“This is the basic information needed to manage nematode populations adequately,” Ye said. “With these details, growers can make informed decisions about which crops to plant and whether or not to use chemical treatments.”

Growers are advised not to grow the same crop in the same field year after year. Many nematode populations can be kept at manageable levels by choosing good rotation crops.

It is also not advisable to use the same nematicide on the same field year after year, said Ye. Routine application is expensive, may be unnecessary and can lead to the build-up of nematicide resistance.

Instructions for collecting and submitting samples for nematode assay are available online at www.ncagr.gov/agronomi/pdffiles/samnemas.pdf. Samples can be taken now or immediately after crop harvest in the fall — when nematode populations are likely to be at their highest. However, the process for collecting samples now, while a crop is in the field, is different from that recommended after harvest when damage cannot be seen.

Samples collected from an existing crop are problem, or diagnostic, samples and should be collected from the edge of the affected area. For comparison, each problem sample should be submitted along with a sample from a “good,” or relatively healthy looking, area in the same field. On the other hand, samples collected after harvest are routine, or predictive, samples and should randomly represent the entire field.

For further advice on how to collect samples or manage nematode populations, contact your NCDA&CS regional agronomist by visiting www.ncagr.gov/agronomi/rahome.htm or calling (919) 733-2655. Schedule a site visit if you need help troubleshooting nutrient or nematode-related crop growth problems.