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Scout for Late-Summer Soybean Diseases

Jul 08 2021

The dog days of summer will be here soon. At this time of the season, the bulk of crop protection applications are complete and harvest is only a few months away. Use this opportunity to do some late-season scouting in your customers’ soybean fields.

In July and August, it’s a good idea to look for disease symptoms, specifically. Even if it’s past the application window for certain solutions, you can use the information you gather to improve your growers’ future plans.


When scouting for disease in soybean fields, we recommend looking for symptoms on the lower leaves and stems, working your way up the plant.

Sudden death syndrome (SDS), is one disease that usually shows up in late summer. The symptoms start as yellow spots on leaves that transition to yellow patches, which eventually turn into brown dead tissue. You also can check the roots for bluish spore masses.

Corteva fungicide

Once SDS shows up in a field, it generally spreads to larger areas in future seasons, which can end up hurting yield. Foliar fungicides are not effective in controlling it. However, if you find SDS, you can help your customer choose resistant varieties or seed treatments that include a fungicide.

Other diseases like white mold and frogeye leafspot can show up later in the summer as well. These can take a bite out of yield if left to flourish. A foliar fungicide like Aproach® Prima can control many such diseases and you can apply it curatively. However, if you did not apply a fungicide preventively this year and if you do find symptoms, that may be a sign to do preventive spraying next year.

As you scout, make sure to keep good notes and take photos of any issues you find. Save this data and be sure to go over it with your customers as you start planning for next year. You and your customers can also download the Disease ID Guide from Corteva Agriscience to help keep track of an disease symptoms in their fields.