Evaluation/Refinement of Fall Armyworm, Spodoptera frugiperda (J.E. Smith), Thresholds, in Mississippi Whorl Stage Field Corn and Grain Sorghu

During 2016 and 2017, studies were conducted to determine the effects of Spodoptera frugiperda (J.E. Smith) on both damage and yield of Sorghum bicolor (L.) Moench and Zea mays (L.) when infested during the whorl stage. Results from damage ratings suggest that as the amount of overall plants infested increased, overall damage rating increased. However, yield results suggested that there was no yield loss as percent infested plants increased. Other studies were conducted to determine the most sensitive vegetative growth stages of grain sorghum and field corn. Manual damage studies suggests that extensive damage to field corn during growth stages V9 to V15 will cause significant yield loss. Also, damage to grain sorghum after growth stage V8 and prior to boot stage can cause significant yield loss.