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Extension Agent: Pecan casebearer update

April 26, 2011 at midnight
Updated April 25, 2011 at 11:26 p.m.

Joe Janak

By Joe Janak

Each year is a little different. The pecan nut casebearer is keeping itself a little mysterious. The PNC is a tiny worm that can nearly wipe out a pecan crop if in high population and not controlled, is nearly at the stage for growers to make a decision to spray or not to spray. Typically, the worm infests pecan trees between May 5-12 each year for the first generation, with a second generation about 42 days later.

Pheromone traps set out in Victoria and area counties show the PNC moth is at various stages. In DeWitt County, moths were caught as early as April 15, but in Victoria County, they were first caught April 22. With the help of several growers from throughout Victoria County, we have come up with a preliminary date for looking for PNC eggs and potentially spraying.

Pecan pheromone traps are monitored and located at the following areas in Victoria County: Kernell Moritz, Mission Valley; Ronnie Otto, Burroughsville Road, Victoria; DeAnn Moreno, Wischkaemper Road, Victoria; Charles Nelson, Inez; and Travis and Sara Janak, Parsons Road.

Based on moth catches at the reported sites, the earliest potential spray date is May 3 and a 25 percent egg lay (typical treatment date) on May 5. As we approach those dates, more accurate calculations can be made on the best spray date. Knowing the best spray date or dates is important, but knowing the infestation level or number of larvae is essential, or you are just spraying without full knowledge and not following Integrated Pest Management guidelines. Egg counts and infestation levels need to be made during April 29-May 1 to accurately predict infestation levels and the best spray date.

Texas AgriLife Extension's philosophy on spraying to control any pest, including the pecan nut casebearer, is to use the Integrated Pest Management (IPM) method, whereby growers monitor pest levels, crop production potential, beneficials, economics and finally, if necessary, use the least harmful pesticide. Pecan tree owners can best control the pest by spraying an insecticide into the tree foliage, coating the tiny nutlets to provide protection.

But as of this time, the most likely recommendation if egg count levels are high enough and only one spray date was used would be May 3-5. If two or three sprays were applied to the nutlets instead of just one, dates could be adjusted to May 3 and May 7. The only consideration for multiple spray dates would be if the egg lay is extended or the applicator is using a product, such as Bt, which is a good product, but is short lived.

If spraying is needed, the best advice for homeowners is: Spinosad (SpinTor, Entrust or Greenlight Lawn and Garden), Bacillus thuringiensis or Bt (many products are sold with Bt), or malathion or Carbaryl (Sevin). Other labeled insecticides for pecan nut casebearer include the following: Chlorantraniliprole (Altacor), Chlorpyrifos (Lorsban 4E); Cypermethrin (Ammo); Cyfluthrin (Baythroid); Esfenvalerate (Asana); Diflubenuron (Dimilin); Methoxyfenozide (Intrepid); Phosmet (Imidan); Tebufenozide (Confirm); Zeta-cypermethrin (Fury, Mustang Max); Gamma-cyhalothrin (Proaxis); and Lambdacyhalothrin (Warrior with Zeon). Please read and follow all label directions of products used. Biological control options include: Spinosad (SpinTor or Entrust); Tebufenozide (Confirm); and Bacillus thuringiensis (Bt).

For greater effectiveness with an insecticide, remember to buffer the water with a commercial buffering product or vinegar if you have alkaline water.

Zinc, a nutrient, also should be mixed with the insecticide and sprayed on the leaves. In fact, for proper management, at least two to three applications of zinc should have already been applied within the past 45 days.

If your pecan tree varieties are susceptible to scab, a common pecan fungus, fungicides should be applied. Abound and Enable are the fungicides recommended for homeowners but have been hard to find, with others available for commercial producers. With no rain and little free moisture recently, the occurrence of scab disease will hopefully be minimal and a fungicide not warranted.

Nitrogen fertilizer should be applied for the second time now at the rate of 50 pounds per acre or about to pound of 21-0-0 fertilizer per inch trunk diameter on mature trees.

LUNCH AND LEARN WITH THE MASTERS

"Citrus Greening," by James Denman, Kay Dillingham and Pat Plowman, Victoria County Master Gardeners, Pattie Dodson Health Center, 2805 N. Navarro St. The session is free to the public, from noon to 1 p.m., May 9.

Joe Janak is a Victoria County extension agent.

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