Coffee root-knot nematode

Systematic position. Meloidogyne exigua belongs to the phylum Nematoda, class Chromadorea, order Rhabditida, and family Meloidogynidae. It is a sedentary endoparasitic nematode that is recognized globally as one of the most critical threats to sustainable coffee production in tropical regions.

Host crops. The primary host of Meloidogyne exigua is the coffee plant (Coffea arabica). While coffee is its main economic target, the nematode is polyphagous and can infest various other plants, including citrus, tomatoes, and multiple weed species, which can act as reservoirs in infested fields.

Biology and life cycle. The nematode completes its life cycle within the root tissues of host plants. The second-stage juveniles (J2) penetrate the roots and migrate to the vascular cylinder. Feeding activities induce the formation of giant cells, leading to the development of characteristic galls on the roots. Females become sedentary, inflating into a pear-like shape and laying eggs into a gelatinous matrix.

Damage and severity. Infested plants exhibit poor vigor, reduced leaf size, and chlorosis. The galls on the roots impair the uptake of water and nutrients, leading to stunted growth and significant yield losses. In severe cases of infestation, the root system decays, which can lead to the death of the plant and necessitates the clearing of entire production areas.

Management and control. Controlling Meloidogyne exigua requires an integrated pest management (IPM) strategy:

• Use of nematode-free, certified nursery seedlings.
• Selection of resistant or tolerant coffee cultivars as a long-term solution.
• Soil solarization and the use of organic amendments to improve soil health.
• Implementation of biological control agents, such as specific bacteria or fungi, that suppress nematode populations in the rhizosphere.