Root-knot nematode damage to celery roots

Root-knot nematodes (Meloidogyne spp.) are plant-parasitic nematodes from the genus Meloidogyne. They exist in soil in areas with hot climates or short winters. About 2000 plants are susceptible to infection by root-knot nematodes and they cause approximately 5% of global crop loss[1] Root-knot nematode larvae infect plant roots, causing the development of root-knot galls that drain the plant's photosynthate and nutrients. Infection of young plants may be lethal, while infection of mature plants causes decreased yield.


Main symptoms are found on the roots of the plant as a swelling of the roots from within resulting in galls. The size of galls varies depending on species and should not be confused with leguminous root nodules.[2] Root nodules are attached to the root and can be removed easily, root-knot galls cannot.

Above-ground symptoms include; stunting, poor growth, yellowing, chlorosis, wilting, yield reduction and premature death. Heavily infected plants do not respond to watering or fertilisation due to nematode infection of roots.[2]



Some of the nematicides that can be used to kill root-knot nematodes and other nematodes in the soil are:[2]

  • Dazomet (Basamid), a granular formulation that can be used for seedbed treatment. When incorporated in moist soil dazomet releases methyl isocyanate gas, which kills nematodes.
  • Fenamiphos (Nemacur), another granular formulation that can be used before or at planting or in established crops.
  • Oxamyl (Vydate) in a liquid formulation, which is supplied with an application gun that makes application into the soil safer.


Rotivation of the soil between crops will expose nematodes to heat and sunlight killing them.[2]

Crop Rotation[]

Practice crop rotation; avoiding planting any of the following potential hosts sequentially (especially following confirmation of an infection):



  1. Sasser, .J.N. Carter, .C.C. (1985). Overview of the International Meloidogyne Project 1975–1984. In An Advanced Treatise on Meloidogyne. Edited by: Sasser, .J.N. Carter, C.C. Raleigh: North Carolina State University Graphics. p19-24.
  2. a b c d Kirby, M.F. Revised by Gowen, S.R. Ruabete, T.K. Wright, J.G. (2005). Root-knot nematodes. Secretariat of the Pacific Community. ISSN 1017-6276. 3rd Edition.
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