Written by Dean Malvick, UMN Extension plant pathologist
We are working to understand the distribution of the fungal pathogen that causes soybean sudden death syndrome and root rot of edible bean in Minnesota. Your help is requested in the collection of plant samples to enable us to determine where this pathogen/disease is spreading.
We are focusing our sampling on areas north of Highway 12. Thus, we are interested in soybean samples with foliar symptoms of SDS as well as dry edible bean and alfalfa samples with symptoms of root rot from Northwest and Central MN.
The soilborne fungus (Fusarium virguliforme) that causes sudden death syndrome (SDS) of soybean and root rot of edible bean and other legumes is spreading north in Minnesota. Symptoms of SDS on soybean include interveinal necrosis & chlorosis, defoliation which leaves petioles attached, and root rot (Figures 1 & 2). Our goal is to monitor and map the presence of this pathogen in soybean, dry edible bean, and alfalfa production fields across northern Minnesota.
Fig. 1. Symptoms of SDS at the early stage of
development on soybean leaves
Fig 2. Symptoms of SDS at the late stage of
development on soybean leaves.
Laboratory tests will be used to detect the presence of Fusarium virguliforme in the submitted samples. In the winter we will report detection of this pathogen and SDS by county. Locations and results for specific fields will be shared only with the individual who submitted the sample.
How to take plant samples
Follow these sampling steps for detection and diagnosis of the fungal pathogen that causes soybean SDS and root rot of other legumes. Please collect samples by the first week of September.
- Collect 4-6 plants showing SDS leaf symptoms, yellowing, or root rot from individual fields.
- Photograph the plant symptoms in the field.
- Dig up the root system, cut off shoot 8-10” above soil line, and place roots in plastic bag wrapped in moist paper towel, leaving stem sticking out of bag.
- For soybean, also send at least three sets of trifoliate leaves showing symptoms. Leaves should be wrapped in paper.
- Please include this information for each sample site: county, nearest town, GPS coordinates, description of symptoms and distribution in field, crop variety if known.
- Please ship as soon as possible after collection and send package to Dean Malvick, 1991 Upper Buford Cir, 495 Borlaug Hall, St Paul, MN 55108. Or, contact Dean Malvick by email (dmalvick@umn.edu) to receive a prepaid FedEx label to use for shipping ASAP.
