I’ve received several phone calls over the past few days about thrips in seedling cotton. Thrips pressure is variable by location with some areas reporting treatable numbers and others finding a few adults scattered around.  Application timing is critical for the best control.  Our research has shown that applications made early, before the second true leaf, provides the most benefit.

Options for foliar oversprays are limited to organophosphates  (Acephate, Bidrin, Dimethoate) and Intrepid Edge. OP resistance is present in West TN and while Acephate may provide some relief a more consistent option is 3.0 oz of Intrepid Edge. Also, increasing the rates of OPs may help some but overcoming resistance with higher rates often doesn’t provide consistent control and can be an expensive mistake.

The take home message, use acephate or other OPs with caution especially if you received questionable control last year and higher rates often aren’t the answer. Intrepid Edge, although the most expensive, is most consistent option that won’t flare spider mites or aphids. Surfactants aren’t required for Intrepid Edge but are highly recommended. Application with a herbicide such as Roundup or Liberty will work.

Side note: I’ve got word that Bidrin is in short supply so if you don’t have what you need for thrips I would think about making other arrangements.

The thrips infestation predictor tool uses planting date, precipitation, and temperature to create an estimate of the size of local thrips population and the susceptibility of seedling cotton to infestations of tobacco thrips (the predominate thrips species in Tennessee). Models can be run for two weeks  beyond the current date. Planting decisions should be made based on weather, opportunity and agronomic considerations not based on this model.  The model is useful for predicting/anticipating the need for a thrips overspray in addition to an insecticide seed treatment.

Utilizing the model is simple,  users select a planting date and a location based on an interactive map. The model will predict thrips risk for planting dates in a designated time frame. As an example, cotton planted before May 5th in West Tennessee has a somewhat lower risk than cotton planted on May 15th.  If you look at the within season model, cotton planted May 21- 31 has a much higher risk of thrips infestations than cotton planted in early May.  Beware,  the accuracy of this model often improves as we approach the intended planting date and rerunning the model as you get closer to planting is a good practice.  This tool has helped us time our planting of thrips trials to maximize thrips numbers and will hopefully help you do the opposite.