More than 80 percent of the Illinois soybean fields are infested with soybean cyst nematode (SCN) and fields should be sampled regularly for SCN populations. Those two points were made by Terry Niblack, Extension nematologist, at the recent University of Illinois Corn and Soybean Classic at Malta.

According to Niblack, three reasons that fields should be sampled regularly for the pest are:

· If the field has been SCN-free in the past, it probably won't be for long. SCN was first found in Illinois in one single county in 1962; by 2005 it had spread throughout all counties in the state.

· It is much easier to keep SCN numbers low than it is to drive high numbers down. Periodic soil sampling is the only way to know what is happening with the SCN population in a field. SCN can cause 30 percent or more yield loss without causing any visible symptoms.

· If the field is planted to a confirmed SCN-resistant variety and SCN populations are increasing, that's proof that adaptation or a "race shift" has occurred. SCN-resistant varieties do not have the same levels of resistance and there are no immune soybean varieties. The only way to know about the population of the pest is to sample and track population over time.

An important word in SCN management is "rotate". Rotate crops, rotate resistant varieties, and rotate source of resistance.

An assessment of varieties labeled "SCN-resistant" can be found in the booklet,

updated yearly, titled Variety Information Program for Soybeans (VIPS) and at the web site http://www.vipsoybeans.org/ These efforts are supported by the Illinois Soybean Association.

In addition to resistant varieties, experimental seed treatment products are being tested for their use in managing SCN. Currently, however, none have been released.

It is important to implement the message about SCN of several years ago, "take the test (soil test), and beat the pest (SCN)", concludes Niblack.

For more information about SCN and testing, contact your local University of Illinois Extension office. In Franklin County you may call Marc Lamczyk at (618) 439-3178, e-mail him at lamczyk@illinois.edu or visit www.extension.uiuc.edu/franklin .