Consider soil testing for soybean cyst nematode
SCN is a parasitic worm that can cause 15 percent to 30 percent yield loss without above ground symptoms. The disease can be a ‘silent killer’. It is the #1 soybean disease in the U.S., and is spreading though North Dakota. It was first confirmed in Richland County (2003), followed by Cass (2007), Dickey (2009), LaMoure (2010), Ransom (2010), and Barnes (2010). SCN may take a few years (seasons of soybeans) to build up, but when it does, it is difficult to manage. As such, early detection of SCN is very important.
Soil testing is the best way to determine if you have SCN in your fields. Briefly, take a small soil probe, probe about 2 inches from the soybean plants, down 6-8”. Take maybe 20 cores, mix, bag, and send to that lab. In North Dakota, I would recommend sampling places that SCN is most likely to be found; namely, the field entrance, low spots, and near fences or tree rows.
I am including some links to youtube videos about SCN and soil sampling from states that have had the problem for some time, Iowa and Nebraska. These video will help you understand what SCN is, and the Iowa State video shows exactly how to soil sample. I am also including a link to a website with great SCN info, sponsored by the North Central Soybean Research Program, which is partially funded by the North Dakota Soybean Council http://www.planthealth.info/scn_basics.htm.
How to soil sample for SCN in the fall (9:19) – Greg Tylka – Iowa State University (very good & detailed) http://www.youtube.com/watch?v=W2GCGnOcGWs
Soybean Cyst Nematode Basics (3:47) – Loren Giesler – University of Nebraska (Covers the basics very well). http://www.youtube.com/watch?v=GLHTCSYkc5I&NR=1