By Clint Thompson
University of Georgia Cooperative Extension cotton entomologist Phillip Roberts cautions growers about thrips as cotton planting season approaches.
“Thrips are our most consistent and predictable insect pest of cotton, infesting nearly 100% of the cotton acres in Georgia every year. Thrips infestations, historically, have been higher on April or early May-planted cotton. More specifically, thrips infestations tend to be higher on cotton planted before May 10,” Roberts said.
Thrips feed in the terminal bud of the plant and cause the leaves to be ragged and distorted. The results include a stunting of the plants, delays in maturity and even plant death. Roberts also emphasized that this high risk window of thrips infestation a moving target from year to year.
“Temperature and rainfall during winter and early spring have a significant impact on thrips population development and the severity and timing of when these infestations move from alternate hosts to cotton,” Roberts said. “As we near planting I would encourage you to take advantage of the thrips infestation predictor for cotton.”
Thrips Infestation Predictor for Cotton
Roberts also encourages cotton producers to utilize the Thrips Infestation Predictor for Cotton model. It allows farmers to predict the risk of infestations by planting date in different geographic locations.
He insists that regardless of when growers plant, they should apply an at-plant insecticide.
“We consistently observe positive yield response when at-plant insecticides are used for thrips control,” Roberts said.
The effective insecticides include alicarb granules in furrow, liquid applications of Imidacloprid, liquid applications of Acephate in furrow, as well as Imidacloprid seed treatments. Roberts said farmers will see longer residual control of thrips with in-furrow treatments.
Growers need to scout early if they want to successfully manage thrips. Roberts said the threshold is 2 to 3 per plant and immatures present.
“The presence of immatures is an important part of that threshold. As immatures suggest, the at-plant insecticide is no longer providing control. In all of our studies, the optimal timing for supplemental foliar sprays, such as a foliar application of Acephate, the optimal timing for that spray is the one-leaf stage,” Roberts said.