Earlier this summer, I found aphids in V4 corn in central Iowa. This early establishment is unusual because most aphids that feed on corn have to migrate from the southern United States every summer. My lab also found soybean aphid in vegetative soybean at most of the Iowa State University Research Farms in June. Although they can overwinter in Iowa, larger colonies have not recently formed until after bloom. Pea aphids have also been reported in alfalfa in northeastern Iowa. All these aphid detections prompted me to summarize a few scouting reminders and treatment thresholds for aphids in field crops.
Available at: http://works.bepress.com/erin_hodgson/26/