Effects of Planting Date and Variety on Thrips Populations and Injury to Cotton in the Southeastern United States

In some growing seasons in the Southeastern United States thrips (Thysanoptera) are the number one pest of cotton (Gossypium hirstutum) in terms of acres infested. Insecticide resistance among thrips populations in known in the Southeastern United States to neonicotinoid seed treatments, which are the primary method of control of early season crop pests such as thrips in the Southeastern United States. Alternative control methods are needed to provide long-term control of thrips in cotton. Data suggests that thrips species complexes have a distinct peak and trough of population size that occurs early in the planting season of cotton. This suggests that thrips injury to cotton can differ depending on the planting date of the cotton.  To investigate the possibility of planting date's role in thrips injury to cotton, cotton was planted at 10 different times from April 15 to June 15 in 2015, 2016, and 2017 at the Edisto Research and Education Center in Blackville, South Carolina. Thrips population numbers and injury to cotton were tracked throughout the growing season. Another alternative to pesticide applications is the selection of varieties of cotton that are less susceptible to thrips injury. To investigate varietal susceptibility to thrips in Southeastern cotton varieties, ten different varieties of cotton were planted in South Carolina, North Carolina, Virginia, Alabama, and Georgia in 2016 and 2017. Thrips populations and injury to cotton were tracked at all locations.