Believe it or not, the #1 soybean pest in the United States is the Soybean Cyst Nematode (SCN), which causes estimated annual losses of up to $1.28 billion (128.6 million bushels). What makes this pest even more troublesome is that yield reductions commonly occur without any visible aboveground symptoms. Soil sampling is the most accurate way to determine the presence and abundance of SCN in your fields. The best time to test for SCN is after harvest in the fall. This will give enough time to plan a management strategy for the next growing season.

How to Collect Soil Samples for SCN Testing
SCN samples collected in the fall can be taken similarly to soil fertility samples. Since SCN is not evenly distributed throughout a field, collect the cores in a zig-zag pattern across the area of the sample. A collection of several cores at a depth of 6-8″ is sufficient, and a single sample should not represent more than 20 acres. One pint of soil is enough for most labs to perform the test. Once collected, place the sample in a normal soil sample bag and send to the lab as soon as possible.

Table 1. SCN Management Guidelines Based on SCN Egg Counts

Key Management Strategies

• Test your fields to determine population levels.
• Rotate to non-host crops.
• Variety selection – Rotating to a different source of SCN resistance.
• Utilize a nematode-protectant seed treatment.

Where to send samples for analysis; click for websites:

• University of Missouri SCN Diagnostics
• University of Illinois Plant Clinic
• Kansas State University Plant Diagnostic Lab
• Iowa State University Plant Diagnostic Clinic
• Midwest Laboratories

Also, check with your local university extension and state soybean association representatives. The United Soybean Board regularly offers up to two free SCN tests to growers through these organizations.