Control of corn flea beetle and Stewart's wilt in sweet corn with imidacloprid and thiamethoxam seed treatments

Abstract

Two field-plot experiments were conducted in western and central New York to evaluate imidacloprid and thiamethoxam seed treatments for control of corn flea beetle, Chaetocnema pulicaria Melsheimer, and Stewart's bacterial wilt in three varieties of sweet corn. Seed treatments significantly reduced flea beetle feeding injury to leaves in all varieties and reduced disease incidence 37–83% in the susceptible variety ‘Sprint’. Seed treatments did not control Stewart's wilt as effectively as genetic resistance. Disease incidence in the resistant varieties ‘Dynamo’ and ‘Bonus’ was relatively low (⩽5%) with or without a seed treatment. Additional on-farm evaluations conducted in western New York confirmed the results obtained from our field plots with incidence of Stewart's wilt ≈88% lower in imidacloprid-treated fields compared with non-treated fields. Laboratory germination tests indicated that seed treatments with imidacloprid may have some phytotoxic effects, depending on sweet corn variety and vigor of the seed lot. A general recommendation is that only high quality seed lots should be treated with imidacloprid and that carry-over seed should not be used.