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Free corn nematode assays being offered in 2019
Author: Travis Faske, Extension Plant Pathologist

By Travis Faske, Extension Plant Pathologist/Peanut Specialist

Yes, that’s right, free corn nematode soil assays. Thanks to the Arkansas Corn and Grain Sorghum Board for sponsoring and the Arkansas Nematode Diagnostic Lab (ANDL) for processing, farmers and consultants will be able to cash in on fee corn nematode assays for the 2019 cropping season.  Currently, we know that southern root-knot nematode, lesion nematode, and stubby root nematode are often found in corn nematode samples, but it is unknown which is the most common in our state. Some corn nematodes cause stunting (Fig. 1.), while others are more subtle, robbing corn of water and nutrients, so be in the know by collecting a soil sample this spring.

An online course is available on “collecting and packaging nematode soil samples” that will provide information on how to collect soil samples for nematode assays and how to submit samples online through the DDDI system.  A summary for sampling corn fields for nematodes is outlined below along with link to “general guidelines” provided by the Nematode Diagnostic Lab.

Figure 1. Stunted corn caused by a severe population density of corn nematodes in Arkansas.

Sampling: General Guidelines

  • Timing:  Corn growth stages are between V2 and V6.  
  • Field:  Divide field into 20 acre blocks/quadrant or by natural borders or soil types to gain a better understanding of nematode diversity within the field.  
  • Root Zone:  Using a ¾ inch soil sampling tube (similar to that for soil fertility) sample 2 to 3-in from corn plants at 8-10 inches deep into and below the root zone. 
  • Patterns:  Collect 1 to 20 soil cores in a zig-zag pattern within each block. Other sampling patterns like “W” or “M” patterns are also common.  
    • Note:  Previous crop, soil type, and history of corn production are some of the information requested on the DDDI forms.
  • Sample Volume:  Mix soil in bucket and collect a 1-pt. subsample for processing.  Place in plastic bag, tie or seal shut, and label (on bag or tag used to tie bag closed) as to cross reference back to sampled field. 
  • Sample Care:  Place samples in a cool place during collecting and transport.  Use an ice chest (NO ice) to avoid extreme shift in temperatures.  Place cooler in shade and away from direct sunlight when sampling on hot, sunny days. Direct light on a plastic bag is like a greenhouse and can warm and kill nematodes in a sample.  At the end of the day, spread out bags in a cool place (office floor, or another a/c room).  Ship as soon as possible as to avoid storage over the weekend by shipping company.  Local county Extension offices can assist with shipping.

There is no limit on the number of free samples that any county or individual can submit; however, the timing for corn sampling is here, so take advantage of it. Samples will be accepted from farmers, consultants, or county agents.

For other questions please contact the Arkansas Nematode Diagnostic Labor myself at

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