAL ORCHARDS.

A considerable number of peach growers have already taken up
the self-boiled lime-sulphur treatment for the control of scab and
brown-rot. and the writers have been able to obtain reports from some
of these. Stranahan Brothers, of Bullochville. Ga.. were among

7 7 7 O

the first to give it a trial on a commercial scale. In 1908 they
sprayed their orchard of 35,000 trees twice with self-boiled lime-
sulphur and arsenate of lead. In a letter dated January 13, 1909,
they report that, aside from about 50 trees, the leaves of which were
slightly burned, "not a leaf or peach was injured and we had no
brown-rot and only one-half of 1 per cent of wormy peaches, including
culls and drops. In fact, we had no drops, May, June, or otherwise,
and had to thin the fruit three time-.'- They sprayed the orchard
again in 1909, using about the same treatment, and the junior writer
made observations on the results at two different times during the
season. It was found that considerable injury to foliage had occurred
at several places in the orchard, due perhaps to too much cooking of
certain lots, but in no case did this injury appear to be serious, cer-
tainly not sufficient to discourage spraying. Peach scab and brown-
rot were almost completely controlled, as was the case the previous
year.

Miller Brothers, of Okonoko. W. Va., were as quick to take up the
treatment, and their work was directed more especially to the control

174

24 CONTROL OF PEACH BROWN-ROT AND SCAB.

of peach scab. They sprayed their orchard of 600 acres in 1908 and
again in 1909 and report that they obtained good results both sea-
sons. In previous years the scab had been so bad that a large
percentage of the crop was lost each year, and the owners con-
sidered the orchard unprofitable until the lime-sulphur treatment
made possible the control of this disease without injury to the
foliage.

During 1908 the Sleepy Creek Orchard Company, of Sleepy Creek,
W. Va., sprayed their orchard of 15,000 peach trees from three to six!
weeks after the petals fell with 8-8-50 self-boiled lime-sulphur. A
portion of the orchard was sprayed again a month later. Fortunately
in this orchard trees were left unsprayed as checks and the difference
between the sprayed and unsprayed fruit was so striking that the
writers deemed it worth while to sort the fruit from several trees and
obtain exact percentages of scab infections. From an Elberta
tree sprayed twice there were 1,551 peaches, 15 per cent of which
was slightly affected with scab and none badly scabbed. Another
Elberta tree sprayed only once had 731 peaches, 44 per cent of which
showed some scab spots, but only 1.3 per cent was badly scabbed.
(See PL IV, fig. 1.) An unsprayed tree in the check block had 468
peaches, all of which were affected and 86 per cent badly scabbed.
(See PL III, fig. 2, and PL IV, fig. 2.) These three trees selected
for this count work were situated close together in a rather low place
where the scab would naturally be bad. It will be observed that one
spraying held the disease in check, so that only a little more than 1
per cent of the crop was badly affected, while 86 per cent of the un-
sprayed fruit came in this class. However, it would not be wise to
conclude from this that one application is sufficient. It is shown that
44 per cent of the fruit sprayed once had some scab infections. The
second application reduced this to 15 per cent, none of which was bad.
In other words, all of the fruit from the trees sprayed twice was
suitable for packing, and none of it had enough scab to attract atten-
tion; all but 1 per cent of the fruit from the trees sprayed once was
suitable for packing, but had enough scab infections to detract
somewhat from its appearance, while 86 per cent of the fruit from
the unsprayed trees was entirely unsuited for the market and the
remainder was sufficiently affected to decrease its market value.

COURSE OF TREATMENT RECOMMENDED.

Self-boiled lime-sulphur, when properly applied, will entirely con-
trol peach scab, and when the curculio does not interfere too seri-
ously it will largely prevent brown-rot. In view of the fact that
numerous brown-rot infections take place through curculio punctures,
it would seem advisable, where the two troubles occur together, to
use arsenate of lead in connection with the lime-sulphur mixture as a

174

COURSE OF TREATMENT RECOMMENDED. 25

, combined remedy for both troubles. The fact that arsenate of lead
sometimes injures both the fruit and the foliage of the peach is well
known and should be borne in mind by the orchardist, but when
the applications are made early in the season the danger of injury
seems to be slight. Therefore, upon the advice of Mr. A. L. Quaint-
ance, of the Bureau of Entomology, arsenate of lead is included in the
course of treatment outlined below.

BROWN-ROT, SCAB, AND CURCULIO TREATMENTS

For the Elberta, Belle, Reeves, and other varieties of peaches of
about the same ripening season, the following is advised:

(1) About the time the calyces (or shucks) are shedding, spray with arsenate of lead
at the rate of 2 pounds to 50 gallons of water. In order to reduce the caustic prop-
erties of the poison, add milk of lime made from slaking 2 pounds of stone lime.
The date of this treatment is too early for scab and ordinarily no serious outbreaks of
brown-rot occur so early, so that the lime-sulphur may be omitted with reasonable
safety; but during warm rainy springs, especially in the South, the lime-sulphur will
doubtless be necessary in this application.

(2) Two to three weeks later, or about one month after the petals drop, spray with
8-8-50 self-boiled lime-sulphur and 2 pounds of arsenate of lead.

(3) About one month before the fruit ripens spray with 8-8-50 self-boiled lime-
sulphur, omitting the poison.

For earlier maturing varieties, such as Waddell, Carman, and Hiley,
the first two treatments outlined above would probably be sufficient
ordinarily, but in very wet seasons bad-rotting varieties would doubt-
less require three treatments. Late varieties, such as Smock and
Salway, having a longer season, would not be thoroughly protected
by three applications, but on account of the expense the writers
dislike to recommend a fourth spraying. In view of the results
obtained on mid-season varieties it seems likely that three treatments
i will ordinarily be sufficient for the late varieties.

« The attention of the reader is called to the following statement by Mr. Quaintance
i regarding the use of arsenate of lead on the peach for the control of the curculio:

"The schedule of applications, arranged to effect a combination treatment for the
i plum curculio and brown-rot, represents a compromise as to the number of applica-
i tions and times of spraying considered strictly from the curculio standpoint. Thus,
were the control of the curculio the only consideration, the first application should
be made within a week after the falling of the petals; the second about as the dried
calyces, or "shucks," are being thrown off by the rapidly swelling fruit, and a third
about two weeks later, though this latter treatment is attended with increased risk
to the foliage and fruit.

"Of the several arsenical poisons, arsenate of lead should always be employed for
stone fruits, especially the peach. There are now numerous brands of arsenate of
lead on the market, and while most of these are carefully prepared and ordinarily
free from dangerous by-products the grower should exercise care in the selection of
a brand, purchasing only from reputable firms. Arsenical injury to peaches mani-
fests itself by a shot-holing and dropping of the leaves and an excessive reddening
and sometimes falling of the fruit as it approaches maturity. The extent of inj un-
liable to result will depend upon weather conditions, and the number of applica-
tions given. Ordinarily, the risk from two applications of arsenale of lead, as out-
lined for use with the lime-sulphur mixture, will be inconsequential, and the
orchardist can well afford to take the chances of injury in view of the great benefit
derived in lessening brown-rot and in the control of the curculio itself."
174

26 CONTROL OF PEACH BROWN-ROT AND SCAB.

BROWN-ROT AND SCAB TREATMENT.

In orchards where curculio is not troublesome, the arsenate of lea(
should be omitted. The treatment for brown-rot and scab on mid-'
season varieties would then be as follows :

(1) Three to four weeks after the petals fall spray with 8-8-50 self-boiled lime-
sulphur.

(2) About three weeks later spray with the same mixture.

(3) About one month before the fruit is expected to ripen make another applica-
tion of the same mixture.

SCAB TREATMENT.

For the treatment of scab alone, spray the trees with 8-8-50 self-
boiled lime-sulphur about one month after the petals drop andl
again three to four weeks later.

One treatment thoroughly applied one month after the petals drop
will so nearly control scab that in many cases a second spraying
may not be necessary, but on account of the way spraying is ordi-l
narily done two treatments will usually be required, especially on
late varieties.

APPLICATION OF THE SPRAYING MIXTURES.

The necessity of keeping the mixtures thoroughly agitated while
spraying can not be too strongly emphasized. Both self-boiled lime-
sulphur and arsenate of lead settle readily, and if the spraying outfit
is not equipped with a good agitator the mixture will not be evenly
distributed and some of the trees will be oversprayed, while others
will receive an insufficient application. In power sprayers the pro-
peller type of agitator is the most satisfactory for this work. The
early applications of lime-sulphur may be made rather heavy, but
the last spraying should be made with fine nozzles, and the aim
should be to give the fruit a uniform coating of a mist-like spray.
Heavy drenching of the trees should be avoided.

174

PLATES

174

27

DESCRIPTION OF PLATES.

Plate I. Frontispiece. Peaches affected with brown-rot, showing the destructive
work of the disease, the rotten, moldy appearance of affected peaches, and the
gray tufts of spores produced by the fungus. This is a photograph of a pile o:
discarded Carman peaches in an orchard at Fort Valley, Ga.

Plate II. Two crates of Elberta peaches picked from the experimental plats at Fort
Valley, Ga., on July 9, 1909, shipped by refrigerator car to New York, and the:
by express to Washington, D. C, opened and photographed on July 16, a week
after picking, showing the difference in the amount of brown-rot developed . The
fruit on the left was from a sprayed plat, No. 6, and developed very little brown-
rot, while that on the right was from an adjacent unsprayed plat and became
badly affected with brown-rot in transit.

Plate III. Peach scab. Fig. 1. — Two unsprayed Elberta peaches affected with
scab, showing the black spots and cracks produced by the fungus. Fig. 2. — The
crop of peaches from an unsprayed Elberta tree, showing the fruit badly affect
with scab. All the fruit was affected and 86 per cent of it was so "smutty " an
cracked as to be unfit for the market. This fruit was from one of the unsprayed
trees in the orchard of the Sleepy Creek Orchard Company, at Sleepy Creek,
W. Va.

Plate IV. Peach scab. Fig. 1. — The crop of peaches from an Elberta tree sprayed
once with self-boiled lime-sulphur. The good, merchantable fruit (98 per cent
of the crop) is shown in the pile and the unmerchantable, scabby fruit on the
notebook at the top. This fruit was grown in the same orchard as that shown in
Plate III, figure 2. Fig. 2. — The same unsprayed crop shown in Plate III, figure 2,
sorted for the market. The large pile of fruit on the right is unmerchantable on
account of scab, that on the left representing all that was suitable or packing
(only 14 per cent of the crop).
174
28

Bui. 174, Bureau of Plant Industry, U. S. Dept. of Agriculture.

Plate II.

I, E I ~ "d'jst7 U. S. Dept. :; f\gr cu lure

Plate III.

Fig. 1 .— Two Unsfrayed Elberta Peaches Affected with Scab, Showing the
Black Spots and Cracks Produced by the Disease.

Fig. 2.— Crop from an Unsprayed Elberta Peach Tree, Showing All the Fruit
Affected with Scab and 86 Per Cent of It Unmerchantable. Sleepy Creek.
W. Va., August 27, 1909.

PEACH SCAB.

5. 174, Bureau of Plant Industry. U. S. Dept. of Agriculture.

Plate IV.

Fig. 1.— Crop of Elberta Peaches from a Tree Sprayed Once with Self-Boiled
Lime-Sulphur. Good, Merchantable Fruit in the Pile and Unmerchantable,
Scabby Fruit on the Notebook at the Top. Sleepy Creek, W. Va., August 27,
1909.

Fig. 2.— The Same Unsprayed Crop Shown in Plate III, Figure 2, Sorted for the
Market. The Large Pile on the Right is Unmerchantable, Scabby Fruit, that
on the Left Representing All that was Suitable for Packing.

PEACH SCAB.

INDEX

Fajre.

Agitator, use in application of self-boiled lime-sulphur 26

Arsenate of lead. See Lead, arsenate.

Ascospores, brown-rot, peach infection 1 1>

Belle peach, disease control, treatment recommended 25

sprayed compared with unsprayed fruit, marketing tests 20-21

spraying, experiments 20-21

Black-spot, peach. See Scab, peach.

Bordeaux mixture, spraying for control of peach brown-rot not successful 9

Brown-rot, ascospores, peach infection 12

caused by Sclerotinia fructigena 8

control, spraying, description of outfit 15

experiments in several States 7-8

with Bordeaux mixture 9

self-boiled lime-sulphur, effect of single ap-
plication 17

experiments 14-24

study of hygienic measures 9

treatment recommended 24-26

use of arsenate of lead with self-boiled lime-sulphur, ex-
periments t. 18-20

cooperative studies of infections on sprayed fruits 13

damage and loss to fruit shippers and consumers 10-11

destructiveness 9-11

distribution in United States 9-10

economic importance 9-11

fungus, life history 11-12

history 8-9

influence of weather on growth of fungus 12-13

loss to peach growers of United States 9

various States 9-10

nature, cause, and combative methods 11-12

responsible for fruit inspection in New York 10-1 1

spores, spreading, influence of insects 13

Carman peach, disease control, treatment recommended 25

Cladosporium carpophilum, fungus causing peach scab, description, control

methods, etc 13-14

Curculio, control, experiments 18-20

treatment recommended 24-26

influence in spreading peach brown-rot 13, 16-17

Elberta peach, brown-rot and scab, control in West Virginia, experiments 23-24

disease control, treatment recommended 25

sprayed compared with unsprayed fruit, marketing tests 20-2 1

spraying for brown-rot and scab, experiments with self-boiled

lime-sulphur 18-21

174 29

30 CONTROL OF PEACH BROWN-ROT AND SCAB.

Page.

Foliage, peach, susceptibility to injury by fungicides 7

Freckles. See Scab, peach.

Fruit, sprayed, market value, comparison with unsprayed fruit 16-17

Fungicide, development, experiments by Bureau of Plant Industry 7-8

Fungicides, copper, injury to peach foliage 7

Fungus causing brown-rot, life history 11-12

Georgia, peach-tree disease, control, spraying experiments 14-24

enemies, treatment with self-boiled lime-sulphur and arse-
nate of lead 18-20

Hiley peach, disease control, treatment recommended 25

Insects, influence in spreading spores of brown-rot 13

Introduction to bulletin 7-8

Lead, arsenate, use with self-boiled lime-sulphur for control of curculio 18-20

peach brown - rot

and scab 18-20

Lime-sulphur, self-boiled, directions for preparation 15-16

spraying peach trees, control of brown-rot and scab,

experiments 14-24

cost 21

danger in use 22-23

effect of single application 17

on yield 18

experiments 16-18

method of application 26

value as fungicide 7-8

use with arsenate of lead for control of curculio 18-20

peach brown-
rot and scab 18-20
Mixture, Bordeaux. See Bordeaux mixture.

Monilia fructigena, imperfect form of brown-rot fungus 8

Peach, Belle, disease control, treatment recommended 25

sprayed compared with unsprayed fruit, marketing tests 20-21

spraying, experiments 20-21

black-spot. See Scab, peach,
brown-rot. See Brown-rot.

Carman, disease control, treatment recommended 25

curculio, control, experiments 18-20

Elberta, brown-rot and scab, control in West Virginia, experiments 23-24

disease control, treatment recommended ^ 25

sprayed compared with unsprayed fruit, marketing tests 20-21

spraying for brown-rot and scab, experiments with self-boiled

lime-sulphur 18-21

foliage, injury by use of fungicides 7

fruit and foliage, danger of injury from use of self-boiled lime-sulphur. 22

danger of staining by spraying with self-boiled lime-sulphur 22-23

Hiley, disease control, treatment recommended 25

orchards, spraying, description of outfit 15

Reeves, disease control, treatment recommended 25

Salway, disease control, treatment recommended 25

scab. See Scab, peach.

Smock, disease control, treatment recommended 25

spraying, comparison of crop with that from unsprayed trees 16-17

with self-boiled lime-sulphur, benefits 7-8

cost 21

174

IXDEX. 31

Page.

Peach. Waddell, disease control, treatment recommended 25

spraying experiments 16-18

Peaches, yield, effect of spraying with self-boiled lime-sulphur 18

Reeves peach, disease control, treatment recommended 25

Rot, brown. See Brown-rot.

Salway peach, disease control, treatment recommended 25

Scab, peach, caused by fungus Cladosporium carpophilum 13-14

character, importance, and methods of control 13-14

control, spraying, description of outfit 15

with self-boiled lime-sulphur, effect of single

application. . . 17

experiments 14-24

treatment recommended 24-26

use of arsenate of lead with self-boiled lime-sulphur, ex-
periments 18-20

distribution and damaging effects 14

prevention by use of self-boiled lime-sulphur 7-8

Sclerotinia fructigena, fungus causing peach brown-rot 8

occurrence in foreign countries and United States 8-9

Smock peach, disease control, treatment recommended 25

Spores, brown-rot, influence of insects in spreading 13

Spray, self-boiled lime-sulphur, value for peach trees 7-8

Spraying, peach, comparison of crop with that from unsprayed trees 16-17

control of brown-rot and scab, experiments 14-24

description of outfit 15

single application of self-boiled lime-sulphur, tests 17

with self-boiled lime-sulphur, cost 21

Torula fructigena, origin of name and classification by botanists 8

Waddell peach, disease control, treatment recommended 25

spraying experiments 16-18

174

o

I

[Continued from page 2 of cover.]

No. 89. Wild Medicinal Plants of the United States. 1906. Price, 5 cents.

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174