Infected plants do not produce flowers. Shoots are weak. Small knobby swellings appear on the small roots, and soft yellow areas appear on the large roots. QDig up and burn infected plants. Root Knot Root knot, or root gall, is caused by nematodes.
Nematodes are tiny worms that feed on many kinds of plants.
They are most damaging where winters are mild, where the growing season is warm, and where the soil is light. Nematode-infected plants lack vigor. They produce only a few small flowers. Stems are short and thin. Leaves are light green.