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Soybean Diseases

All Soybean Diseases Content

aerial view of South Dakota farm and surrounding land

Pest & Crop Newsletter

SDSU Extension publishes the South Dakota Pest & Crop Newsletter to provide growers, producers, crop consultants, and others involved in crop production with timely news pertinent to management of pests, diseases, and weeds in South Dakota.

Harvested corn field with field pennycress throughout.

Soybean Cyst Nematode Management Plans Should Include Proactive Weed Management

While soybean cyst nematode can be managed through use of resistant varieties and crop rotation, presence of alternative weed hosts can negate the benefits of these practices by providing a host for soybean cyst nematode to continue to accumulate in the soil.

Green cover crop growing within yellow wheat stubble.

Cover Crop Considerations When Dealing With Soybean Cyst Nematode

With the soybeans being harvested a little earlier than usual this year, some producers are finding themselves making management decisions that include cover crops. For soybean producers dealing with soybean cyst nematode in their fields, selection of cover crops is important since some of these can be hosts for soybean cyst nematode.

A map of South Dakota counties shaded to indicate the year for which the soybean cyst nematode was detected.

HG Type Testing: A Management Strategy for Soybean Cyst Nematode Control

Have you noticed lower soybean yielding areas in your field? Soybean cyst nematode may be to blame. Fall, and especially after soybean harvest, is the best time to sample soil and have it tested for soybean cyst nematode.

A soybean field showing plants in a circular pattern killed charcoal rot.

Scout for Charcoal Rot in Early Senescing Parts of the Field

The drought conditions in the past few weeks have led to some soybean fields senescing early. However, some of the early senescing may be due charcoal rot.

A soybean field with plants yellowing and dropping leaves in larger portion of the field while the rest of the field has green soybean plants.

Drought Stress or Stem Canker Killing Soybean Plants?

Several soybean fields scouted in a number of Eastern counties have plants dying or dropping leaves prematurely. While the majority of these fields have drought stress causing early senescence, a few fields have also stem canker developing

Left: A soybean plant with cotton white mycelia girdling the lower portions of the stem amidst healthy soybean plants. Right: A soybean field with some plants having yellowing leaves due to sudden death syndrome infection.

White Mold and Sudden Death Syndrome Starting to Develop

White mold and sudden death syndrome are starting to develop in a number of soybean fields. These two diseases develop starting at the soybean flowering growth stage and can occur throughout the rest of the soybean growing season.

soybean field with white mold

White Mold (Sclerotinia Stem Rot) of Soybean

Fact sheet of the symptoms and signs for while mold in soybean.

Soybean plant with with yellow-chlorotic blotches between leaf veins and noticable browning due to sudden death syndrome.

Sudden Death Syndrome of Soybean

Fact sheet discussing sudden death syndrome of soybean.

Left: Green soybean plants covered with yellow and brown spots indicative of frogeye leaf spot infection.  Right: Green soybean trifoliate that is covered in brown spots.

Deciding on Fungicide Application to Manage Mid-Late Season Soybean Leaf Fungal Diseases

Soybean leaf diseases can develop in some soybean fields to reach yield-reducing levels. The question that growers often ask is whether it is profitable to apply a fungicide to soybeans at the R3/R4 growth stage in South Dakota.