Field Diagnosis and Management of Phytophthora Diseases

Phytophthora species are important soil-borne fungal pathogens worldwide that attack the root systems, trunks, and fruit of citrus trees at any age. Historical reports from Florida indicated Phytophthora was a problem as early as 1876 on sweet orange seedlings. When roots or tree trunks are affected, the foliage turns yellow and exhibits poor growth, leaves drop, twigs die back, and fruit size and yield are reduced. As fungal infection of roots and bark progress, the above-ground symptoms increase in severity. Ultimately, trees may decline and die.