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This newsletter is being supported
by the
TEXAS PECAN GROWERS ASSOCIATION
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July 30
, 2004
#04-6 |
Anyone wanting this newsletter by e-mail please send me a note
at w-ree@tamu.edu and I’ll
put you on the list. If any one has had an address change from
a rural route box number to a 911 address please let me know
so I can make the change. I have had to drop several producers
because of returned letters with incorrect/old addresses. DISEASES
Powdery mildew: Pecans with powdery mildew will be covered
with a white powdery substance. This fungus only attacks
the outer layer of plant cells on the pecan shuck and is
not a threat to the crop. This fungus is quite common, occurring
during the mid summer months and no yield losses have ever
been attributed to this fungus.
INSECTS
Aphids:
Blackmargined aphids - Populations of blackmargined
aphids have peaked and crashed in many 
orchards. In fact
earlier this month we were having a hard time finding aphid
populations in sufficient numbers for some studies.
Yellow
pecan aphid - this is the other “honeydew “ aphid
and so far I have not received any reports of this species.
Black pecan aphid (See photo right) - Black pecan
aphids generally build during the late season. Watch for
leaflets with distinct angular yellow blotches. Adults and
immatures of this aphid species can be found on both the
upper and lower surfaces of the leaflets. Populations will
build in the interior portion of the canopy which is shaded.
The economic threshold for this pest is only an average of
3 per compound leaf. Insecticides for BPA include: chlorpyrifos
(Lorsban 4E) @ 2 - 4 pt per acre; dimethoate (Dimethoate)
@ 1 pt per acre, imidacloprid (Provado 1.6F) @ 7 - 14 ounces
per acre; malathion (Malathion 57% EC) @ 1-2 pints per acre
and pymetrozine (Fulfill) @ 4 oz per acre.
Pecan weevil: For those producers with pecan weevils it
is time to prepare for this pest. Adult emergence traps -
wire cone traps, “Tedders” or pyramid traps and/or
Circle traps, should be in place by the first week of August.
The objective of the pecan weevil management program is pretty
simple - that is, prevent female weevils from ovipositing
in nuts. In order to do this we recommend you do three things:
1) monitor kernel development to know when pecans are susceptible
to oviposition; 2) use some type of adult emergence trap
(wire cone, pyramid, Circle) to monitor adult activity and
3) use carbaryl insecticide.
Adult female pecan weevils are not able to successfully
oviposit in pecans until the kernel is in the late gel stage/early
dough stage. Pecans mature from the tip end towards the stem
end so always check the tip end for the most mature kernel
development.
The first insecticide application should go out around August
20 or when kernel development of the earliest maturing varieties
you want to protect reach the late gel stage. This initial
treatment will go out regardless if you have collected adults
in your traps. A second application should go out 10 days
later if you are collecting adults in traps. Continue to
monitor traps up to harvest. A pecan weevil management program
will take at least 2 treatments but sometimes additional
applications will be needed.
Our recommended insecticides for pecan weevil include carbaryl
(Sevin 80S, Sevin 50WP) and cypermethrin (Fury 1.5ES). Do
not add any binding or sticking agent with your spray. For
pecan weevil control you do not want your insecticide bound
to the foliage. Note: Fury is being fazed out and replaced
with a similar product called Mustang Max. These two products
are almost identical, however, the active ingredient in Fury
is 1.5 lbs AI per gallon and Mustang Max is only 0.8 lbs
AI per gallon and the labeled rates per acre for both products
are almost identical.
Normal Adult PW Emergence Curve
Hickory shuckworm: Unfortunately we are not able to monitor
HSW activity like we are with pecan nut casebearer and pecan
weevil. Applications of insecticides for HSW are applied
at a crop stage of half-shell hardening. The time of this
stage will vary across the state and by variety but generally
occurs during the first two weeks of August. You can check
this stage by taking a pocket knife and starting at the tip
of the nut, make cross sectional cuts where you should be
able to feel the shell hardening process as it occurs.
In commercial orchards we recommend two insecticide applications
beginning at half shell and a second application 10 to 14
days later. Recommended insecticides include: tebufenizide
(Confirm 2F) @ 8 - 16 oz per acre; chlorpyrifos (Lorsban
4#) @ 2-4 pts per 100 gallons; esfenvalerate (Asans XL) @
2.56-4.27 oz per acre; phosmet (Imidan 70WSB) @ 1.5-2.0 lbs
per 100 gallons; Spinosad (SpinTor 2SC) @ 4 - 10 oz per acre
and methoxyfenozide (Intrepid 2F) @ 4 - 8 oz per acre.
Stink bugs/Leaffooted bugs: During the late summer adult
stink bugs and leaffooted bugs begin to leave other hosts
as they mature and seek out new feeding sites. Damage from
stink bug and leaffooted bugs can be characterized as black
spots on kernels at harvest. Be aware of surrounding crops
such as soybeans, grain sorghum, corn, etc. that are maturing
which can result in adults moving into your orchard. One
method of SB management is the use of trap crops planted
around the orchard. The trap crop idea is to plant a very
desirable host to draw the adult stink bugs away from pecans
and into these alternate host plants. Anyone wanting more
information on the use of trap crops should give me a call.
MITES
Pecan leaf scorch mite: The only reports I have received
so far on scorch mite activity have been from Bastrop and
Wilson counties. Feeding by scorch mites result in a bronzing
of the leaflets along the mid vein of the leaflet and leaf
drop. Scorch mites tend to like hotter, drier dusty conditions
and infestations generally start in the lower portion of
the canopy. Controlling mites can be costly so it is best
to catch infestations early. Recommended treatments for mites
include: dicofol (Kelthane MF) @ 1.5 -2.0 quarts per acre;
fenbutatin-oxide (Vendex 50WP) @ 4-8 oz per 100 gallons;
hexythiazox (Savey 50WP) @ 3-6 oz per acre; and Acramite
@ 1 lb per acre. Dimethoate at 1 pt per acre can act as a
suppressant.
CROW MANAGEMENT
For those producers that are using DRC 1339 you need to start
prebaiting your platforms. Although there has been a request
for some label changes at this time the start date for
using the hot bait is still September 1.
HERBICIDES
Postemerge herbicides - work either by foliar contact of
are absorbed by the plant and kill systemically.
Contact - Gramoxone Extra (Paraquat) - annual weeds and
grasses and top kill and suppression of perennials. HIGHLY
TOXIC TO HUMANS.
Systemic - Roundup (glysophate) - Most annual weeds and
grasses and many perennials; Touchdown (Sulfosate) - most
annual weeds and grasses and many perennials; Fusilade 2000
(fluazifop-butyl) - most grasses, no broadleaf weeds; Post
(sethoxydim) - most grasses, no broadleaf weeds.
Pre-emerge herbicides - do not generally harm existing weeds.
Their main effect is to prevent seed germination.
Surflan (Oryzalin) - Broad spectrum of annual weeds or grasses
Solicam DF (norflurazon) - broad spectrum of annual grasses
and weeds.
Treflan EC (trifluralin) - broad spectum of annual grasses
and weeds. Must be incorporated into the soil.
MEETINGS:
Texas County Field Days:
August 17, 2004 - tentative
Comanche County
Contact: Bob Whitney 325-356-2539
National/State Meetings
August 12-14, 2004
NOGATEC ITESM Campus, Laguna, Torreon, Coah., Mexico
Contact: Phone - 52-871-7296341
Email: myriam.villarreal@itesm.mx
September 15-16, 2004
Alabama Pecan Growers
Fairhope, Al
Contact: Monte Nesbitt, gcspecan@bellsouth.net
September 17, 2004
Arizona Pecan Growers
Palo Verde Holiday Inn, Tucson, AZ
Contact: Mike Kilby, Phone: 520-403-4613 or email mkilby@ag.arizona.edu
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