Alabama Cotton: Thrips Predictor Model Helps Make Management Decisions

Thrips damaged cotton. Photo: University of Tennessee

Spring and warmer weather sends producers to the fields in droves, planting and making decisions about the upcoming growing season. Researchers at North Carolina State University helped to remove some guesswork from cotton management by developing the thrips predictor model.

Predicting Thrips

Dr. Ron Smith, an Alabama Extension entomologist, said for many years specialists and producers have assumed the earliest planted cotton would have the most injury from thrips.

“This model has shown that the peak is not always earlier,” Smith said. “It takes into account the plant date and weather in the farmer’s location to help calculate potential thrips pressure.”

Traditionally, thrips are considered an early-season pest in Alabama cotton, according to Dr. Steve Brown, an Alabama Extension cotton specialist.

“The thrips predictor model has proven that there are other times to look for thrips pressure, aside from the last week of April and first week of May,” Brown said.

Simply put, thrips pressure predictions were educated guesses until researchers at NC State combined years of trial research data from universities across the Southeast.

Thrips Infestation Predictor for Cotton

NC State’s thrips infestation predictor model combines trial research data, with rainfall amounts, degree-days and long-term temperatures. This information is used to predict when growers may see the highest concentration of thrips in the field.

According to the NC State Climate Office website, the Thrips Infestation Predictor for Cotton uses weather data to make predictions of:

  • thrips dispersal timing
  • cotton growth affecting seedling susceptibility
  • injury risk that results from thrips dispersal and seedling susceptibility occurring at the same time

Smith said entomologists generally determine the movement of thrips from wild weeds and other host plants by the amount of rainfall and the temperature—which also influences how quickly cotton plants grow.

“Weather is a major factor in the movement of thrips from host plants to cotton seedlings,” Smith said. “More rain means the thrips will stay longer on the host plants before moving. Cotton is most susceptible when it is slow-growing and before the fifth true leaf.”

AgFax Weed Solutions

According to the model, mid-May planted cotton will face higher pressure than early-planted cotton. North Alabama cotton may face intense pressure, while the pressures on central and southern Alabama cotton are much lower.

Brown, who is also an assistant professor in the Auburn University Department of Crop, Soil and Environmental Science, said the model is a valuable tool for producers.

“With the loss of some good insecticide protectants—and resistance to some others—the model provides farmers with valuable information,” Brown said. “You can run the model with multiple times and dates to determine a predicted time of impact in a specific location.”

Both Brown and Smith said the ability to choose specific locations and see the difference in pest pressure timing is a tool farmers did not have access to when making management decision prior to the development of the model.


Smith said Extension professionals will keep a close eye on cotton in North Alabama, and continue to consult the model. In mid-May, they will make recommendations for timing of foliar applications.

“The model signifies expected pressure by color,” Brown said. “Producers who find their cotton fields in red areas should anticipate more problems and prepare to intervene with other protectants.”

More Information

Brown said heavy residue tends to help minimize cotton thrips damage. Therefore, producers who planted into heavy residue may see fewer thrips and reduced cotton injury.

Producers can access the Thrips Infestation Predictor for Cotton through the North Carolina Climate Office website.

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