November is the time for seed sales advertisement, no doubt about it. In our rush to learn all we can about new pest threats to the soybean crop sometimes we forget that the most yield improvement may well be made by dealing with our endemic pest problems. I'm talking in particular about Soybean Cyst Nematode (SCN). Our chronic yield losses from this pest aren't going to go away just because the new kid on the block 'rust' showed up. In Illinois over 80% of the fields are infested with SCN. Managing this pest with the right selection of a SCN resistant variety in affected fields is definitely in your best interest.

So, most of the soybean farmers in Illinois have a SCN problem, but the problem may not be exactly what they think it is. They know, for example, that when SCN numbers are high, plants are stunted, yellow, and yield poorly. They know that planting SCN-resistant varieties will help them recover yields and maybe reduce SCN levels. But how many farmers with SCN-infested fields know that SCN can reduce yields 15 to 30% without causing any stunting or yellowing. How many farmers know how SCN is affecting their ability to manage other problems in soybean fields, such as weeds, insects, and disease-causing microbes? SCN is a disease that can be managed but it takes some pre-planning and proper seed selection.

Don't know if you have SCN or don't know what your population numbers are? Well, sampling fields that will be planted to soybean in 2007 is best done right now in the fall. A soil sample should be a composite of 20 or more cores taken in a zigzag pattern across a field. Our U of I Extension nematologist Dr. Terry Niblack indicates that one sample can adequately represent a 5-acre area. That may seem daunting, so, what do you do if the field is 300 acres? Niblack recommends collecting samples from two or more arbitrarily selected 5-acre sections that represent similar soil types and crop histories. There's no need to sample the entire field unless you're planning to plant different varieties in different sections of the field. Excellent instructions for sampling are available at http://www.planthealth.info/scn_scout.htm.

Your samples can be sent to a private nematode testing lab or to the University of Illinois Nematology Lab, Department of Crop Science, AW101 Turner Hall, Urbana IL 61801. Two types of testing can be done. First, a standard population count. This tells you if you do have the nematode and how high that population may be in the field. A second kind of test can also be performed called an HG type test. This test is not necessary for everyone. If a producer has been managing SCN but just doesn't seem to be making any progress against it then that's who would benefit from an HG Type test which will characterize the actual population in the field.

Advances in the understanding of SCN have led to several important refinements of how to detect, monitor and manage SCN in your fields. Taking these steps for variety selection will take some of the pest risk out of next year's soybean crop.