Root knot nematode
Scientific name: Meloidogyne spp.
Synonym: Root knot eelworm
A wide variety of agricultural crops and weeds
Affected plant stages
All growth stages
Affected plant parts
Roots, leaves, the whole plant
Infected plants have swollen, impaired roots. Nematode's feeding stimulates the production of galls
(root knots). Galls are found on the root system both on the primary and secondary roots. Their sizes vary from .02 to 20 cm in diameter.
The gall is characterized by smaller swellings and more uniformly distributed infection on the lateral feeding roots. Inside the gall are shiny white bodies of the female nematodes
(about the size of a pinhead). At the root surface, shiny white to yellow egg masses are found. A closer look with a magnifier may show the adults, but mostly they are not seen with the naked eye.
Severe infestation results in stunted growth, yellowing of leaves, wilting, and poor yield because the galls disturb the roots ability to absorb water and nutrients. They also serve as openings for pathogens, such as fungi and bacteria, which cause plant diseases.
Factors that favor development
- Infected plant debris that are left on the field
- Weedy field
- Warm temperature and moist but well-aerated sandy soil
Prevention and control
- Crop rotation.
Broccoli, cauliflower, sorghum, Sudan grass, rape, and mustard seed are resistant to nematodes (Dofour; Guerena; Earles, 2003)
- Deep plowing
- Use of resistant cultivars
- Use of organic fertilizer particularly the chicken dung
- Grow healthy plants
- Regular and timely weeding
- Plant French marigold (Tagetes patula). Planting distance is 17.5 x 17.5 cm in between hills and rows. Two months after, plow them under (Vann; Kirkpatrick; Cartwright, 2004). African marigold (T. minuta) plowed under the soil also reduces nematodes on tomatoes (Dofour; Guerena; Earles, 2003)
- Basil extract
- Garlic extract
- Neem seed extract
- Pongam cake