Soybean cyst nematodes cannot be ignored

Farmers need to know the soybean cyst nematode levels in their fields. On-farm research in mid-Michigan revealed that resistant varieties can provide a major yield enhancement or a yield drag, depending on nematode population levels.

It has been 25 years since soybean cyst nematodes were first discovered in Michigan’s Gratiot County. Over the years, damage was easily diagnosed on low fertility, sandy type soils. Usually, the sites had a history of multiple back-to-back years of continuous soybeans. Resistant varieties have been used to help combat the pest.

That is not the end of the story. Soybean cyst nematodes can be found in all parts of the state on all types of soil. In 2012, all of the Michigan State University Extension on-farm soybean variety performance trial sites in Gratiot County were sampled for soybean cyst nematodes. One site planted with full-season varieties was found to have a moderately high soybean cyst nematode population level. This was a Parkhill loam soil with a good multi-crop rotation; it was not a site you would expect to find soybean cyst nematodes.

In this trial, both soybean cyst nematode-resistant and non-resistant varieties were present. Six of the varieties were sampled for soybean cyst nematodes separately both early in the growing season then again at harvest time. The nematode levels remained nearly constant where resistance varieties were planted. The cyst count increased five-fold and the egg and juvenile count increased 10-fold where non-resistant varieties were planted. Although visually it was difficult to detect a difference, the yield reduction of the non-resistant varieties averaged 8.4 bushels.

Two other sites where the same full-season varieties were planted had no or low soybean cyst nematode levels detected. At both of these sites, the non-resistant varieties out-yielded the resistant varieties by an average of 3.3 bushels. View the complete results.

The take-home message is simple: Know your fields and get them tested for soybean cyst nematodes. Plant resistant varieties only where they are needed, and adopt a recommended strategy to prevent soybean cyst nematodes or battle them if you become infected. Currently, the Michigan Soybean Checkoff program will cover the cost of nematode testing for up to 20 fields per farm.

To find out more about soybean cyst nematode management strategies or the sampling procedure, contact your local MSU Extension office.

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