Citrus root-knot nematode

Systematic position. Meloidogyne citri is a member of the phylum Nematoda, class Chromadorea, order Rhabditida, and the family Meloidogynidae. It is classified as an obligate endoparasitic nematode that specializes in attacking the root systems of specific woody perennials.

Host crops. The primary host range of this nematode consists of various citrus species. It is considered a significant pest in citrus-growing regions, where it impacts the vitality and commercial productivity of lemon, orange, and related citrus orchards.

Biology and life cycle. The life cycle comprises an egg stage, four larval stages, and an adult phase. Second-stage juveniles are the infectious form that migrates through the soil to locate a suitable root tip. Once they penetrate the roots, they become sedentary, induce the formation of giant cells, and form galls, where they feed and complete their reproductive development.

Damage and severity. The diagnostic sign of infestation is the development of distinct root galls, which significantly disrupt the plant's vascular tissue. This physical damage limits water and nutrient uptake, leading to chlorosis, stunted growth, a decline in fruit size, and, in severe cases, the gradual death of the root system.

Management strategies. Managing Meloidogyne citri is challenging due to its endoparasitic nature within the root tissue. Effective integrated pest management (IPM) practices include:

• Planting certified nematode-free nursery stock.
• Utilizing rootstocks with genetic resistance or tolerance to nematodes.
• Implementing pre-plant soil fumigation in heavily infested fields.
• Applying biological control agents such as predatory fungi or bacteria.
• Maintaining proper orchard hygiene to limit the spread of contaminated soil.