Root-knot nematode

Meloidogyne spp.

also called root knot eelworm

Rounded galls and swellings all along the roots, with plants above wilting and starving despite watering; lift a sufferer and the knotted roots give it away.

Nematode Serious Soil-borneSpread in waterSpread on tools & hands Spreads to neighbors

What you'll see

Roots carry rounded galls and knotty swellings, unlike the firm nodules of legumes.
Plants wilt in warm weather and recover poorly even when watered.
Growth is stunted, pale, and lacking vigor.
Yields fall and plants may die back in patches.
Fine feeder roots are distorted and reduced.

Why it happens

Root-knot nematodes are microscopic soil-dwelling roundworms of the genus Meloidogyne. Their larvae invade the roots and cause the plant to form galls around them, choking the flow of water and nutrients. They arrive on infested soil, water, tools, or bought-in plants.

They thrive in warm, light, sandy soils and are most damaging under glass and in hot summers, building up where the same susceptible crop is grown repeatedly.

Treating it

There is no chemical cure for the gardener; lift and destroy badly affected plants.
Rest the ground from susceptible crops so numbers fall for want of a host.
Grow affected crops in fresh sterile compost in pots or bags meanwhile.
Keep plants well watered and fed to help them tolerate light infestations.

Keeping it away

Rotate crops widely and avoid growing the same host on infested ground.
Buy in clean plants and use fresh compost under glass.
Grow a French marigold or mustard green-manure break, which can suppress numbers.
Clean soil off tools, boots, and pots to avoid carrying it to fresh ground.

Who gets it

Tomato, cucumber, lettuce, carrot, potato, and many vegetables and ornamentals, especially under glass.