Nematode, Root-knot

Plants infested with root-knot nematodes appear unthrifty and off-color, growing slowly despite adequate water and nutrients. Careful excavation reveals the telltale sign: enlarged galls or knots on roots of all sizes, often with a tangle of fibrous rootlets sprouting around them. In sandy soils, the stunting is severe. Yield and plant longevity decline noticeably, and affected plants weaken, making them vulnerable to other pests and diseases.

These nematodes live permanently in soil, so you must disrupt their life cycle rather than eliminate them outright. Fallow periods and cover crops are your primary tools; avoid planting susceptible crops in the same spot for several years. Yellow mustard and some Brassica species contain compounds active against nematodes, making them excellent rotation crops. Maintain meticulous weed control during fallows, as many weeds host root-knot nematodes. Soil sampling in fall before planting the following spring gives you time to implement management before new crops go in.