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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.

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.

Green soybean plant with white mold present on the stem and pod.

Start of Flowering Is the Ideal Time for White Mold Management in Soybeans

Some early planted soybeans are starting to flower (R1 growth stage). One soybean disease that needs to be managed at this growth stage is white mold.

A soybean root with several small white cysts growing on it.

Soybean Cyst Nematode in South Dakota: History, Biology, and Management

Factsheet about Soybean Cyst Nematode history, biology and management in South Dakota