- In the past, soil-directed organophosphate and carbamate insecticides gave some secondary suppression of nematodes. Currently, more selective insecticides, and Bt corn for corn rootworm control, don’t provide secondary suppression of nematodes.
- The increase of no-till production can favor certain nematodes that are sensitive to tillage (needle and dagger nematodes).
- More corn-following-corn also favors the needle and dagger nematodes.
For sampling in the autumn, use a soil probe and sample within the row—that’s right, within the row. This is different from sampling for soil fertility. Sampling within the row allows you to get a count of destructive endoparasitic nematodes (lesion and lance nematodes), because many of those adults leave the root as the crop dries down and the roots die. Sample when the soil is moist but not wet. Walk a zig-zag pattern, and take 20 cores to a depth of 12 inches. Gently mix these cores in a container. Don’t let them dry out nor be subject to temperature extremes before mailing as soon as feasible to a nematode laboratory.
Laboratories that can analyze nematodes in soil samples collected at this time of year include:
- Purdue University, http://extension.entm.purdue.edu/nematology/cv/submissionform.pdf
- Mississippi State University, http://msucares.com/pubs/misc/m1230.pdf
- University of Florida, http://edis.ifas.ufl.edu/sr011
- Iowa State University, http://www.extension.iastate.edu/Publications/PD32.pdf