Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 9, 1999
Publication Date: November 1, 2000
Citation: MULROONEY, J.E., ELMORE, C.D. RAINFASTING OF BIFENTHRIN TO COTTON LEAVES WITH SELECTED ADJUVANTS. JOURNAL OF ENVIRONMENTAL QUALITY. 2000. 29(6):1863-1866. Interpretive Summary: There are thousands of spray adjuvants currently on the market. Little is known about their effectiveness in increasing the performance of pesticides. This research was designed to evaluate the effectiveness of 11 selected adjuvants to retain and rainfasten an insecticide on the surface of cotton leaves. The results showed that two adjuvants, Bond and Agrimax-3, were found to significantly reduce the wash-off of bifenthrin during simulated rainfall (13 mm). In addition, Bond was not found to antagonize the activity of bifenthrin or a Bacillus thuringiensis formulation. Orchex 796 and Agrimax-3H were found to enhance the retention of bifenthrin on the cotton leaf in the absence of rainfall.
Technical Abstract: Three tests were conducted to determine the ability of 11 selected adjuvants to rainfasten bifenthrin to cotton, Gossypium hirsutum (L), leaves. Included among the selected adjuvants were spreaders, stickers, and a crop oil concentrate. Bifenthrin mixed with each adjuvant was applied to greenhouse grown cotton plants using a spray chamber. Simulated rainfall of 13 mm was then applied to treated cotton plants at 0.25, 1, and 4 hours after treatment. Pre- and post-rain residues were collected from cotton leaves and analyzed using gas chromatography. Bond and Agrimax-3 significantly reduced the wash-off of bifenthrin from cotton leaves. In addition, the retention of each of the bifenthrin/adjuvant mixtures was determined using an immersion cell apparatus. Orchex 796 resulted in twice the retention of the next highest retained adjuvant. Both petroleum and vegetable oils enhance retention of bifenthrin on the leaf surface. Bioassays of the most effective rainfastening adjuvant mixed with bifenthrin and a Bacillus thuringiensis formulation were conducted using tobacco budworm and soybean looper larvae, respectively. The activity of these insecticides was not reduced by the addition of the adjuvant to the spray mixture.