Citrus diseases caused by Phytophthora species

Different species of Phytophthora cause serious and economically important soilborne diseases of citrus throughout the World. Tree and crop production losses occur from damping-off of seedlings in the seedbed, root and crown rot in nurseries, foot rot and fibrous root rot, and brown rot of fruit in groves. Foot rot results from infection of the bark near the ground level producing lesions on the trunk or crown roots that can girdle and kill the tree. Phytophthora spp. also attack and cause the decay of fibrous roots especially on susceptible rootstocks in nurseries. In bearing groves, fibrous root rot damage causes tree decline and yield losses. Phytophthora spp. infect fruit causing brown rot that leads to fruit drop in the groves and postharvest decay. The most important species include P. parasitica, P. citrophthora and P. palmivora. Management of Phytophthora-induced diseases, involves integration of cultural practices (e.g., disease exclusion through use of Phytophthora-free planting stock, resistant rootstocks, proper irrigation practices etc.) and chemical control methods.