Thrips are not only a pain to manage in cotton, but can still rob yield or delay maturity, even when growers use an insecticidal seed treatment and foliar overspray.

Dr. Jack Bacheler, recently retired NCSU Extension entomologist, and NCSU Crop Science graduate student Todd Spivey developed a “one and done” solution to manage thrips at cotton planting. Over the past three years, they looked at the impact high (8x) seed treatment rates, planting dates and Admire Pro in-furrow on thrips levels, plant damage, various plant growth parameters and yield.

Far and away the most efficacious option was Admire Pro @ 9.0 oz/acre plus an insecticidal seed treatment. This held true for each of the three years, but its success was likely dependent on the method of application. In all of the successful tests, they used a stainless steel disc with a #55 orifice (instead of a nozzle) to shoot a stream of finished product into the open furrow ~ 6-plus inches above the furrow.

The Admire Pro + insecticidal seed treatment option has been tried across the Southeast using with flat fan nozzles oriented with the row to apply the Admire Pro in-furrow. In nearly every case, this was no better than using an insecticidal seed treatment alone. Admire Pro without an insecticidal seed treatment was on par with an insecticidal seed treatment alone.

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The flat-fan nozzle applications have not been compared head-to-head with the orifice application. However, the orifice application method cleared cotton from needing a foliar overspray three years in a row. Therefore, I am recommending that growers try using liquid in-furrow imidacloprid (highest labeled rate at 9 gal/A) with an insecticidal seed treatment on a limited acreage in 2014, recognizing that there may be some cases where a clean-up foliar overspray might be needed.

One method of resistance management involves increasing the level of active ingredient to kill resistant insects.  By applying a neonicotinoid in-furrow combined with a neonicotinoid seed treatment, you will be accomplishing this.  However, you will be eliminating another method of resistance management- rotating chemistries- by eliminating your foliar overspray. 

I am not sure what widespread adoption of this method would do to resistance management of thrips in cotton, but my best guess is that it will increase the possibility of creating resistant insects.  Please scout your fields and report any suspected issues of resistance to your county Extension agent.

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