Title: Pecan insect and disease recommendations
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Title: Pecan insect and disease recommendations
Physical Description: Book
Creator: French, W. J.
Publisher: Agricultural Research Center, Agricultural Experiment Station, IFAS, University of Florida
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Bibliographic ID: UF00076498
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AirL AGRICULTURAL RESEARCH CENTER MONTICELLO
I AGRICULTURAL EXPERIMENT STATION IFAS
UNIVERSITY OF FLORIDA GAINESVILLE, FLORIDA

Research Report BB 1980-2 January 31, 1980
REVISED

PECAN INSECT AND DISEASE RECOMMENDATI NS"IIL i.JBR
W. J. French and J. C. Ball 1,2


Disease and insects are often the limiting factors i'ni~h roui1Dti~QK pforida
pecans in Florida. The nut requires about 7 months to deveTop a~dur ur- g-tha---
time is subject to attack by a variety of pests. A good disease and insect con-
trol program is important, not only in protecting the maturing crop, but it is
essential to the production of high yields year after year. Trees which are
prematurely defoliated by insects, mites, and diseases frequently set a light
crop the following year. Pecan varieties differ in resistance to scab and other
diseases. Scab susceptible varieties will require more fungicides sprays than
resistant varieties. Check with your county extension director to determine the
most suitable varieties for local conditions. Although today's pecan grower is
fortunate to have effective fungicides, insecticides, and improved spray,equip-
ment available to him, spraying for pest control is not an easy job. It requires
attention to many details that on the surface may seem unimportant. Even the best
* spray program can be improved if the following cultural and sanitary practices are
followed:
1. Knock shuck from branches. Turn under, or rake and burn, culls,
shucks, leaves and leaf stems, to prevent build-up of insects and
diseases. For shuckworm control, disc 3 inches deep during late
February or early March.
2. Provide better air circulation in orchard; mow or disc weeds, and
prune low hanging limbs. Keeping the tree row weed-free by use of
herbicides is recommended.
3. Maintain tree vigor by following recommended fertility practices.
(See Circular 280-B, Pecan Production in Florida.)

Perhaps the three most important factors in a spray program are timing, coverage
and rate.
Timing Pecan disease, such as scab, must be prevented by providing a protec-
tive covering of fungicide over all susceptible tissue from the time the first
leaves unfold until the nut is developed. If the disease becomes established on
young foliage it is more difficult to prevent infection on the nuts during the
remainder of the season. Some insects such as nut casebearer, pecan weevil, and
hickory shuckworm occur in orchards at particular and somewhat predictable times.
Timing of sprays for control of these insects is very important and each grower
should learn to recognize the vulnerable stages of these insects and time his

1 Assoc. Plant Pathologist and Asst. Entomologist.
2 Prepared in collaboration with G. Simone, Extension Plant Pathologist, and
J. E. Brogdon, Extension Entomologist.









sprays accordingly. The pecan weevil is becoming a serious pest of pecans in
Florida. The adults emerge from the soil beginning in July and can continue emer-
gence into November. Adults feed on the nuts until the shell begins to harden and
then they commence to lay eggs. Feeding prior to shell hardening prevents nut
development and causes the nut to drop. Growers should check for adult weevils
starting about July 1 by shaking branches, using traps (sticky bands, burlap bands,
ground cages), or spraying a few selected trees with a quick knock down spray such
as pyrenone (lay a ground cloth under the trees so that the dislodged weevils can
be seen). Spray when adult weevils are found and continue at 7 to 10 day inter-
vals during weevil emergence. Spraying need not start until the shell begins to
harden, if the early population does not appear large enough to cause serious nut
drop. Excessive use of insecticides should be avoided as it may create insect
problems that otherwise would not exist, as well as adding to the pollution of
our environment.

Coverage In applying spray materials, all leaves, twigs, and nuts should
be covered. Hydraulic machines are designed to use large volumes of water to
carry the chemicals to the trees. Sprays should be applied until water runs off
leaves in the upper portion of the tree. Do not attempt to concentrate or use
low volume sprays with hydraulic equipment (Table II). Air blast and mist blowers
are designed for low volume applications. Air blast equipment should be adjusted
before the spray season begins to deliver the desired volume of spray in the
proper pattern as is dictated by tree size. Consult instruction manuals or spray
machine representative for advice on correct placement of spray nozzles. Remember,
when spraying with air blast sprayers, the pesticide is carried to the tree in a
small volume of water which is diluted by a larger volume of air. Too fast a rate
of travel will result in insufficient coverage where the trees are not filled with
spray-laden air. Rate of travel should not exceed 2.5 miles per hour. A machine
with too small an air capacity will not replace the air contained in the tree with
spray-laden air, thus poor coverage results. Small to medium sized trees can be
row sprayed while very large trees should be circled.

Rates Fungicides and insecticides are recommended at specific rates of
application which have been found to be effective and non-phytotoxic under Florida
conditions. It is, therefore, very important to: 1. Know required rate of chemi-
cal per tree; 2. Calculate the gallons of spray per tree the machine will deliver
at a given rate of travel; 3. Calculate the amount of chemical to add per tank.
Example: DuTer is recommended at 0.08 pound of 47.5% formulation per tree. If
10 trees are sprayed per 100 gallons of water, then 10 times 0.08 equals 0.8 pound
of DuTer required per 100 gallons or 4 pounds per 500 gallon tank.

The following spray schedule (Table I) will give commercial control of impor-
tant disease and insect pests. The schedule is designed for scab susceptible
varieties. Scab resistant varieties are susceptible to other leaf spot diseases
and should be sprayed with fungicides two or three times during the summer. Where
rosette is present, use a spray of neutral zinc (2 pounds) or zinc sulphate (2
pounds of 65%). Zinc sulphate is very corrosive and will rust machinery. It must
be washed out with soap and water after use. Foliar nutrient sprays should be
applied separately, and not mixed with fungicides or insecticides, unless compati-
bility is known. If uncertain, consult label and compatibility charts.

The insecticides listed in this guide have been shown in field trials to be
effective against the pests; however, because of local differences in use patterns,








ie. frequency of application, pesticide used, etc. some materials may no longer
* be effective or they may cause upsets of other pests. Alternating materials should
help to avoid or delay these problems as will the practice of spraying only when
necessary. In any event, the grower should be aware of this and be prepared to
shift materials as the situation demands.


PRECAUTIONS

Parathion, Guthion, Systox and Torak are especially toxic to man and should
be applied only by properly trained and equipped operators. Read the entire label
before opening any pesticide container and heed all cautions and warnings. Store
pesticides in original labeled containers and out of reach of children, pets, and
livestock, under lock and key. Dispose of left-over spray materials and all empty
containers promptly and safely. Follow the recommended dosage and waiting periods
to avoid excess residues and injury to plants and animals. Avoid drift of pesti-
cides to adjacent areas. See Table IV on Residue Tolerances.

In order to avoid developing benlate resistant strains of scab, Benlate should
be alternated with either Duter or Cyprex throughout the season.

NOTE

This schedule is a guide to aid the grower; however, all pertinent information
relating to the pesticides cannot be included. It is the responsibility of the
grower to read the label for information on restrictions and correct use. Use of
is a pesticide inconsistent with the label is illegal.


TABLE I

PECAN SPRAY SCHEDULE FOR SCAB SUSCEPTIBLE VARIETIES1


SPRAY TIME OF APPLICATION
NO. (Approx. date for
north Florida)


PEST TO
CONTROL


SPRAY MATERIAL
(For rates, see
Table III.)


1. 1st prepollination Scab DuTer, Cyprex or Do not use Cyprex on Moore or
spray: When leaves Benlate Van Deman Var. Do not graze
first show green, livestock in treated groves
Leaf and 1. Parathion or except where Malathion, and/or
Approx. April 1 nut case- 2. Guthion or Benlate are used. (If a spray
bearer. 3. Malathion or program was not followed for
4. Torak the last few years, over-
wintering leaf and nut case-
bearers may be a problem and
require treatment.)


2. 2nd prepollination
spray: When leaves
are half grown.

Approx. April 15


Scab

Downy spot


DuTer, Cyprex or
Benlate


Nursery
blight


Increase gallonage per tree as
the foliage grows. Wettable
powders such as DuTer are some-
times physically incompatible
with emulsifiable concentrates.
Check compatibility of DuTer
with EC insecticides before
mixing large amounts.


For scab-resistant varieties, delete fungicide from all but sprays No. 3 and 6.
For scab-resistant varieties, delete fungicide from all but sprays No. 3 and 6.


REMARKS









TABLE I continued

PECAN SPRAY SCHEDULE FOR SCAB SUSCEPTIBLE VARIETIES


SPRAY TIME OF APPLICATION
NO. (Approx. date for
north Florida)


PEST TO
CONTROL


SPRAY MATERIAL
(For rates, see
Table III.)


3. 1st cover spray:
When nuts are 4"
long.

Approx. May 1


Scab,
Powdery
mildew

Leaf and
nut case-
bearer


Aphids,
Mites


DuTer, Cyprex or
Benlate


1. Parathion or
2. Guthion or
3. Malathion or
4. Zolone or
5. Torak

Dimethoate,
Systox or any of
above


Proper timing for nut casebearer
is very important. If 1st
prepollination insecticide was
applied for leaf and nut case-
bearer control, it is not
necessary to repeat this spray.


Spray for aphids or mites if
they appear to be on the in-
crease.


4. 2nd cover spray: Scab See first cover If weather is rainy, apply
Three weeks Powdery spray fungicide at two-week intervals
after No. 3. mildew or increase rates by .
Aphids
Approx. May 21 Mites

5. 3rd cover spray: Scab See first cover Begin checking small nuts for
Three weeks Downy spot spray. shuckworm damage. If present,
after No. 4. Brown leaf apply Guthion, Zolone or
spot Parathion.
Approx. mid-June Powdery
mildew
Aphids
Mites

6. 4th cover spray: Scab Apply second and third shuck-
First or second Downy spot worm sprays at two week inter-
week in July. Brown leaf vals.
spot
Powdery See first cover
mildew spray.
Aphids
Mites

Shuckworm Guthion, Zolone,
Torak or Parathion.
Pecan See section on Timing.
Weevil Sevin


REMARKS








TABLE I continued

PECAN SPRAY SCHEDULE FOR SCAB SUSCEPTIBLE VARIETIES


SPRAY TIME OF APPLICATION
NO. (Approx. date for
north Florida)


PEST TO
CONTROL


SPRAY MATERIAL
(For rates, see
Table III.)


7. 5th cover spray:
Last week in July
or first week in
August.


Scab
Downy spot
Brown leaf
spot
Powdery
mildew
Aphids
Mites

Shuckworm
Pecan
weevils


See first cover
spray.


See 4th cover
spray.


8. 6th cover spray:
Mid-August to
1st week in Sept.


Scab
Downy spot
Brown leaf
spot
Powdery
mildew
Mites

Shuckworm
Pecan
weevil

Black aphid


See first cover
spray.


Do not apply after shucks start
to open. If rainy weather con-
ditions exist, it may be neces-
sary to apply 7th cover spray.


See 4th cover
spray.


Dimethoate, Systox,
Torak or Zolone


TABLE II

GALLONS OF SPRAY BY TREE SIZE

TYPE OF EQUIPMENT GALLONS OF SPRAY BY TREE SIZE
Small Medium Large
(Under 25 feet) (25-35 feet) (over 35 feet)
Hydraulic 15 20 30
Airblast 4 10 5 15 7 30
Mist blower 3 4 5
Airplane 1 2 2


REMARKS






- -6-


TABLE III


AMOUNT OF PESTICIDE REQUIRED PER 100 GALLONS


Chemical
Formulation


Gallons of spray applied per medium sized tree


20 10
(Dilute) (2x)


7.5
(3x)


5 4 2.5 2
(4x) (5X) (8x) (10x)


Pounds
per tree Pounds of wettable powder per 100 gallons of water
Benlate 50% WP .08 0.4 0,8 1.2 1.6 2 3.2 4
Cyprex 65% WP .20 1 2 3 4 5 8 10
DuTer 47.5% WP .08 0.4 0.8 1.2 1.6 2 3.2 4
Guthion 50% WP .20 1 2 3 4 5 8 10
Parathion 15% WP .40 2 4 6 8 10 16 20
Sevin 80% WP .30 1.5 3 4.5 6 7.5 12 15


Ounces Ounces of emulsifiable concentrate per 100 gallons
per tree of water
Dimethoate
2.67 Ibs./gal. EC
(DeFend or Cygon) 1.3 6.7 13.4 20 26.8 33.5 53.6 67

Guthion
2 lbs./gal. EC 6.4 32 64 96 128 160 256 320
Malathion
5 Ibs./gal. EC 4 20 40 60 80 100 160 200
Parathion
2 Ibs./gal. EC 4 20 40 60 80 100 160 200
Systox
2 Ibs./gal. EC 3.2 16 32 48 64 80 128 160
Torak P
4 Ibs./gal. EC 3.2 16 32 48 64 80 128 160
Zolone
3 Ibs./gal. EC 4 20 40 60 80 100 160 200


pint = 16 oz. = 473 milliliters
qt. = 32 oz. = 2 pints
gal. = 128 oz. = 4 qts. = 8 pts.
oz. = approx. 30 milliliters


lb. =
lb. =
lb. =
lb. =


16 oz.
1.6 oz.
6.4 oz.
12.8 oz.


1These figures are for medium size (25 35 ft.) trees. For larger trees, multiply
either the amount of pesticide formulation per 100 gallons or gallons per tree by
1.25. For smaller trees, multiply either gallons per tree or amount of pesticide
formulation by .75,








/




,.4 I I


-7-


TABLE IV

RESIDUE TOLERANCES AND LIMITATIONS FOR CHEMICALS RECOMMENDED FOR
PECANS IN THIS PUBLICATION


RESIDUE TOLERANCE
(oom)


INTERVAL BETWEEN LAST APPLICATION
AND HARVEST AND OTHER RESTRICTIONS


Benlate 0.2 1 lb. of 50% formulation/acre.
Do not apply after shucks split.

Cyprex 0.3 Limit: 0.33 0.65 Ibs. ai/100 gal.
up to 700 gal/A by ground equipment.
Do not apply after shucks start to
open. Do not graze meat or dairy-
animals in treated orchards.

Dimethoate 0.1 Do not apply within 21 days of har-
vest. Do not graze livestock in
treated orchard.


Systox 0.75 Do not apply within 21 days of
harvest. Do not graze livestock in
treated orchards.



rer 0.05 Limit: 6.5 lbs. of 47.5% formulation/
acre. Do not apply after shucks
start to open. Do not graze livestock
in treated orchards.


0.3


Do not apply after shucks split.
Do not graze livestock in treated
orchards within 21 days after treatment.


Malathion 8.0 No time limitations.

Parathion 0.1 Do not apply within 15 days of harvest
or after shucks begin to open. Do not
graze meat or dairy animals in treated
orchards.

Sevin 1.0 No time limitations. Do not apply
more than 7.2 Ibs. actual per acre
per application.
Torak 0.01 Do not apply after shucks split. Do
not graze livestock in treated areas.
Do not feed treated cover crops to
livestock or poultry.


0.05


Do not apply more than 20 Ibs. (53 1/3
pints per acre per year). Do not
apply after shucks split. Do not
allow livestock to graze treated
cover crop or feed cover crops to
livestock.


CHEMICAL


Guthion


ol one







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