Scout fields now for soybean aphids

Soybean aphid populations are increasing in some fields in northeastern and central Iowa. Brian Lang, ISU field specialist-crops, reports that soybean aphids have increased dramatically during the past 2 weeks near Decorah. He found the first aphids on June 5 in soybean planted May 13. To give you a perspective of the increasing population, in his research plots, the average aphid density per plant for the past 4 weeks was 10 (June 16), 100 (June 22), 315 (June 30), and 640 (July 6). For soybean that was protected with a seed treatment, aphid populations on July 6 averaged 32 aphids per plant, or 95 percent less than the untreated plants. Palle Pedersen, ISU extension agronomist, also has found aphids to be abundant on some plants near Ames