The soybean cyst nematode (SCN) was first discovered in Iowa more than 35 years ago, in Winnebago County in 1978 to be specific. The nematode is widely considered to be the most damaging pathogen of soybeans in Iowa. Results of random surveys of the state funded by the soybean checkoff and conducted in the
If SCN infestations are discovered in fields when nematode population densities are low or moderate, SCN populations can be kept in check by growing SCN-resistant soybean varieties in rotation with nonhost corn. Also, there are now nematode-protectant seed treatments that can be used when resistant soybeans are grown. Because SCN is widely distributed across Iowa, any field in which soybeans are grown should be checked for the presence of SCN.
Check below ground to be sure
Soybean plants often do not show obvious aboveground symptoms of damage when SCN numbers are low or moderate. It is important to look below ground to check for SCN during the growing season.
To scout for SCN, dig roots and look for the presence of SCN females. The SCN females will appear as small, white objects that are about the size of a period at the end of a printed sentence.
SCN females first appear on soybean roots about 30 to 35 days after planting, and then can be found on roots throughout the remainder of June, July, and into early to
SCN can be found in soil samples, too
Another effective way to check fields for SCN is to collect soil samples. Multiple 1-inch-diameter, 8-inch-deep soil cores should be collected from a sampling area in the field. Many private soil-testing laboratories can process soil samples for SCN. Samples also can be sent to the Iowa State University Plant and Insect Diagnostic Clinic to be tested for SCN. More information about soil sampling for SCN is available in this ICM News article.
Source: Greg Tylka, Iowa State University
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