Greg Tylka, plant pathologist, Iowa State University, provides the following guidelines for collecting soil samples to determine whether your fields are infected with nematodes:

  • Collect 15 to 20 12-in.-deep soil cores from the root zone of corn plants showing symptoms.
  • Collect four root masses.
  • Place soil cores in a sealed plastic bag; roots can be placed in a separate plastic bag.
  • Protect the samples from temperatures above 80°F.
  • Place samples gently in your vehicle.
  • Send samples to a lab as quickly as possible.

University plant diagnostic and private labs can help determine the species of nematodes affecting your fields and provide a good idea of the pest populations you have.

Because of the dry weather in parts of the Midwest in 2010, nematodes may have moved deeper into the soil. This could make sampling a bit more difficult this year.

Sampling can generally be done at the V6 to V8 stage in the early corn-growing season, says Keith O’Bryan agronomy research manager, Pioneer Hi-Bred. If you are unable to sample fields, you can also use yield maps and field histories to identify and treat potential hot spots.


Photo: John Deere 1790 CCS planter with Amvac's SmartBox system for nematicides and insecticides

Photo courtesy of Amvac Chemical Corporation