Texas Cooperative Extension

Texas Cooperative Extension
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July 30 , 2004

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.

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.

Blackmargined aphids - Populations of blackmargined aphids have peaked and crashed in many Black pecan aphid damage
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.

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.

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.

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.

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

For more information, contact:
Bill Ree
Extension Program Specialist
Texas A&M University-Riverside Campus
Bryan, TX 77806-2150
Phone: 979-845-6800
Email: w-ree@tamu.edu

The information given herein is for educational
purposes only.  References to commercial products
or trade names are made with the
understanding that no endorsement by
Texas Cooperative Extension is implied.

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