Circular [Feb. 1921]

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Georgia

State Board of Entomology

A. C. LEWIS, State Entomologist, Atlanta, Ga.

CIRCULAR 34

FEBRUARY, 1921

CONTROL OF CURCULIO AND BROWN ROT OF

PEACHES

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A. State

By C. LEWIS, Entomologist

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W. W. CHASE,

Assistant State Entomologist.

Curculio and brown rot destroyed millions of dollars worth of peaches in Georgia in 1920. To avoid similar damage this year, the peach growers must use every means at their command to control the curculio and brown rot. Spraying alone must not be relied upon to control these troubles this year.
The following spraying and dusting schedules are recommended for 1921 by the Georgia State Board of Entomology and the U. S. Bureau of Entomology. The schedules are based upon experiments conducted by the Georgia State Board of Entomology for the last ten years, and upon similar work of the agents of the U. S. Bureau of Entomology in Georgia and elsewhere. These schedules are the best that can now be recommended from our present information upon the life history of the curculio and brown rot, and are thus intended to meet the emergency that exists at present. Furher studies in the life history of the curculio and spraying and dusting experiments for the control of curculio and brown rot may enable us in another year to offer more effective spraying and dusting schedules.
Peach growers are advised that the soluion of this brown rot question rests largely with the way in which they, as individuals, meet it. If they are willing to study and give the time and attention necessary to insure careful and timely application of sprays, and personal attention to the other details as outlined, the fight against brown rot and curculio can be won successfully and profitably. If matters are allowed to rock along as here>tofore and use is not made of other and unusual weapons all the odds are in favor of a recurrence of last season's disappointment and losses.
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SPRAY SCHEDULE FOR LATE PEACHES-1921.

Time of Application.

Material to Use.

1-Apply as soon as calyces 1 lb. powdered arsenate of

begin to split, being sure lead; 3 lbs. lime to 50 gallons

to complete the spraying of water.

by the time the calyces

have all shed. In case of

large acreage the spraying should be planned so as to

complete the application of poison by the time the fruit

is exposed.

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If acreage is small the application may be delayed

until calyces start to shed, provided spra)Qng them eau

be completed by the time calyces are all off.

2-Apply two to three weeks lIb. powdQred arsenate of

after first spraying.

lead and self boileli lime sul-

phur 8-8-50; or atomic sul-

phur 3 to 4 lbs. 2 lbs. lime

as to 50 gallons water.
3-Apply one month before Same formula second

fruit ripens.

spraying.

4-Ten to 14 days before Self boiled lime sulphur

fruit ripens, if Brown

(8-8-50); or atomic

Rot appears and rains are sulphur 3 to 4 lbs.. 2 lbs. lime

frequent.

to 50 gallons water.

DUST SCHEDULE FOR LATE PEACHES-1921.

Use the following formnla Arsenate of lead 5%,

t=hrol5lvlhbso.uat rtsheenasteeasoofnl:ead.

Sulphur

80%, :: 80 lbs. sulphur.

Lime

15%, :: 15 lbs. lime, to 100 lbs.

of mixture.

Four applications to be applied at the same time and

periods as in spray schedule. except in the first dusting be-

gin a few days later. Fourth application optional,-if trees

and fruit show no injury, and brown rot appears and rains

are frequent.

SPRAYING AND DUSTING SCHEDBLES FOR EARLY

VARIETIES-1921.

Spray or dust the early varieties from 2 to 3 times. Use

formulas 1 and 2, or 1. 2 and 4. Apply same time as first,

second and fourth applications in above schedule.

NOTE: Peach foliage and fruit may show some in;ury

from three applications of arsenate of lead 1 lb. to 50 gallons

of water if there are frequent rains. Injury will be more pro-

nounced on older trees or those on thin soil, or in a weak-

ened condition. Vigorous trees on strong soil are least

likely to suffer. If after the second spraying much injury

shows up, the amount of arsenate of lead in the third spray-

ing might be reduced to % of a pound to 50 gallons of water.

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BROWN ROT IN RELATION T() CURCULIO.
As praetically every brown rot infection of the peach enters through curculio egg or feeding punctures or other breaks in the skin, it follows that the control of the curculio is essential in order to reduce the amount of brown rot. In experiments conducted by this department, where the curculio was controlled effectively, brown rot was also controlled very satisfactorily.
NITROGEN IN RELATION TO BROWN ROT.
The tendency of peaches to rot is closely identified with the amount and densi.ty of shade and supply of moisture present. Hence, fertilization plays a prominent part in the brown rot problem. The more nitrogen a tree is fed, the more wood and leaves it produces, the more shaded the fruit and the sappier and softer the growth of the wood. and also probably the fruit. These make ideal conditions for the development of brown rot. Where these conditions prevail the temporary abandonment of all forms of nitrogenous fertilizers for at least one season and the substitution of potash would each serve in its own way towards the mending of a very bad situation-so' bad that it actually threatens the very life of the Georgia peach industry.
PRUNING..
Sunshine is one of the best fungicides and germicides we have, and a powerful ally to the spray nozzle. It is also the best fruit coloring agent, and it's free. It follows from this that peach trees should be pruned so as to let in the sunshine. By the intelligent use of the open or vase-shaped type of pruning, sunshine may be admitted to all parts of the tree and spraying be more effectively and economically accomplished.
THE NECESSITY FOR MORE THOROUGH SPRAYING.
The crying demand of the present deplorable situation is for more thorough aud better quality of spraying, both winter and summer, than that which at present obtains in the average orchard. Spraying is a job calling for good eq~ipment, for thoroughness rather than haste. Here is one of, the points at which the orchardist should be in close touch with the actual carrying 'out of the work.
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SUMMARY AND SUGGESTIONS.

Summarizing the suggestions as outlined in the preced-

ing paragraphs, the steps that should be taken in the order

named are as follows:

1-After the leaves have shed, prune off diseased limbs .

and twigs and open up the center of the trees by removing

all the smaller limbs that tend to close it up and prevent the

entrance of sunshine and the free circulation of air.

2-Following the pruning every tree should be 100%

sprayed with the lime sulphur solution. Let the appear-

ance of the trees after drying be your witness. If there are

areas of bark not covered by the spray don't expect too

much of the job. If dry lime sulphur, soluble sulphur, or

r.

similar proprietary substances are used do not expect them

to do more than the manufacturers claim they will do, on

the package. To secure effective control of the San Jose

scale these preparations should be used somewhat stronger

than recommended by the manufacturers.

3-Early in the fall as possible clean up by burning all

trash and rubbish around the orchards. To secure the best

results this should be done by the first of November.

4-Practice frequent and shallow cultivation under the

trees every two weeks during the months of May, June and

July to destroy the pupre of the curculio before they mature.

5-Spray during the summer as recommended on page

2. Remember when spraying during the summer that you

are spraying to protect the fruit. Hence see to it that the

peaches are covered all over with a fine mist. When dust-

ing, dust only one row at a time. If possible apply the sec-

ond application of dust to the other side of the trees.

6-Following the harvest of the first ripening variety

this season, immediately remove and destroy all fallen

peaches and those left on the trees. So with each successive

variety. To be effective this work must be done within a

week after the final picking of the variety. inasmuch as the

larvre in the fallen fruit will emerge and enter the soil to

pupate within seven to ten days. The peaches thus gathered

should be hauled to ditche.s or gullies and covered by 24

inches of soil to prevent the emergence of the beetles, or

mixed with and covered by quick lime and wetted to kill the

larvre in the fruit by heat. If this measure of prevention is

undertaken promptly and thoroughly, literally millions of

larvre will be destroyed before reaching the beetle stage.

7-Forego temporarily the use of nitrogenous fertilizers,

the planting of peas and other legumes except where the

condition of the trees demands them. If fertilizer is ap-

plied, use pOtash.

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