Effects of Rainfall on Persistence of Phosmet Residues on Peach: Implications for Integrated Pest Management Programs1

Abstract

Natural or artificial rainfall of 15 to 18 mm during the first 24 h after applications of low rates of phosmet increased losses of deposits by 20 to 30%. Losses also were accelerated when rains occurred 6 to 7 days after applications. Control of the Oriental fruit moth, Grapholitha molesta (Busck), was reduced, and a need to respray was indicated. However, the necessity to respray was not immediate, because reduced residues were effective for 2 to 6 days, vs. the normal 7 to 10 days. Thus, respraying could be delayed 3 to 4 days. The results suggest that when deposits of phosmet were reduced to the minimum necessary for control of Oriental fruit moth, rains of relatively small quantities significantly affect the control obtained.