Epidemiology of the Major Fungal Diseases of Cashew Tree (Anacardium occidentale L.) in Togo

Background and Objective: Cashew tree cultivation is currently booming in Togo and their nuts are Togo’s fourth most important agricultural export. A study was initiated to draw up an inventory of cashew fungal diseases and determine their epidemiological parameters. Materials and Methods: Thirty two cashew orchards were surveyed, with eight orchards per prefecture. Twenty trees per orchard were randomly selected along the diagonals and inspected. Incidence was defined as the proportion of cashew trees showing symptoms of a fungal disease. Severity was assessed on an arbitrary five-grade scale by assigning quality values to infected organs. The severity index was determined by a mathematical formula. Prevalence was the proportion of localities affected by a fungal disease per prefecture. Results: Eight fungal diseases were inventoried, including anthracnose, black rust, bud dieback, yellow leaf spot, pestalotiosis, powdery mildew, gummosis and ramularia. Incidence and severity index were 61.09 and 36.56%, respectively for pestalotiosis, 38.12 and 20.16% for leaf anthracnose, 35.62 and 14.84% for yellow leaf spot and 30.47 and 20.46% for bud dieback. The prevalence of anthracnose leaf spot was the most widespread (96.88%), followed by yellow leaf spot (84.38%), pestalotiosis (84.38%) and black rust (81.25%). Conclusion: Because of the impact of these fungal diseases, it would be necessary to use phytosanitary products, improve agricultural practices and introduce more resistant cashew cultivars for new cashew orchards.