Effects of tobacco budworm (Lepidoptera: Noctuidae) infestations on pod damage and yield loss in soybean [Heliothis virescens]

Field plot studies from 1977 to 1980 were conducted to determine the effect of Heliothis virescens infestation on soybean. Larval infestations were established at various levels and times by applying eggs in a spray. The amount of damage and its effect on yield depended on the timing as well as the intensity of infestation. The only infestations that reduced yield were produced by egg application during full bloom. Resultant larvae were fifth or sixth stage during the full pod growth stage. They destroyed more seed than comparable larvae during other plant growth stages. The period during soybean bloom when egg application resulted in this critical synchrony was 1 week long.