Title: Pecan insect and disease recommendations
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Title: Pecan insect and disease recommendations
Physical Description: Book
Creator: Ball, J. C.
Publisher: Agricultural Research Center, Agricultural Experiment Station, IFAS, University of Florida
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Bibliographic ID: UF00076496
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(-,i*,, Revision of no.

r (. .'P AGRICULTURAL RESEARCH CENTER MONTICELLO /
AGRICULTURAL EXPERIMENT STATION IFAS.
UNIVERSITY OF FLORIDA GAINESVILLE, FL R

Research Report BB-1975-1 March k, 7ANy
REVISED D AfR o 1977

PECAN INSECT AND DISEASE RECOMMENDATIONS
J. C. Ball and W. J. Frenchl,2 lJUn of Ioric~a


Disease and insects are often the limiting factors in the production of
pecans in Florida. The nut requires about 7 months to develop and during that
time is subject to attack by a variety of pests. A good disease and insect
control program is important, not only in protecting the maturing crop, but it
is essential to the production to 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 fungicide sprays than
resistant varieties. Check with your county extension director to determine the
most suitable varieties for local conditions. Although today' 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 re-
quires 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 shucks 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 380-A, 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 pro-
tective 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
1Asst. Entomologist and Assoc. Plant Pathologist
2Prepared in collaboration with R. S. Mullin, Extension Plant Pathologist,
J. Brogdon, Extension Entomologist





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and time his 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 emergence 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 pyronone (lay a ground cloth under the trees So that the dislodged
weevils can be seen). Spray when adult weevils are found and continue at 10 to 14
day intervals 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 IV). 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-ladened 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 chemical
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 pounds of 47.5% formulation per tree. If 10 trees are
sprayed per 100 gallons of water then 10 times 0.08 equals 0.8 pounds of DuTer required
per 100 gallons or 4 pounds per 500 gallon tank.

The following spray schedule (Table I) will give commercial control of
important 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, do not mix with fungicides or insecticides.









PRECAUTIONS

Parathion, EPN, Guthion, and Disyston 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 pesticides
to adjacent areas. See Table III 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.









TABLE I )

PECAN SPRAY SCHEDULE FOR SCAB SUSCEPTIBLE VARIETIES1


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


PEST TO SPRAY MATERIAL
CONTROL For rates see
Table II.


1. 1st prepollination
spray: When leaves
first show green.

Approx. April 1


Scab


Leaf
and
nut
case-
bearer


Duter, Cyprex or
Benlate


Thiodan or
Parathion or
EPN or
Guthion or
Malathion or
Sevin or
Zolone


Do not use Cyprex on Moore
or Van Deman Var. Do not
graze livestock in treated
groves except where Malath-
ion, and/or Benlate are used.
(If a spray program was not
followed for the last few
years, over-wintering leaf
and nut case-bearers may be
a problem and require treat-
ment.) See diagram for case-
bearer description.


2. 2nd prepollination Scab DuTer, Cyprex or Increase gallonage per tree
spray: When leaves Benlate as the foliage grows. Wet-
are half grown. Downy table powders such as DuTer
spot. are sometimes physically in-
Approx. April 15 compatible with emulsifiable
Nursery concentrates. Check compat-
blight. ibility of DuTer with EC in-
secticides before mixing lar-
ge amounts.


3. 1st cover spray: Scab, Duter, Cyprex or Proper timing for nut case-
When nuts are Powdery Benlate bearer is very important.
1/4" long. mildew Dimethoate is effective prin-
cipally against aphids.

Approx. May 1
Leaf 1. Thiodan or If 1st prepollination in-
and 2. Parathion or secticide was applied for
nut 3. EPN or leaf and nut case-bearer
case- 4. Guthion or control, it is not necessary
bearer 5. Malathion or to repeat this spray.
6. Sevin or
7. Zolone

Aphids, Dimethoate, Disy- Spray for aphids or mites if
Mites ston or any of a- they appear to be on the in-
bove except Sevin. crease.


1For scab-resistant varieties delete fungicide from all but sprays No. 3 and 6.


REMARKS








TABLE I continued

PECAN SPRAY SCHEDULE FOR SCAB SUSCEPTIBLE VARIETIES1


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


PEST TO SPRAY MATERIAL
CONTROL For rates see
Table II.


4. 2nd cover spray: Scab If weather is rainy, apply
Three weeks Powdery See first fungicide at two-week in-
after No. 3. mildew cover spray. tervals or increase rates
Aphids by 1/2.
Approx. May 21 Mites

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


S6. 4th cover spray: Scab Apply second and third
First or second Downy spot shuckworm sprays at two
week in July. Brown leaf spot week intervals.
Powdery See first
mildew cover spray
Aphids
Mites
Shuckworm Guthion, EPN, Zolone or Parathion
Pecan Weevils EPN or Sevin See section on Timing.


7. 5th cover spray: Scab
Last week in July Downy spot
or first week in Brown leaf spot
August. Powdery See first
mildew cover spray
Aphids
Mites
Shuckworm Guthion, EPN, Zolone, or Parathion
Pecan Weevils EPN or Sevin


8. 6th cover spray: Scab Do not apply after shucks
Mid-August to Downy spot start to open. If rainy
1st week in Sept. Brown leaf spot weather conditions exist,
Powdery See first it may be necessary to apply
mildew cover spray. 7th cover spray.
Mites
Shuckworm Guthion, EPN, Zolone, or Parathion
Pecan Weevil EPN or Sevin
Black aphid Dimethoate, Disyston, or Zolone


REMARKS









TABLE II

AMOUNT OF PESTICIDE REQUIRED PER 100 GALLONS1

Gallons of spray applied per medium sized tree


Chemical
Formulation


20
(Dilute)


10
(2x)


6.7 5 4 2.5 2
(3x) (4x) (5x) (8x) (lOx)


Pounds
per tree Pounds of wettable powder per 100 gallons of water
Benlate 50% WP 0.08 0.4 0.8 1.2 1.6 2.0 3.2 4.0
Cyprex
65% WP 0.2, 1 2 3.0 4 5 8 10
DuTer
47.5% WP .08 0.4 0.8 1.2 1.6 2.0 3.2 4.0
EPN 50% WP .40 1 2 3 4 5 8 10
Guthion
50% WP .40 1 2 3 4 5 8 10
Parathion
15% WP .40 2 4 6 8 10 16 20
Sevin
80% sprayable .30 1.5 3 4.5 6 7.5 12 15
Thiodan 50% WP .40 2 4 6 8 10 20
Ounces Ounces of emulfifiable concentrate per 100 gallons
per tree of water
Dimethoate
2.67 lb./gal. EC
(DeFend or Cygon) 3.2 16 32 48 64 80 128 160
Disyston 6 EC 1.6 8 16 24 32 40 64 80
EPN 5 lb./gal. EC 2.5 12.5 25 37.5 50 62.2 100 125
EPN 2 lb./gal. EC 6.4 32 64 96 128 160 256 320
Guthion
2 lb./gal. EC 6.4 32 64 96 128 160 256 320
Malathion
5 Ib./gal. EC 4 20 40 60 80 100 160 200
Parathion
2 lb./gal. EC 4 20 40 60 80 100 160 200
Thiodan
2 lb./gal. EC 9.6 48 96 144 192 240 384 480
Zolone
3 lb./gal. EC 4.3 21.3 42.6 63.9 85.2 106.5 170.4 213.0


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


1 lb.
.1 lb.
.4 lb.
.8 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 eithergallons per tree or amount of pesticides formulation by .75.








TABLE III

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


RESIDUE TOLERANCE
(PPM)


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 lbs. 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. Apply only with ground equip-
ment. Do not graze livestock in
treated orchard.


* Disyston


DuTer


Registered for aphids only. Do not
apply within 30 days of harvest. Do
not apply more than 3 times per sea-
son. Do not graze livestock in
treated orchards.


0.5


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


EPN 0.5 Do not apply within 21 days of har-
vest. Do not graze livestock in
treated orchards.

Guthion 0.3 Do not apply after shucks begin to
open. Do not graze livestock in
treated orchards.

Malathion 8.0 No time limitations.

Parathion 0.1 (interim) Do not apply within 15 days of har-
vest or after shucks open.

Sevin 1.0 No time limitations.
Thiodan 0.2 Do not apply after shucks begin to
open. Do not graze livestock in
treated orchards.

Zolone 0.05 Do not apply more than 20 Ibs.
(53.3 pints per acre per year)
Do not apply after shuck split.


0


CHEMICAL









TABLE IV

GALLONS OF SPRAY BY TREE SIZE


TYPE OF EQUIPMENT


Hydraulic
Air blast

Mist blower

Airplane


GALLONS OF SPRAY BY TREE SIZE
Small Medium Large
(Under 25 feet) (25-35 feet) (over 35 feet)
15 20 30
4 10 5 15 7 30

3 4 5

1 2 2


0


Figure 1. Hibernacula of nut casebearer on primary bud.


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