African root-knot nematode

Systematic position. The African root-knot nematode (Meloidogyne acronea) belongs to the phylum Nematoda, class Chromadorea, order Tylenchida, and family Meloidogynidae. This species is a highly specialized plant-parasitic nematode known for infecting the root systems of various crops and causing physiological disorders that impede normal plant development.

Host plants. The primary host of this nematode is cotton (Gossypium spp.). However, the pest is capable of colonizing a range of weed species and certain legume plants, which serve as alternate hosts, allowing the nematode population to survive in the soil even when the primary crop is absent from the field for one season.

Biology and lifecycle. The lifecycle consists of eggs, four larval stages, and adults. Infective second-stage juveniles emerge from eggs and penetrate root tissues. Once inside, they become sedentary, feed on root cells, and induce the formation of specialized feeding sites. The developmental rate is significantly influenced by soil temperature and moisture levels, which determine the number of annual generations.

Damage and pathogenicity. Infestations result in stunted plant growth, chlorosis, and poor foliage development. The destruction of root tissue disrupts the uptake of water and nutrients. Furthermore, the root lesions act as entry points for secondary fungal and bacterial soil-borne pathogens, leading to root rot and significant yield losses in cotton production.

Control measures. Integrated pest management (IPM) is essential for controlling Meloidogyne acronea. Key strategies include:

• Crop rotation with non-host crops to starve the nematode population.
• Use of resistant cotton cultivars.
• Deep plowing to expose nematodes to adverse conditions.
• Application of chemical nematicides when necessary.
• Strict weed control to eliminate alternative hosts.