An Investigation on Coffee Thread Blight Caused by Corticium koleroga (Cke) Hoehnel and Its Associated Factors in Southwest Ethiopia

Thread blight caused by Corticium koleroga is a devastating disease that causes severe damage to C. arabica in south-western Ethiopia. However, it is one of the least researched diseases in Ethiopia. Therefore, the current work was designed with the objectives to assess the incidence and severity of the disease and identifying major factors associated with the disease intensity in south-western Ethiopia. For this purpose, field surveys were conducted on 180 farmers’ fields in 12 districts of major coffee growing areas in south-western Ethiopia during 2017 cropping season. The average thread blight incidence varied from 0% to 46% while mean disease severity ranged from 0% to 44%. The thread blight disease incidence and severity were higher at areas representing highland and midland altitudes compared with lowland altitudes. Thread blight severity was positively and strongly associated with rainfall (r=0.75) and relative humidity (r=0.85), but the disease severity was negatively and strongly associated with mean temperature (r=-0.79) and shade level (r=-0.50), while it was positively and intermediately correlated to altitude (r=0.44) and coffee production systems (r=0.36). The present study revealed the importance of coffee thread blight in south-western Ethiopia and identified factors associated with the disease intensity. Future research should be directed towards surveying more agro-ecologies to have a complete picture on the importance of thread blight disease across the country and to recommend disease management strategies.