Dr. Rishi Burlakoti
Weather INnovations Consulting LP, Chatham
Sudden death syndrome (SDS), a widespread soil-borne disease in Ontario, was observed last week in soybean fields in southwest Ontario. The disease is caused by the fungus Fusarium vilguliformis. The fungus survives in crop residues and soil for several years. The fungus infects soybean plants in its early stages, however, the symptoms do not appear before late flowering to early pod filling. The probability of SDS incidence is high in fields infested with soybean cyst nematodes.
How to Identify Sudden death syndrome?
Death Syndrome
Foliar symptoms: Scattered yellow spots occur initially between veins in soybean foliage. Once the disease progresses, the spots change to yellow and brown blotches between the leaf veins, but mid veins and lateral veins remain green (Fig. 1). In advance stages of disease, the entire plant wilts. SDS symptoms appear in patches in the fields where soil moisture and compaction is high. The foliar symptoms of SDS and brown stem rot (BSR) are similar; however, the symptoms between them can be distinguished by observing the internal stem. The pith of stem is white in SDS infected plants, whereas BSR infected plants produce brown discoloration in the pith.