Effect of methomyl and oxamyl soil applications on early control of nematodes and insects

BACKGROUND: Methomyl is a widely used carbamate insecticide that has traditionally been applied as a foliar spray. More recently, methomyl has been labeled as a soil application via drip chemigation. Not much is known about the insecticidal and nematicidal potential of soil-applied methomyl. Methomyl soil applications were evaluated for their potential to control soil nematodes and foliar insect pests in a series of lab and greenhouse tests. RESULTS: Methomyl showed rapid knockdown of Meloidogyne incognita (Kof. & White) Chitwood in aqueous assays, with EC50 and EC90 values that were similar to oxamyl and averaged 4.9 and 15.2 mg L−1. In the greenhouse, soil applications of methomyl ranging from 0.56 to 4.0 kg ha−1 provided significant M. incognita control similar to oxamyl during early growth (up to 25 days after planting) of pea and bean. Higher application rates and split applications improved nematode control, but also increased the risk of phytotoxicity. Methomyl soil applications were highly effective on several insects including Myzus persicae (Sulzer), Aphis gossypii (Glover), Frankliniella occidentalis Perg. and Spodoptera exigua (Hubner). Methomyl was about 5–9-fold more potent on M. persicae and A. gossypii when applied via soil drench as opposed to foliar spray. Potency on Bemisia tabaci Genn., S. exigua and Trichoplusia ni Hubner was about the same with the two application methods. CONCLUSION: Methomyl soil applications showed good potential for early control of various insect and nematode pests. Further testing is required to verify activity under field conditions. Copyright © 2011 Society of Chemical Industry