Corn earworm is historically the most yield limiting pest in North Carolina soybean production. The robust threshold recommendations that were developed to effectively manage this pest were developed with determinate soybean varieties, however the adoption of indeterminate varieties produced in this state increases every year and what is now needed is robust recommendations to manage this pest in indeterminate soybean varieties. This need is especially critical as seed companies develop indeterminate soybean varieties in maturity groups where this growth habit has been traditionally unavailable (=MG5). Preliminary work indicates that corn earworm management thresholds likely should not vary between determinate and indeterminate varieties. However, infestation timing might differ, since corn earworms prefer to lay eggs in flowering beans and since indeterminate varieties flower over a longer time period than determinate varieties. This could result in scouting for earworms longer in indeterminate varieties and potentially needing to retreat some fields. The proposed research seeks to determine if corn earworm infestation timings vary for the indeterminate soybean varieties now being produced more widely across the state relative to determinate varieties. We will continue
to explore if thresholds should vary for determinate and indeterminate soybean varieties. This proposed research will support a graduate student in the NC State Entomology Program and will be conducted from 2021-2023. The impact of corn earworm pressure will be quantified with both a determinate and indeterminate soybean varieties. Data collected will include: corn earworm eggs number, corn earworm larvae number, soybean maturity, and soybean grain
yield. The proposed research will provide foundational management information for corn earworm in indeterminate soybean varieties in North Carolina and will be part of comprehensive management recommendations targeting indeterminate soybean varieties developed by the NC State Soybean Extension Team.