If several genera or species are in a field, it is difficult to find a rotational crop that will not favor the buildup of at least one kind of nematode. Do not plant fall beans behind a root-knot susceptible crop, such as cucumbers, tobacco, cotton, squash, tomatoes, cantaloupes, peas or beans. Leaving the land fallow during the summer or planting rye in the field in the fall should reduce the root-knot nematode population. The application of a fumigant type nematicide in the row before planting is the best way to control nematodes in beans. Fumigants can be applied by a gravity-flow applicator, and should be placed 6 to 8 inches deep in the row.
Fumigants require a two-week waiting period between application and planting.
The non-fumigant Mocap may be used at seeding. Mocap should not be used under heavy root-knot pressure situations. Rust Rust, caused by the fungus Uromyces phaseoli var. The rust fungus is not seed-borne, but overwinters on old bean plants. Spores produced on old bean plants are spread to new bean foliage by the wind.