Experiments were conducted across the Mid-South to determine the impact of spider mite infestation timings on cotton yields. Twospotted spider mites were infested at the third true leaf stage, at first flower, and at 200 heat unit intervals after first flower. In these experiments, yield losses caused by spider mites were observed for the three leaf stage until first flower plus 800 heat units. Therefore, cotton is safe from spider mite injury when it reaches 1000 heat units past first flower. In the southern U.S., 35-45 days are needed to accumulate 1000 heat units. As a result, spider mite applications in cotton can be terminated about 35 to 45 days after first flower. This information will allow growers and consultants to improve IPM strategies for spider mites in cotton.
