Carrot Root Knot Nematodes

Meloidogyne incognita, M. javanica, M. hapla, and M. arenaria

Root knot nematodes on carrot roots
Root knot nematodes on carrot roots [Credit: Scot Nelson]
Nodules on cantaloupe roots caused by Southern root knot nematode
Nodules on cantaloupe roots caused by Southern root knot nematode [Credit: Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org]
Root knot nematodes on a tomato plant
Root knot nematodes on a tomato plant [Credit: Scot Nelson]
Root knot nematodes on a tomato plant
Root knot nematodes on a tomato plant [Credit: Scot Nelson]


Host Plants:

On Crops: Carrots and many other vegetable crops. Over 90 species of nematodes are known to use carrots as a host crop.

Where Found:

Worldwide, wherever carrots are grown

Description:

Root knot nematodes are tiny 'eelworms' that live in soil and become plant parasites when they use carrot roots as their nurseries. Often nematodes enter carrots through the root tip, and this injury causes the root to fork, sometimes in several directions. As additional nematodes arrive to colonize the root, small feeder roots are destroyed, and irregular galls take their place.

Damage:

Carrot roots are twisted and deformed, with much forking and the presence of knobby galls on the outside of the roots. Above the ground, new growth slows as nematode pressure increases; infected plants pull easily from the ground.

Preventing Problems:

Carrots are more susceptible to root knot nematodes than any other garden crop. Nematodes are not very active in cool weather, so sometimes winter carrots will be successful even in soils where some nematodes are present. Good crop rotations prevent nematode buildup in many gardens, but root knot nematodes may be unavoidable in sandy soils in warm climates.

Managing Outbreaks:

Pull up affected carrots and dispose of them in the trash. Mark the area where the troubled carrots grew, and do not grow carrots there again.

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