Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu
Fall is the best time to soil sample for nematode pests such as root knot, lesion, and other plant parasitic nematodes. After fall harvest but before any fall tillage is done take soil cores six inches deep between plants in the row. Samples should be taken in the root zone of the old crop. Twenty cores/ sample should be taken from random spots in the field and placed in a plastic bucket gently mixed, and a pint of soil submitted for analysis. Large fields should be subdivided into blocks of 15- 20 acres each and sampled separately. Nematodes are not uniformly distributed in the soil and it would be easy to miss significant numbers if a single sample of 20 soil cores represented a large acreage. Nematode test bags and instructions are available for purchase from the county Extension offices. Samples cost $10.00. Fall sampling for root knot nematodes is strongly recommended for fields that will be planted in cucumbers, watermelons, cantaloupes, lima beans or other high value vegetables where root knot could reduce production. Forms and instructions are also available on the web at http://ag.udel.edu/extension/pdc/index.htm.