Saturday, June 10, 2023

Useful tool helps predict need for foliar thrips treatments

• By Scott Stewart •

thrips damage
Thrips damage — photo courtesy University of Tennessee

The Thrips Infestation Predictor for Cotton can be found at This is a useful tool for predicting whether a foliar insecticide application is needed for thrips control in cotton. It uses local weather data in association with a user-defined planting date to estimate the size of the local thrips population, the susceptibility of seedling plants, and thus, the risk of thrips injury. The model is for tobacco thrips, by far the most common species infesting cotton in Tennessee.

You can run the model for planting dates up to two weeks beyond the current date. I do not suggest using this model to make planting decisions, as we all know that is driven by weather and opportunity.

You should choose the most optimal planting dates based on agronomic considerations. However, the model is useful for predicting the need to spray for thrips in addition to using an insecticide seed treatment.

The website is simple to use. You select a planting date and “drop a pin” of your location on the map. The model will predict the risk of thrips injury for that location and planting date plus or minus other possible planting dates in that same time frame.

The graphical outputs are easy to interpret, and explanations of the output are also included (examples below). For example, at this time, it appears that cotton planted in West Tennessee before May 7 is at relatively low risk to thrips injury, and the risk of thrips injury starts to increase beginning about May 10.

HOWEVER, the accuracy of these predictions will improve if you re-run the model closer to or even after the actual planting date.

Give it a try! I think you will like it, and it can help you prioritize the need for making a foliar insecticide application to control thrips.

Dr. Scott Stewart is a University of Tennessee integrated pest management specialist. He may be reached at

relative thrips injury
Red indicates higher risk (note this shows comparison to previous 5 years)
thrips injury risk
Again, red is bad!
thrips damage
Risk for selected planting date vs. other possible dates

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