D3079: Foliar insecticide efficacy on western bean cutworm in field corn and impacts on non-target insects

Insecticide applications are an important part of integrated pest management for western bean cutworm, Striacosta albicosta, whose larval stage feeds on corn and dry beans. Treatment should target the early instars before larvae move into the protection of the plant ear. Ideally, insecticide treatment will be effective at controlling S. albicosta while leaving beneficial insects unharmed. Eight different foliar insecticides along with an untreated control were tested to evaluate their efficacy in western bean cutworm control as well as impacts on beneficial non-target species. Insecticides were applied on July 28, 2021, using a hand-held sprayer designed to mimic aerial application. Each treatment was randomly assigned a plot in four blocks of non-Bt field corn, Zea mays, for a total of four replications per treatment. Ten plants were scouted and two sticky cards applied per plot weekly to record S. albicosta as well as beneficial insects found before and after insecticide application over four weeks. Finally, ten ears per plot were assessed at harvest to record the amount of feeding damage. Ear assessments showed heavy feeding damage to untreated control plots (90% of ears were infested with mean 11.1 ± 9.8 cm² of feeding damage per ear). All eight insecticide treatments significantly reduced mean feeding damage to corn ears. The insecticide that reduced feeding the least was Radiant (43% infested with mean 4.1 ± 7.2 cm² of feeding damage) and the best were Elevest and Besiege (8% infested with mean 0.6 ± 2.4 cm² feeding damage).