Root-knot nematode

Causal agent and disease type: The root-knot nematode (Meloidogyne incognita) is a microscopic soil-borne endoparasite that causes significant plant diseases known as meloidogynosis. By invading the roots of host plants, these nematodes establish feeding sites that disrupt the plant's vascular system, preventing the efficient uptake of nutrients and moisture, which leads to general growth stunting and decline.

Affected crops: This pest is a polyphagous organism with a massive host range, capable of infecting over 2,000 plant species. Among the common crops vulnerable to its attack are onion, garlic, celery, peanut, oats, fodder beet, Indian mustard, and winter oilseed rape. The ability to survive on a wide variety of commercial and weed species makes it a persistent challenge in integrated pest management.

Symptoms and signs: The characteristic diagnostic feature is the formation of root galls, which are knot-like swellings on the root system where female nematodes develop and reproduce. Above-ground symptoms include yellowing of foliage, poor development, wilting during peak sunlight hours, and premature death. Infected roots often become distorted and may show secondary rot due to opportunistic bacterial or fungal infections.

Conditions for development: Meloidogyne incognita thrives in warm, moist, and well-aerated soils. Temperatures between 25°C and 30°C are ideal for rapid lifecycle completion. The pest is easily disseminated through infested soil moved by farm machinery, contaminated irrigation water, and the transfer of infected seedlings or plant parts, allowing it to colonize new fields rapidly.

Protection and prevention measures: Controlling the root-knot nematode requires an integrated strategy to minimize soil populations:

• Use certified nematode-free seeds and transplants for planting.
• Implement crop rotation cycles utilizing non-host or trap crops to break the life cycle.
• Maintain soil hygiene by cleaning equipment after contact with infested areas.
• Apply chemical or biological nematicides where soil infestation levels exceed economic thresholds.
• Improve soil health through the use of organic amendments and antagonistic green manure crops.