FOLEY, Minn. — In the most recent IPM podcast for Field Crops, Dr. Dean Malvick, the University of Minnesota professor in plant pathology and extension specialist in corn and soybean diseases, spoke on late season corn and soybean pathogens. One late season soybean disease covered in this podcast was Sudden Death Syndrome also known as SDS.
SDS is a root disease caused by the soil borne fungal pathogen Fusarium virguliforme. This pathogen primarily infects soybeans however it may also infect dry edible beans and alfalfa. This fungal pathogen infects root systems as early as 2 to 4 weeks after planting. As this disease progresses, it produces a toxin that moves to the top of the plant producing yellow spots between veins of soybean plants. As this disease progresses, the yellow spots expand between the veins of the soybean leaf eventually creating brown lesions surrounded by yellow or chlorotic areas. The symptoms of SDS may sound like another soybean disease called Brown Stem Rot. However, two symptoms may be used to separate these two diseases apart in field. The first difference is SDS will cause root rot, whereas the root systems of soybeans affected by Brown Stem Rot remain relatively unaffected. The second symptom is found by looking at the pith of the lower stem. Soybeans affected by SDS will maintain a white color in the pith of the lower stem whereas soybeans affected by Brown Stem Rot will, unsurprisingly given the name, be a brown color inside the stem.
Yield losses due to SDS can range from 20% to 80% or more depending on severity of infection. With that being said, knowledge on current distribution of SDS throughout the state has confirmed the presence of the disease in the counties bordering south of Stearns County and has been confirmed in Benton County. Assistance with studying the distribution of SDS in Minnesota has been requested by Dr. Malvick and Stearns, Benton, and Morrison counties made that list. For growers willing to help, they are looking for 2-4 different fields from Stearns and Morrison Counties that display SDS symptomology in soybeans to take plant and soil samples. For growers in all three counties, collection of edible beans or alfalfa samples that display root rot and stunting or yellowing consistent with SDS infection have been requested. We would like these fields to be spread throughout these counties if possible. If you would like to participate and want more information please free to call the office at 320-968-5077. Samples will continue to be accepted until plants mature and turn yellow. Results will be shared with those who submit samples.
Conditions that favor this disease are early planting, cool and wet soils, susceptible varieties of soybeans and fields with Soybean Cyst Nematodes (SCN). Keeping in mind that SCN is the most significant pathogens of soybeans, I still have sample bags to test fields for SCN. Again for more information on that program please call the office at 320-968-5077. Finally, management tactics for SDS involves planting varieties that have a high resistance to SDS and SCN, delaying planting until soils are warmer, limiting soil compaction, and proper drainage.
On a final note, the annual Beef Field Day in Morrison County is Tuesday, September 11th at 5:30pm. The Tour will be hosted at Berg’s Red-Tail Ranch and is located at 10484 170th Avenue in Little Falls. This is a great opportunity for local producers and agribusinesses to learn more on rotational grazing, interseeding pastures, soil health, silvopasture, genetics, and management for meat quality, and will include the background and history of the Red-Tail Ranch. Preregistration is not required but is encouraged to help with the meal count. If you have any questions or would like to preregister call Emily Wilmes at the Stearns County Extension Office at 320-255-6169 extension 3.
— Nathan Drewitz, University of Minnesota Extension
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