Thrips Risk Assessment and Use of Supplemental Foliar Insecticide Applications

Thrips are consistent and predictable insect pests of seedling cotton in Georgia and the southeastern US.  Excessive thrips feeding results in crinkled malformed true leaves, stunted plants, delayed maturity, reduced yield potential, and in severe cases stand loss. The neonicotinoid insecticides imidacloprid or thiamethoxam applied as a commercial seed treatment (NSTs) are used as a preventive treatment by most growers for early season thrips control.  NSTs are active on thrips for about 21 days after planting (DAP); however, supplemental foliar sprays are needed in some environments.  Two cultural practices have a significant impact on thrips populations: 1) planting date and 2) tillage practice.  Thrips infestations are typically higher on cotton planted during April and early May compared with late May and June plantings.  Thrips infestations are also significantly greater in conventional tillage systems compared with reduced tillage systems.  Based on these two cultural practices, a risk index of thrips infestations may be predicted for any cotton field. The use of supplemental insecticide applications for thrips will be contrasted in these two risk environments.