Okra Root Knot Nematodes

Meloidogyne incognita in warm climates, M. hapla where winters are cold
Also known as Okra

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


Host Plants:

On Crops: Okra and many other vegetable crops. Okra is highly susceptible to root knot nematodes

Where Found:

Worldwide, wherever okra is grown

Description:

Root knot nematodes are tiny 'eelworms' that live in soil and become plant parasites when they use okra roots as their nurseries. Often nematodes enter okra roots through small injuries. As their numbers multiply, small feeder roots are destroyed, and irregular galls take their place.

Damage:

Plants grow slowly, in erratic spurts, and are generally dwarfed in size. When you dig up a troubled okra plant, numerous swellings and galls are evident on the roots. Because root knot nematodes don’t move far in the soil without human help, neighboring plants may be infected while those at the end of the row remain healthy.

Preventing Problems:

Okra is highly susceptible to root knot nematodes, in part because it thrives in the same hot summer conditions that please nematodes. Good crop rotations prevent nematode buildup in many gardens, but root knot nematodes may be unavoidable in sandy soils in warm climates. To increase your chances of success, grow a summer crop of French marigolds, followed by a winter cover crop of oats, wheat or rye. Then try okra. Regularly amend soil with materials that contain chitin, such as seafood meal, eggshells, or shrimp hulls. In the soil, these materials feed microorganisms that chow down on chitin, including nematode eggs.

Managing Outbreaks:

Pull up badly affected okra plants, lop off the roots, and dispose of the roots in the trash. Compost the rest. Mark the area where the troubled okra grew, and do not grow okra or carrots there again. If plants are only slightly affected, they may make a crop if a deep mulch is used to keep the root zone cool and moist.

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