Tolerance to Stalk and Ear‐Invading Worms and Yield Performance of Bt and Conventional Corn Hybrids

European corn borer (ECB, Ostrinia nubilalis Hübner) and corn earworm (CEW, Helicoverpa zea Boddie) are important yield‐reducing insect pests of field corn (Zea mays L. var. indentata) in the northeastern United States. Transgenic hybrids bioengineered to express insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have revolutionized methods to control these caterpillars and other insect pests in corn. However, corn producers are faced with two decision‐making challenges every year: selection of the most appropriate Bt hybrids for the targeted pest complex from a large list of commercially available hybrids, and finding competitively yielding conventional hybrids for the required refuge hectare. This study was conducted at five sites across Maryland for 3 yr to evaluate more than 100 hybrids representing six Bt trait groups (three single‐protein and three multi‐protein genes) and a conventional non‐Bt group for their relative susceptibility to lepidopteran feeding injury and yield performance. Conventional hybrid tolerance to ECB injury or CEW ear damage and their yield varied each year except Dekalb DKC61‐22, which consistently produced greater yield than other non‐Bt hybrids. Injury caused by ECB was not found among any of the Bt hybrid groups. Hybrids with multi‐protein Bt traits showed greater ear protection than those with single‐protein Bt traits, but this improvement was small. Genuity VT3 Pro and Agrisure Viptera 3111 hybrids had the best ear protection and yield performance among the six tested Bt traits.