Phosphite: Roles in phytophthora tree diseases management

Abstract Tree pathogens like Phytophthora spp. cause significant economic damage. Resistance inducers (RIs) are used to manage some forest pathogens. RIs are known to elicit the innate defense capacity of trees against diseases. The exogenous application of compounds like phosphite can trigger induced resistance (IR). Phosphite, an inorganic salt of phosphorous acid, is a well-known RI. Some of the resistance processes are the production of antimicrobial substances, leaf lignification, increased cell wall thickness, and the synthesis of plant metabolites. Phosphite treatment assists trees to recuperate from the damage or may stop further disease advancement. Factors like application method and timing, pathogen susceptibility, the amount of phosphite in the soil, and the amount absorbed by the plant determine the performance of phosphite in tree disease management. One of the drawbacks of phosphite is its phytotoxicity. However, phytotoxicity can be minimized by scrutinizing the appropriate methods of application and dosage. In this review, the use of phosphite in the management of tree-damaging Phytophthora diseases in trees is briefly covered. Besides, phosphite application methods, phosphite toxicity to trees, the synergies between phosphite and other compounds, MRL, and phosphite residue in trees are reviewed.