Soybean aphids are tiny, sap-sucking insects that cause yield loss when present in large numbers (several hundreds). Yield loss is greatest when aphids are present during R1 to R4 growth stages when blooms and young pods are more susceptible to stress. Depending on environmental conditions, aphid populations vary from year to year in SD. Proper scouting and management decisions need to happen in order to minimize yield losses in your soybean field.

Scouting should occur in late June or early July, before soybean plants start to bloom and continue through pod fill. Check 20 to 30 plants across the field to determine if action should be taken. The action threshold is 250 aphids per plant average.

Management of aphids:

  • Biological control – have the natural enemies control aphid numbers (pick targeted insecticides)
  • Insecticides – very effective foliar applications available to control aphids
  • Integrated Pest Management
  • Choice soybean varieties that have aphid resistance

Soybean Aphid Field eGuide