Nearly all kinds of plants in northern greenhouses and outdoors in southern states are attacked by root knot. Plants are stunted, often wilt, yellow, and die. Round nodules or long, irregular, highly branched swellings on roots are caused by nematodes and block the flow of water and nutrients. To control root knot, plant nematode-free plants using a four-year rotation. Use sterilized soil in greenhouses. Plant resistant varieties.
