MSU Extension

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

This will be the fourteenth consecutive year the Michigan Soybean Promotion Committee (MSPC) has sponsored the soybean cyst nematode sampling program in partnership with Diagnostic Services at MSU. Like many new programs, it got off to a rather slow start as only 73 samples were submitted for soybean cyst nematode analyses in 1996. However, only two years later, 904 samples were sent to the lab and typically we receive over 1,000 annually. Soybean growers caught on very quickly to the benefits of this program. The samples are paid by check-off dollars and the results are used to make sound soybean cyst nematode management decisions. Soybean cyst nematode is major limiting factor in soybean production and accounts for over two billion dollars of losses worldwide on an annual basis. It should not be ignored.

Last year, we saw a 35 percent decline in the number of soybean cyst nematode samples submitted to Diagnostic Services. We hope this represents just a small blip in our data and isn’t the beginning of a trend. Growers should continue to monitor soybean cyst nematode population densities on their farms even if they are fully aware the nematode is present.

Of concern is a failure to sample fields where soybean cyst nematode-resistant soybean varieties were grown. Yields are always monitored and, of course, yields should meet growers’ goals especially when growing soybean cyst nematode-resistant cultivars on infested sites. However, soybean cyst nematode numbers should also decline from planting to harvest under a good resistant variety. The only way to obtain this information is by sampling. If you notice soybean cyst nematode numbers increasing on your resistant varieties, it is time to change things up a bit. Populations of soybean cyst nematodes will adapt fairly quickly, so it is important to monitor their numbers to avoid extreme increases in their population densities. If you develop a type (race) of soybean cyst nematode that has overcome the source of resistance you use most often, achieving good yields will become much more difficult.

Virtually every county south of Clare is infested with soybean cyst nematode. Soybean cyst nematodes are typically detected in 60-65 percent of the samples submitted through the MSPC-sponsored sampling program. In some of our major soybean producing counties such as Monroe, Saginaw and Shiawassee, four out of every five samples usually contain soybean cyst nematode. However, in many of our counties, soybean cyst nematodes are not yet widely distributed, and it should be the goal of growers in those counties to avoid infestations for as long as possible. To accomplish this strategy, sampling is critical. It is still strongly recommended all fields are sampled for soybean cyst nematode the fall prior to growing soybeans. Since soybean cyst nematodes, like all plant-parasitic nematodes, are microscopic, the only way to assess their population densities is to collect soil samples and submit them to a nematode diagnostic lab for counts.

One of the most egregious mistakes a soybean grower can make is choosing to sow a soybean cyst nematode-susceptible variety in a field where a resistant variety should have been grown. In this situation, yield will potentially be cut in half and nematode numbers will potentially increase dramatically. Soybean cyst nematodes are easier to manage and high yields easier to obtain, if nematode numbers are kept in check. Once again, regular soil sampling goes a long way toward reducing or eliminating serious risk of yield loss to soybean cyst nematodes.

If you wish to sample for soybean cyst nematodes, soil samples should be sent to Diagnostic Services (www.pestid.msu.edu). Every sample should be accompanied by a special “Take the Test, Beat the Pest” soybean cyst nematode form. They can be obtained at your county office or by contacting personnel within the Michigan Soybean Promotion Committee office in Frankenmuth. The normal fee for a nematode analysis is $25but this fee is waived by using this form. There is a limit of 20 samples per grower per calendar year (if you exceed this limit, you will be assessed the $25fee for every sample over 20).

Don’t let soybean cyst nematodes rob you of your yield, be sure to take advantage of this program. It’s free and in these tough economic times, isn’t that a good thing.