Broad mites are not a new pest in Michigan, but 2010 was the first year many growers saw plant symptoms. Pests adapted to warmer climates can be present in Michigan but it takes the right conditions to allow them to become a problem. Such was the case with broad mites in 2010. The warmer than usual summer temperatures, especially at night, allowed broad mite populations to increase to the point that they became a visible problem.
Low populations often go undetected since adults are 0.2mm long – smaller than a period (.) and less than half the size of a two-spotted spider mite. In peppers, the first thing noticed in high populations are twisted, curled leaves and deformed fruit (Figure 1). Symptoms appear similar to virus infection or nutrient deficiencies. Broad mites are not easily seen so most growers think they are dealing with a virus problem.
Figure 1. Pepper plants showing twisted leaves and deformed fruit (left) and affected fruit (right).