Symptoms of this disease are similar to those of clubroot, but clubroot-affected plants produce larger, more continuous swellings on the older portion of their roots. Root-knot nematodes on crucifers induce prolific root branching and galling above the point of infection. Invasion of infected roots by fungi may occur. Aboveground symptoms include stunting, chlorosis and wilting. Though infected plants may survive a growing season, the resulting crop is generally small and may be unmarketable.
Conditions for Disease Development
These nematodes survive in infected root debris. Juveniles are attracted to root exudates of host plants and feed on root tissue. The most severe damage can occur in sandy soil with moderate moisture, but these nematodes are not limited to these conditions. Infection can occur at temperatures ranging from 10-35°C (50-95°F). Freezing temperatures kill all lifecycle stages of Meloidogyne species.
Soil fumigation, flooding or fallow farming help control populations of root knot nematodes.