Gliricidia little leaf

The Gliricidia little leaf disease is a destructive condition affecting various leguminous trees, primarily Gliricidia sepium. The pathogen involved is a phytoplasma, a type of wall-less bacterium that resides within the plant's phloem tissue, effectively manipulating the host’s metabolic functions to facilitate its own survival and reproduction.

This disease is of particular concern for tropical agroforestry systems where Gliricidia serves as a multi-purpose tree for shade, green manure, and forage. Once infected, the plant's physiological capacity is crippled, leading to a significant reduction in biomass production, which directly impacts the sustainability of agricultural systems that rely on these trees.

The characteristic symptoms of the disease include dramatic leaf reduction, where leaves become stunted and deformed. Infected branches often show shortened internodes, creating a stunted, bushy appearance commonly described as a «witches' broom» growth pattern. Additionally, the tree's reproductive organs are frequently suppressed, preventing the development of flowers and seed pods.

The transmission of the disease is strictly dependent on insect vectors, mainly leafhoppers, which ingest the phytoplasma while feeding on the phloem sap of an infected plant. Once the insect becomes a carrier, it can transmit the pathogen to healthy trees during subsequent feeding events. Environmental conditions that support large populations of these vectors accelerate the spread of the infection.

Management of Gliricidia little leaf focuses on containment, as no curative treatment exists for phytoplasma-infected trees. Farmers are advised to immediately rogue and burn infected trees to stop the source of the pathogen. Preventative measures such as controlling vector populations with appropriate insecticides and ensuring the use of healthy, disease-free nursery stock remain the primary strategies for prevention.