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Soybean Diseases

All Soybean Diseases Content

Soybean leaves with several bright green lesions progressing into tears with brown crusting along the edges.

Bacterial Blight Common in Soybean Fields

Several soybean fields scouted the week of July 15, 2019 were found with bacterial blight developing. The frequent rains experienced in most soybean growing counties have led to the development of this disease. Bacterial blight affected leaves are most evident on younger leaves in the upper canopy.

A green soybean plant with purple and white flowers begining to develop.

Current Weather Conditions Are Conducive White Mold Development in Soybeans

Frequent rains and overcast conditions continue to occur in South Dakota’s main soybean growing counties. These conditions favor white mold development. In some of these counties, soybean is already at R1, which is also the best timing for fungicide application targeting white mold control.

A green soybean pod with frogeye leaf spot symptoms. The pod is partially open to reveal developing seed at the end of the pod with frogeye leaf spot symptoms developing.

Frogeye Leaf Spot of Soybean

This fact sheet is about a soybean disease that is increasingly becoming more severe in South Dakota. Moreover, fungicide resistance for this pathogen has been detected in South Dakota.

Alfalfa shoots with top leaves showing yellow patches interspersed with green patches, symptoms for Alfalfa mosaic virus

Alfalfa Mosaic Developing in a Few Alfalfa Fields

In South Dakota, alfalfa fields that were recently scouted were found to be infected with Alfalfa mosaic virus (AMV) at a very low incidence. AMV is a common virus in alfalfa that can also infect soybeans.

An empty grain bin full-air floor is plugged by insect webbing.

Stored Grain Pests: Spring Insect and Disease Issues

Grain storage is a key component in getting your crop to market. Aside from watching bins for spoilage, moisture, and temperature changes, make sure you are looking for signs of pest infestation.

Soybean seed drill. Courtesy: United Soybean Board

Fungicide Seed Treatment Considerations for 2019

With the excessive soil moisture and flooding that has occurred throughout South Dakota, growers may be thinking about using a fungicide seed treatment this planting season.

soybean pods

2018 Field Plot Summaries for Soybeans: Plant Disease and Fungicide Trials

This is a summary of soybean field research studies that were conducted in 2018. The purpose of these studies was to assess efficacies of fungicides for foliar disease management and nematicides/seed treatment products for nematode management. The studies were conducted on growers’ land in Brookings and Volga Research Farm.

Diseases & Disorders teaser

Fungicide Resistance: Risk and Management

What is fungicide resistance?
Fungicide resistance can be defined as when a pathogen population is no longer sensitive or has reduced sensitivity to the fungicide that used to control the same pathogen.

A patch of soybeans with several plants exhibiting browning and yellowing leaves.

Plant Disease Management Decisions to Make Before Planting

For most plant diseases, in-season management choices are very limited. In fact, there are no in-season management options available for diseases caused by nematodes, viruses, and bacteria.

green leafy plants

Soybean Vein Necrosis Virus Detected in South Dakota Soybeans

A new soybean virus called Soybean vein necrosis virus (SVNV) was detected in South Dakota soybean fields in Davison and Union counties. Symptomatic plants were sporadic and found along the field borders. Infected plants showed mild to moderate severity.