David Owens, Extension Entomologist, owensd@udel.edu and Bill Cissel, Extension Agent – Integrated Pest Management; bcissel@udel.edu
Continue scouting for defoliators and for pod feeding insects. Primary defoliators are green cloverworm, bean leaf beetle, and Japanese beetles. A few more aphids have been found in fields throughout the state, but only isolated colonies. As a reminder, defoliation the threshold in reproductive stage soybean is 15%, and for aphids the threshold is 250 aphids per plant. Stink bugs are generally present in low numbers in R-stage beans, thresholds are 5 bugs per 25 sweep sample. Take multiple samples throughout the field because stink bugs aggregate. A small number of brown marmorated stink bugs have been found so far, this is an edge species that usually does not move into field interiors; check near woodlines, especially those that have tree of heaven. The high humidity has favored pathogens of spider mites. A few hotspots we have visited in the last week have had alarming visual symptoms of mite defoliation, but close inspection revealed that all the mites were dead. Recent humid weather favors fungal pathogens and in some fields, predatory mites have moved in. Dead spider mites will look brown and fuzzy. Predatory mites will be a creamy white to pale orange color, pear shaped, and with no spots or markings. As a heads-up, soybean looper is active in South Carolina. It usually appears in our area near the end of August.