Impact of the Early Soybean Production System on Arthropod Pest Populations in Georgia

The early soybean production system (ESPS) in the southern region of the United States is being promoted as a cropping practice that reduces the risk of drought stress to the crop. This ESPS involves planting an early-maturing soybean cultivar, ≈4–6 wk before planting the conventional later-maturing soybean cultivars. A field study was conducted in Georgia soybeans in 1997–1999 to compare arthropod pest seasonal abundance, insect-induced defoliation, and yields between ESPS and conventionally planted soybeans. The conventional soybean production system had higher populations of late season defoliators, including the velvetbean caterpillar, Anticarsia gemmatalis Hübner, and the soybean looper, Pseudoplusia includens (Walker). The percentage defoliation was higher in the conventional system than in the ESPS all three years. The threecornered alfalfa hopper, Spissistilus festinus (Say), was more abundant in the ESPS in early season, but similar population densities were observed in July–August in both ESPS and conventional soybeans, then the highest seasonal population peaks occurred in the conventional soybeans in September, after the ESPS was harvested. Stink bugs, primarily the southern green stink bug, Nezara viridula (L.), also were more numerous in the ESPS during midseason. However, stink bugs moved to the conventional soybeans in September and peaked at densities much higher than in the ESPS. Yields in the ESPS plots were equal to or exceeded the yields in the conventional soybean plots in all three years of this study. Adoption of ESPS in the southern region should have a positive economical and environmental impact on soybean integrated pest management because this system escapes serious crop injury from some annual insect pests.