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Some Take Home Points About Insect Control From The Winter Meeting Season
DR. SCOTT STEWART
JACKSON, TENN.
Below is a synopsis of take home points about insect management that I tried to make during the winter meeting season. Obviously, I’ll get into many of the topics in greater detail as the season progresses, but here is some food for thought.
Corn
• Insecticide seed treatments, which come standard on corn, generally provide pretty good insect control. The higher seed treatment rates or supplementing with in-furrow liquid or granular insecticides is advised for specific circumstances such as where cover crops are used or fallow fields are put into production.
• The primary benefit from Bt corn is from the management of corn borers. Bt corn can provide substantial value in areas where non-Bt corn is traditionally planted in the area.
* A non-Bt corn refuge is required, but the requirements differ considerably depending on whether a farm is located in a ‘cotton’ of a ‘corn’ county. Follow guideline appropriate for the corn variety and area. Refuge options are typically included on the seed bag tag.
* I strongly suggest running southwestern corn borer moth traps if growing non-Bt corn. They can be sued to determine if scouting and/or insecticide application is needed.
Soybean
• Kudzu bug and brown marmorated stink bug, both invasive species, are present in many areas across the entire state. Neither has caused substantial problems in the past two years, but keep your eyes open. Brown marmorated stink bugs are becoming more common in the western part of the state. The good news is neither is especially hard to control with insecticides.
• I don’t push insecticide seed treatments in soybean too much EXCEPT in situations were soybean is planted into a cover crop that was burned down late (within three weeks of planting or later). Be especially cautious if the cover included a legume like vetch, winter peas, or clover.
• Scout for slugs just before and/or after planting, especially in areas with high residue or where cover crops were used. You can put out baits to get ‘a feel’ for how many are around.
* We use beer-soaked oatmeal, leave overnight, and check first thing the next morning. You can cover the bait with an aluminum pie pan if you are going to be a little late the next morning. Catching 1 or 2 per bait station is typical and not a big worry in most cases.
* If slugs are present, increase your seeding rate by 5-10 percent, and make sure it dry enough that the seed furrow closes during planting.
• Put footprints in your fields. Scout and spray for insects as needed! Too many folks are spraying when they go across the field ‘just because’.
Cotton
• An imidacloprid base seed treatment or AgLogic 15G are the only primary options for thrips control. You can supplement your seed treatment with thiodicarb (e.g., Aeris), abamectin (Avicta), or acephate (Orthene) for more consistent control.
• Know the tank-mix restrictions on the Engenia or XtendiMax label before making foliar insecticide applications for thrips or other insects. There are more options this year.
• There is not much new with plant bug control. Acephate, Transform, Diamond are backbone of our spray program (more to come later).
• Bollworm resistance to Bt cotton traits (Cry1 and Cry2) is real. The need for insecticide applications for bollworm on WideStrike, TwinLink, and Bollgard 2 varieties is more likely.
* 3-Gene technologies (WideStrike 3, TwinLink Plus, Bollgard 3) are a solution, but scouting is still required.
* Diamide insecticides (Besiege, Prevathon) are the go-to products for bollworm control.
* Treatment of WideStrike, TwinLink, and Bollgard 2 varieties for bollworm is recommended during the blooming window when eggs are present on 20-30 percent of plants, or when 4 or more larvae or 6 percent fruit damage (squares and flowers) is observed. Treat on the front end, avoid chasing larger worms.
General
• Be a good neighbor when making pesticide applications, and make the effort to communicate with beekeepers near your fields. It’s best when the first interaction is not a complaint or confrontation!
• The 2019 Insect control recommendations are available for cotton, corn, soybean, sorghum, wheat, and pasture.
• New mobile-friendly pest control resources are available at https://guide.utcrops.com/. ∆
DR. SCOTT STEWART: IPM Extension Specialist, University of Tennessee
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