Distribution and management of Phaeoramularia leaf and fruit spot disease of citrus in Ethiopia

Abstract

Introduction. Citrus is the most important fruit crop widely grown by small-scale and commercial farms in Ethiopia. However, productivity of citrus in many parts of the country is threatened by Phaeoramularia leaf and fruit spot disease caused by Phaeoramularia angolensis. Surveys and field experiments were conducted to map the geographical distribution, and to study the efficacy of different fungicides for the control of this disease. Materials and methods. Surveys were conducted in the major citrus-growing areas (south, south-west and north-west) of Ethiopia. Random sampling techniques were used for sample collection. The efficacy of different fungicides against P. angolensis was studied under a hot-spot area, based on disease incidence and severity, and marketable fruit yield. Results and discussion. Phaeoramularia leaf and fruit spot disease of citrus has been widespread throughout the south, south-west, and north-west of Ethiopia, causing complete crop failure. This disease was more severe in smallholder farmers' fields as compared with the commercial orchards. The severity of P. angolensis was varied between different citrus species and areas with different agro-ecologies. The south and south-west part of the country, characterized by high and frequent rainfall with high humidity, were severely affected by the disease. Field application of Benlate, Score and Cuproxat significantly reduced the incidence and severity of the disease and, thereby, increased marketable fruit yield. Conclusion. Phaeoramularia leaf and fruit spot disease of citrus has become widespread in many parts of Ethiopia within a short period. Further investigation on P. angolensis biology and detailed epidemiological studies are mandatory to develop a model, and, thereby, to facilitate forecasting systems for effective and sustainable management of leaf and fruit spot disease of citrus in Ethiopia.