ABSTRACT
Not much work has been done on induced resistance of Citrus to pathogens. Studies with Phytophthora citrophthora (Smith and Smith) Leonian indicated that morphological exclusion of the fungus in mature cells cannot be responsible for Citrus resistance to this pathogen, and biochemical or physiological factors may also be involved in resistant and susceptible reactions. Mature cells of resistant Citrus species may possess inhibitors, or hypersensitivity reaction may be induced by substances produced by the plant cells after infection (Broadbent, 1969).
