ABSTRACT

Methomyl is released into the environment primarily from its application to plants as an insecticide. The amount of methomyl used annually in the US prior to 1983 was estimated in 1985 to be greater than 4.25 million pounds. Methomyl may be susceptible to significant leaching. Methomyl is used as a foliar spray for the control of many insects on field crops, certain fruit crops, ornamentals and vegetables. Microbial degradation appears to be the major transformation process for methomyl in soil with carbon dioxide as the principal end product; a lag period of one to two weeks may occur in unacclimated soils before biodegradation begins. Methomyl seemed to be stable for about 16 days after application to an alluvial soil, but then degraded faster in the nonautoclaved alluvial soil as compared to autoclaved soil suggesting the importance of microbial degradation. Major general population exposure to methomyl will occur through consumption of contaminated food.