Roberto J. Cordero

Field Efficacy of Insecticides for Control of Lepidopteran Pests on Collards in Virginia

Control of lepidopteran pests on collards (Brassica oleracea L. Acephala group) can be challenging because the leaves are the marketable portion of the crop and because of insecticide resistance problems in diamondback moth, Plutella xylostella (L.). In 2003 and 2004 in two locations of Virginia, field efficacy tests were conducted on several conventional standard insecticides as well as several new and more IPM-compatible insecticides (applied at their lowest-labeled rates) for control of lepidopteran pests in collards. Lepidopteran pest species included the following (in relative order of abundance): P. xylostella, Pieris rapae (L.), Trichoplusia ni (Hubner), Spodoptera frugiperda (J. E. Smith), Estigmene acrea (Drury), S. exigua (Hubner), Helicoverpa zea (Boddie), Evergestis rimosalis (Guenee), and Hellula rogatalis (Hulst). The most efficacious insecticides over the five experiments included acephate, emamectin benzoate, esfenvalerate, methomyl, methoxyfenozide, novaluron, indoxacarb, and spinosad. Although acetamiprid, Bacillus thuringiensis subsp. kurstaki, and azadirachtin have shown efficacy against lepidopteran pests in other studies, they were inconsistent in their performance in these experiments. Insecticide options that provide reliable control of the suite of lepidopteran pests that attack collards in Virginia, and that are relatively less toxic to natural enemies and thus can fit well into integrated pest management programs include indoxacarb, spinosad, novaluron, emamectin benzoate, and methoxyfenozide.