Source:  NCSU COOPERATIVE EXTENSION, 7/27/21


As we near early August, cotton growers should be shifting their focus from early-season insects to late-season pests that arrive after bloom, particularly bollworms and stink bugs. Bollworms have been a persistent pest of cotton over the last few years, a trend that has been driven by increasing resistance to Bt toxins used in cotton and corn.

While the acreage of 3 toxin cotton (Bollgard 3, TwinLink Plus, Widestrike 3) continues to increase across the state, we still have some 2 toxin cotton out there. In 2020, the USDA estimated that North Carolina growers planted approximately 30% of the crop to 2 toxin varieties with about 70% of the crop planted to 3 toxin varieties (USDA AMS 2020). Although we expect that 3 toxin cotton will have minimal injury from bollworms, it will be very important to continue scouting the crop to ensure unexpected injury does not occur. In a previous article, we cover thresholds needed for bollworm management in 2021 depending on the type of Bt expressed in the variety (article link: Additional Threshold for Bollworm Added This Year).

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