Harvest is moving along, and now is the time to consider pulling nematode samples if you suspect the problem to assess populations. As long as cotton is alive, it can be a food source to continue to build populations that would be battled next year.
While the food source is still available , and temperatures are still warm enough, it is important to sample to see what species and how much of a population is in the field. This may influence what crop you want to plant or if a nematicide is justified.
Now that we have caught some rain in the county, soil conditions should be optimum for pulling the sample. It is important to sample near the root zone of the cotton stalk, and about the same depth of a regular soil sample around the root zone for accurate results.
It is also important to keep the samples cool and not exposed to extreme condition such as sun and heat because it can kill the nematodes and interfere with accurate results.
Posted below are some good publications on sampling, timing, nematode species, crop hosts, etc, for your reference.