By Janet J. Knodel
Extension Entomologist
Time to start scouting for soybean aphids. The IPM scouts in North Dakota and Minnesota found soybean aphids in 42% of the soybean fields surveyed. Percentage of plants infested with soybean aphids ranged from 0 to 90% with an average of 32% of plants infested. The average number of soybean aphids per plant ranged from 0 to 31. Soybean aphids are usually found on the underside of the leaves and in the top part (newest growth) of the plant during the vegetative and early reproductive growth stages. Other symptoms include the presence of lady beetles and other predators that feed on soybean aphids; or sticky, glossy ‘honey dew’ that is excreted by the soybean aphids as they digest the sugars from plant juices. Regular scouting will help monitor populations of soybean aphids and improve timing of an insecticide application at the economic threshold (average of 250 aphids per plant and 80% of the plant infested). The USDA NASS reports that 22% of the soybeans were blooming (R1) in North Dakota (USDA NASS News Release – July 6, 2015).
