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Soybean Diseases

All Soybean Diseases Content

soybean pods


SDSU Extension is your partner to increase yields and improve efficiency.

aerial view of South Dakota farm and surrounding land


During the growing season, SDSU Extension provides weekly production recommendations.

Hand holding a dead early-planted soybean seed.

Risks of Early Soybean Planting in South Dakota

Early soybean planting offers potential yield benefits, but it also poses some risks. Learn some expert tips and considerations for early soybean planting this growing season.

A portion of a soybean field with soybean plants maturing with the soybean leaves turning yellow with the leaves and stems drying down.  The plants in the middle of the picture were also found with charcoal rot.

Charcoal and Fusarium Rots Observed in Early Senescing Soybean Plants

The drought conditions in South Dakota have led to early soybean senescence in some areas. However, some of the early senescing may be due to dry-season diseases, such as charcoal and Fusarium rots.

Young farmer examining soybean plants n a field at sunset.

Be Aware of Fungicide Resistance in Field Crops

A few soybean and corn fields have received or will be receiving a fungicide application this season. We recommend scouting fields treated with fungicides to determine if diseases are controlled as expected or if there are signs of reduced sensitivity.

Green soybeans with yellowing throughout.

Bacterial Blight Developing In Some Soybean Fields

Bacterial blight was found developing in a few soybean fields scouted the week of July 19. Leaf tattering is a common symptom of bacterial blight and happens when expanding bacterial blight lesions coalesce and form large brown patches.

A soybean plant with wilting leaves due to stem canker surrounded by healthy soybean plants.

Stem Canker Developing in Some Soybean Fields

A few soybean fields are showing some wilting plants due to stem canker. The field entries and head rows are the most-impacted parts of these fields. The current dry conditions are stressing the plants and causing early development of the disease.

Three bean leaf beetles. From Left: Brown beetle with black spots on a green leaf. Yellow beetle with black spots on a green leaf. Red beetle with black spots on a green leaf.

Monitor Soybean for Bean Leaf Beetle Activity

Some of the bean leaf beetles we are currently observing in South Dakota may make up the population of overwintering adults. While these adults are in soybean, they can cause significant amounts of defoliation to the leaves.

Three soybean fields with yellowing issues due to potassium deficiency, iron deficiency chlorosis and soybean cyst nematode.

What Is Causing Soybeans to Yellow at This Time?

Recently scouted soybean fields were observed with yellowing plants, and one field was found to have plants dying prematurely. Learn some of the factors that may cause soybean plants to yellow at this time in the growing season.

A soybean field showing healthy soybean plants, but roots are infested with SCN. The top right corner has an in-set picture that shows a soybean root with white pear-shaped SCN female cysts.

Drought Conditions May Increase Soybean Cyst Nematode Population in Soil

Moisture stress coupled with above-normal temperatures have been linked with increased soybean cyst nematode populations in the soil. In order to keep populations in the soil below the yield-reducing levels, there are a few management practices which can be used.