| Summary: | Whitefly populations were assessed under different IGR exposure levels, and compared to Admire. When used alone during the season Applaud, Knack, and Sterling significantly reduced immature colonization similar to the standard Admire application and significantly greater than the untreated melons. Applaud treatments, regardless of spray frequency, showed the most consistent reduction in immature whiteflies. Applaud through its vapor activity also appeared to provide a long residual period of control against nymphs. Single applications of Knack and Sterling were considerably less effective in preventing colonization than applying these material twice during the season. These compounds appeared to have considerably less residual activity, which is consistent with their modes of activity. All of the IGRs had a significant impact on the distribution of nymphs among the leaves on the primary vine. In addition, Applaud provided the best melon quality. We now have a good understanding of how the IGRs influence whitefly population growth, the residual mortality of the IGRs and proper application timing for whitefly management. This information will allow us to develop a simple and reliable method that growers and PCAs can use to assess product performance and time spray applications.
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