Following are some general soil sampling guidelines for this purpose.

  • The more soil cores collected and the smaller the area sampled, the more accurate the results will be.
  • Soil cores should be from the upper 8 in. of soil.
  • If corn or some other nonhost crop was last grown in the field, it doesn’t matter if soil cores are collected in the previous crop’s row.
  • It is better to collect soil cores after the previous corn (or other nonhost crop) rows have been destroyed by tillage.
  • If soybeans were last grown in the field, collect soil cores from under the old crop rows.
  • If sampling conventionally (not grid sampling), collect 15-20 soil cores in a zigzag pattern from no more than 20 acres. The 20-acre parcels of the field do not need to be square or rectangular; samples can be collected from zones according to the agronomic features of the field (see related gallery).
  • If grid sampling: collect one or two extra soil cores from every grid cell sample and combine these extra cores from the number of cells that represent approximately 20 acres.

Many private soil laboratories can process soil samples to determine SCN egg population densities. Samples also can be sent to the Iowa State University Plant and Insect Diagnostic Clinic, Room 327 Bessey Hall, Iowa State University, Ames, Iowa 50011-1020.  The current fee for SCN analysis at the ISU clinic is $15/sample for samples from Iowa. Samples sent to the ISU clinic should be accompanied by a completed (pdf) Plant Nematode Sample Submission Form.

More information about the biology, scouting, and management of SCN can be found at www.soybeancystnematode.info.