Two ways to detect the presence of the nematode are to check plants during the growing season and to review yields after the growing season. Examining the roots will show the cyst, and a soil sample will confirm the infestation. Post-season yield review can indicate a pattern of fields or portions of fields that have declining yields or yields that fall short of the season's expectations. Byrnes says declining yields and visual symptoms indicate that SCN populations have reached damaging levels. Testing a soil sample can confirm the population level.
Soil samples can come from any field at any time from early spring to tale fall.
For management decisions, the best approach is to take soil samples in the fall, presumably from corn fields, before growing soybeans the following year. Where a producer confirms that SCN is present and has determined a population level, soybean variety selection is critical. The variety may have the yield potential, disease defensiveness and herbicide tolerance the producer wants. Eventually, however, SCN levels will grow to the point that they will be difficult to manage even with a SCN-resistant variety. The strategy Byrnes recommends is to plant a SCN-resistant variety where the presence of the pest has been confirmed.