Pesticide and Seasonal Effects on Within-Plant Distribution of Tetranychus cinnabarinus (Boisduval) (Acarina: Tetranychidae) in Cotton

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Abstract
The effects of five pesticides on the within-plant distribution of Tetranychus cinnabarinus (Boisduval) were examined in a 2-year field study in cotton at Imperial Valley, Calif. The numbers of adult female mites were recorded from the upper 16 mainstem node leaves on 96 cotton plants weekly during the 1982 and 1983 growing seasons. Within-plant distribution of the mites on the mainstem node leaves was not significantly affected by the pesticides. Throughout the season, mainstem node leaf 5 consistently had one of the highest densities of mites; in almost all cases, no other mainstem node leaf had significantly ( P < 0.05) more mites than leaf 5. Thus, mainstem node leaf 5 is the recommended sampling unit.