Thrips, Wheat and Intercropped Cotton

Prior to the year 2000, extensive research concerning cotton and wheat relay intercropping, had been conducted in South Carolina, Georgia, and Mississippi, but currently has not been investigated in the northern regions of the cotton belt. Since then, there have been significant advances in cotton production technology; more specifically, the introduction of glyphosate tolerance and Bacillus Thuringiensis (Bt) toxin expressions in cotton. These relatively new technologies have significantly impacted cotton production practices, prompting a renewed interest in intercropping. In addition, varieties expressing the recently released Roundup Ready Flex technology appear to mature slightly earlier, potentially allowing cotton to be intercropped with wheat in the northern regions of the cotton belt. The purpose of this experiment was to demonstrate the feasibility of relay intercropping wheat and cotton in North Carolina, where double cropping wheat and cotton is not consistently successful. Thrips management has been identified as a unique component of intercropping, versus mono-culture production, where there is a potential cost savings due to the suppression of thrips populations in the presence of wheat. The focus of this experiment was to compare and characterize the effects of intercropping and traditional management strategies on thrips populations in cotton. Five thrips management strategies were applied to intercropped and mono-cropped cotton in two locations in 2009. The intercropping system was also compared to double- cropped wheat and soybeans for economic analysis. Preliminary results indicated that relay intercropping cotton significantly reduces thrips populations versus mono-cropped cotton. In intercropped cotton, seed treatments alone provided adequate thrips control to prevent significant cotton yield loss resulting from thrips injury. Intercropping reduced wheat yields by 15% to 40% and had insignificant effect on cotton yields. Economic analysis indicated that relay intercropping cotton in wheat is economically viable and that it provides similar returns to that of double-cropped wheat and soybeans.