Growth Stage-Based Management of Insects and Diseases in Mungbean in the U.S. Midwest Production

Mungbean (Vigna radiata L. Wilczek) is a warm-season legume native to the Indo-Myanmar region. In North America, it is adopted as a rotational or double crop due to its agronomic versatility, though cultivation remains limited. The extent to which mungbean production is constrained by insect and disease pests in the U.S. is unclear. Field experiments were conducted in 2023 and 2024 in Story County, Iowa, to assess the effect of fungicide and insecticide application timing on disease severity, defoliation, pod abortion, and yield. Two cultivars, Berken and OK2000, were evaluated. A tank mix (mefentrifluconazole + fluxapyroxad + pyraclostrobin and lambda-cyhalothrin) was applied at five reproductive stages from beginning flower (R1) to beginning maturity (R5) in a two-factorial randomized complete block design. Plots were inoculated with Septoria glycines and Cercospora sojina to simulate disease pressure. Applications at beginning pod (R2), beginning seed filling (R3), and full seed (R4) significantly reduced disease and pod abortion while protecting yield. Linear regression analyses identified insect-induced pod abortion as the primary driver of yield loss (adjusted R² = 0.30), with a moderate inverse correlation (r = –0.56) between pod loss and yield. These results highlight the importance of pesticide application timing, particularly at R3, to protect mungbean yield. Future research should identify the specific insect pests responsible for yield reduction.