Soil disinfestations, pathogen free plants. Cause - Meloidogyne spp. Symptoms - galls on roots of various size. Never on the woody roots so cannot confuse with crown gall. Imfected plants are stunted and wilt quickly in the heat.
Damage is usually in clusters of plants.
May be accompanied by severe root rot associated with decay of the galls. Often the root rot does most of the damage. Cycle - a bit complicated. Find it in the text. Use of marigolds has been touted in the popular media, but there is little evidence that it is better than crop rotation alone.