Assessment of <i>Eucalyptus</i> Canker Diseases in Plantations of Uganda

ABSTRACT Eucalyptus is one of the most widely grown industrial crops worldwide. This wide distribution comes with many diseases due to the wide exchange of germplasm, and Eucalyptus being a suitable host for indigenous pathogens. Eucalyptus plantations in Uganda are affected by stem canker diseases that have reduced productivity. Therefore, it is crucial to understand the prevalence and distribution of canker diseases among species and clones and regions in order to develop management strategies. A nationwide survey on Eucalyptus canker diseases was conducted in different regions, hereafter clusters, of Uganda. The most prevalent disease in all clusters was Botryosphaeria canker, mainly affecting Eucalyptus grandis , E. camaldulensis and the GU hybrid clone ( E. grandis × E. urophylla ). However, the most severe disease was Teratosphaeria canker, which affected 50% of the GC hybrid clone ( E. grandis × E. camaldulensis ). The incidence and severity were highest in the Western and Central Uganda clusters, respectively. The incidence and severity varied significantly with age, with 41% of trees less than 5 years in age being the most affected. Plantations with mixed species, mixed hybrid clones and mixed species with hybrids had the lowest disease incidence and severity compared to monocultures. The findings indicated that, although Botryosphaeria canker was the most prevalent of these diseases, Teratosphaeria canker caused more damage to Eucalyptus plantations in Uganda, with the highest severity recorded in monocultures and clusters characterised by high annual rainfall (1244–1356 mm per year). This information will help Eucalyptus growers carry out site‐species matching and select appropriate combinations of species and clones for canker disease management and better yields.