Soybean Cyst Nematode
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Soybean Cyst Nematode (SCN) is the number one contributor to yield loss in soybean crops nationwide, causing an estimated $1.2 billion dollars in damage annually. This pest has been detected in 71 counties in Ohio, with the highest concentrations located in the northwestern part of the state where soils tend to be sandy in content.
Symptoms: Significant yield reduction may take place with absolutely no above-ground symptoms. This is one of the main reasons you should sample fields for the presence and abundance of SCN.
Symptoms of SCN injury can easily be confused with other problems such as nutrient deficiencies, herbicide injury, disease, poor drainage, etc. The presence of oblong areas of stunted, yellowed plants is suggestive of SCN damage. Symptoms are generally more pronounced when soybean plants are under stress from such conditions as drought, low fertility, or compaction. Infected plants have poorly developed roots and very few Rhizobium nodules.
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Early in the growing season (6 weeks after planting), close examination of the roots may also reveal small, white to yellow spheres (bodies of female nematodes) attached to the root surface. These females are not much bigger than grains of coarse sugar, and should not be confused with the much larger Rhizobium nodules.
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Lifecycle: In the early life stages, SCN is a microscopic (1/64 inch long) roundworm that feeds on soybean roots. There are three major life stages of cyst nematodes: egg, juvenile, and adult. In Ohio, the life cycle can be completed in 24 to 30 days under favorable conditions. It is possible to have three to five generations (complete life cycles) each growing season.
Management Options:
Step 1: Collect soil samples to identify the fields that have cysts and monitor egg populations.
Step 2: Rotate crops
Step 3: Use resistant soybean varieties/seed treatments wisely.
Step 4: Use best management practices.
Step 5: Manage other diseases.
Step 6: Prevent introduction.