How to Scout for Aphids and Protect Your Crops

Soybean aphids are small, sap-sucking insects that can be a major pest of soybeans. They are typically found in the upper leaves of soybean plants, and they can quickly multiply and cause significant damage.

In recent years, soybean aphids have been relatively quiet in Iowa. However, there have been isolated fields in northern Iowa this year that have exceeded the economic threshold for soybean aphids. This means that the aphid population is high enough to cause economic damage to crops.

Farmers are urged to scout their fields now for soybean aphids. Speed Scouting is a quick and easy way to assess soybean aphid pressure. It involves counting the number of aphids on 11 plants in each 50-acre area of soybean. If there are 40 or more aphids on any of the plants, the field should be treated.

Insecticide resistance is a concern with soybean aphids. Some populations of soybean aphids have developed resistance to pyrethroid insecticides. If you have a history of using pyrethroids to control soybean aphids, you may want to consider using an insecticide with a different mode of action.

By scouting their fields now and taking appropriate action, farmers can help to protect their soybean crops from soybean aphids.

Tips for managing soybean aphids:

• Use a product labeled for soybean aphid, and use high volume and pressure so that droplets make contact with aphids on the undersides of leaves. Check aphid populations three days after application to assess product efficacy.

• Alternate the mode of action if soybean aphid populations need to be treated twice in a single growing season. Be aware of PHI (pre-harvest intervals) for applications made now.

• Understand that late-season increases in aphids, particularly after R5, may not impact yield like it does during early reproductive growth stages. A foliar insecticide applied after seed set may not be a profitable choice. By following these tips, you can help to manage soybean aphids and protect your crop yield.

For more information on aphids, visit our sister site Farms.com Field Guide pages: https://www.farms.com/field-guide/pests/aphids.aspx.

Photo Credit: gettyimages-gilaxia