Potential Interactions of Early Season Herbicides and Insecticides in Cotton: Thrips Control and Plant Health

Cotton growth early in the season is affected by damaging levels of thrips in many production fields in Arkansas. During this time, insecticides used to control thrips and herbicides used to control weeds are often present at the same time on the cotton plant. This research explores how various combinations of herbicides and insecticides influence thrips numbers and cotton plant growth parameters early in the growing season. Pathways evaluated included interactions between preemergence herbicides and insecticide seed treatments and interactions between common tank-mixed foliar herbicides and selected foliar insecticides. No interactions in thrips control or plant growth were observed when using preemergence herbicides in combination with insecticide seed treatments. However, efficacy varied between chosen insecticide seed treatments and it may be concluded that in this experiment imidacloprid seed treatments exhibited greater control of thrips numbers than thiamethoxam seed treatments. There were isolated herbicide-insecticide interactions affecting plant growth parameters, but overall the co-application of tested herbicides and insecticides offer cotton producers the ability to integrate thrips and weed control without loss of thrips efficacy or negative impact on plant growth. Herbicide-insecticide interactions examined in this study suggested that pesticide combinations present on the cotton plant simultaneously, early in the season, have no significant interaction which may affect thrips control and early season cotton plant growth