Title: Pecan insect and disease recommendations
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 Material Information
Title: Pecan insect and disease recommendations
Physical Description: Book
Creator: French, W. J.
Publisher: Agricultural Research Center, IFAS, University of Florida
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Bibliographic ID: UF00076548
Volume ID: VID00001
Source Institution: University of Florida
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Resource Identifier: oclc - 153982088

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AGRICULTURAL RESEARCII CEMTEP !HOUTICELLO
Monticello, Florida

Mfonticello ARC Mimeo Report BB-1972-1 HUM&UBnRAR9 2
REVISED F
SFEB 72
PECAN INSECT AMD DISEASE RECOMMEN1 ATION

U. J. French and S. S. Fluke I'.F.A.S. Univ. of Florida


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 of high yields year after year. Trees
which are prematurely defoliated by insects, mites, and diseases frequently
set a light crop the following year. Although todays' pecan grower is fortun-
ate to have effective fungicides, insecticides, and improved spray equipment
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. Perhaps
the three most important factors in a spray program are timing, coverage, and
rate.

Timing Pecan diseases, such as scab, must be prevented by providing
a protective 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 some-
what 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 snrays accordingly. 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-lad-
ened air, thus poor coverage results. Small to medium sized trees can be row
sprayed while very large trees should be circled.


1Assistant Plant Pathologist and Assistant Entomologist


500 cc 1/19/72









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: Du-Ter 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 Du-Ter required per 100 gallons or 4 pounds
per 500 gallon tank.

The following spray schedule (Table 1) will give commercial control of
important disease and insect pests. The schedule is designed for scab suscep-
tible 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 nutri-
ent sprays should be applied separately; do not mix with fungicides or insect-
icides.

PRECAUTIONS

Parathion, EPI, and Guthion 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 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.







-3-

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


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

Approx. April 15


Scab


Du-Ter or Cyprex


Leaf
case-
bearer


Scab


Downy
Spot


Du-Ter or Cyprex


Nursery
blight


Do not use Cyprex on
Moore or Van Deman Var.
Do not graze livestock
in treated groves except
where Malathion or Bor-
deaux are used alone.
(If a spray program was
not followed last year
add an insecticide to
control over-wintering
leaf and nut casebearer.)


Increase gallonage per
tree as the foliage
grows. Wettable powders
such as Du-Ter are some-
times physically incom-
patible with emulsifi-
able concentrates. Check
compatibility of Du-Ter
with EC insecticides
before mixing large
amounts.


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

Approx. May.1


Scab


Du-Ter or Cyprex


Powdery Add sulphur to Du-
mildew Ter or Cyprex or
use Bordeaux alone.


Nut
case-
bearer


1.
2.
3.
4.
5.


Thiodan or
Parathion or
EPN or
Guthion or
Malathion.


Proper timing for nut
casebearer is very im-
portant. Dimethoate
is effective principal-
ly against aphids. Bor-
deaux is not compatible
with any of the other
materials listed.


Mites Any of the above.

Aphids Dimethoate or any
of the above.


4. 2nd cover spray:
Three weeks
after No. 3


Approx. May 21


Scab


Powdery
mildew

Aphids


See 1st
cover spray


If weather is rainy,
apply fungicide at two-
week intervals or in-
crease rates by 1/2.


Mites
LFor 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
nnrt-h lnr-ida)l


PEST TO SPRAY MATERIAL
CONTROL For rates see
TahlP TT


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


Scab
Downy spot
Brown leaf
spot
Powdery
mildew
Mites


See first
cover spray

Parathion or
Malathion


Shuckworm EPN, Guth:
Pecan
weevil EPN
Black
aphid Dimethoate


ion,


Do not apply after shucks
start to open. If rainy
weather conditions exist,
it may be necessary to
apply 7th cover spray.



or Parathion


REMARKS


----


--


5. 3rd cover spray Scab Begin checking small nuts
Three weeks Downy spot for shuckworm damage. See
after No. 4 Brown leaf 4th cover spray for recom-
spot mendation.
Approx. mid-June Powdery See first
mildew cover spray
Mites
Aphids

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

Shuckworm Guthion, EPN, or Parathion

7. 5th cover spray: Scab Apply EPN for pecan weevils
Last week in July Downy spot when three or four adult
or first week in Brown leaf weevils can be jarred from
August. spot tree. Repeat application
Powdery See first in three weeks.
mildew cover spray
Aphids
Mites

Shuckworm Guthion, EPN, or Parathion
Pecan EPN
weevils






-5-
TABLE II
AMOUNT OF PESTICIDE REQUIRED PER 100 GALLONS

Gallons of spray applied per medium sized tree


Chemical


20 10


6.66 5


4


2.5 2


Formulation (Dilute) (2x) (3x) (4x) (5x) (8x) (10x)
Pounds
per tree| Pounds of wettable powder per 100 gallons of water

Du-Ter 0.08 0.4 0.8 1.1 1.6 2.0 3.2 4.0
47.5% WP -
Cyprex 0.20; 1 2 2.7 4 5 8 10
65% WP
Sulfur or
Malathion 0.60 3 6 9 12 15 24 30
25% WP
Parathion 0.40 2 4 6 8 10 16 20
15% WP
Guthion'
50% WP or 0.40 j 1 2 3 4 5 8 10
EPN 50% WP
Thiodan 50% WP 0.40 2 4 6 8 10 16 20
Bordeaux Mixture
(copper sulphate .8-.2 4-1 8-2 *
and lime)

Ounces Ounces of emulsifiable concentrate
per tree! ... per.100 gallons of water

Parathion
2 lb/gal EC 4 20 40 60 80 100 160 200
or Malathion
5 lb/gal EC
EPN 5 lb/gal EC 2.5 12.5 25 37.5 50 62.5 100 125
Dimethoate
2.67 lb/gal EC 3.2 16 32 48 64 80 128 160
(DeFend or Cygon
Thiodan 9.6 48 96 144 192 240 384 480
2 Ib/gal EC
EPN 2 Ib/gal EC 6.4 32 64 96 128 160 256 320
or Guthion
9 Ih/oal r.


16 oz. =
32 oz. =
128 oz.=


473 milliliters
2 qts.
4 qts. = 8 pts.


= approx. 30 milliliters
= 16 oz.


.1 lb.
.4 lb.
.8 lb.


= 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.


*Low volume application of Boodeaux mixture is not recommended.


1 pint
1 qt.
1 gal.
1 oz.
1 lb.


'"


- --16--~







-6-
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


EPN 0.5 Do not apply within 21 days of harvest.


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


Malathion 8.0 No time limitations.


Parathion Extended Do not apply within 15 days of harvest
or after shucks open.


Bordeaux Mixture Exempt No time limitations.


Du-Ter 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.


Cyprex 0.3 Limit: 7.0 lbs. of 6570% formulation/acre.
Do not apply after shucks start to open.
Do not graze meat or dairy animals in
treated orchards.


Sulfur Safe No time limitations


Thiodan 0.2 Do not apply after shucks begin to ppen.
Do not graze meat or dairy animals in
treated orchards.


Dimethoate 0.1 Do not apply within 21 days of harvest.
Apply only with ground equipment. Do
not graze livestock in treated orchards.


CHEMICAL







-7-

TABLE IV

GALLONS OF SPRAY BY TREE SIZE


TYPE OF EQUIPMENT


GALLONS OF SPRAY BY TREE SIZE


Small
(Under 25 feet)


Medium
(25-35 feet)


Large
(over 35 feet)


Hydraulic


Air blast


Mist blower


Airplane


15


4 10


3


1 1/2


20


5 15


4


2


30


7 1/2 30


5


2 1/2


I




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