Cotton insecticide trials for the control of silverleaf whitefly Bemesia tabaci Strain B, were conducted on desert grown cotton (Gossypium spp.). The trials contained a newly introduced class of chemistry, Imidacloprid, in the chemical class chloronicotinyl. Imidacloprid, code numbered NTN 33893, was applied to cotton in foliar applications for a three year period beginning in 1991. Efficacy trials were conducted at several locations in Arizona and California. Whitefly pressure remained moderate to high throughout the trial spray periods. The number of whitefly nymphs per leaf area and seed cotton yields were used as a measure of efficacy.

Imidacloprid 240 FS provided good to excellent suppression in all trials when applied at rates of 0.04-0.087 lb. AI/A at weekly intervals. When intervals were expanded to 14 days, rates as high as 0.22 lb. AI/A did not provide good nymphal control. Yields were taken at two separate sites. Treatments containing Imidacloprid produced seed cotton yields 412% and 185% of the untreated control. Both nymphal control and yields compared favorably with the industry standards used in these trials.