Trichoderma Species Against Gummosis Disease in Lemon Trees

Abstract

Phytophthora citrophthora (Smith and Smith) Leon. causes gummosis, foot and collar rot of trees, and brown rot of fruits in citrus areas in Turkey. Gummosis is very frequent especially in all citrus growing areas, and is the most important disease of lemon besides mal secco. Gummosis mainly affects the bark of trunks, and the main symptom is the formation of dark colored gum on the surface of the bark and cambium. The decayed bark shrinks, cracks and shreds as it dries out, and gum exudes from the cracks. Callus tissues are often developed in the bark to restrict further spread. The extent of lesions depends on the citrus species and on climatic conditions. In extreme cases, the tree is killed. The causal agent also infects fruit, resulting in a firm, light brown decay. Fruits near the ground become infected when splashed with the soil containing zoospores of the fungus. The pathogen attacks the plants under special cultural conditions, particularly during frequent heavy irrigations or prolonged periods of rainy weather.