Diseases of plantation Eucalyptus in Uganda

A survey of diseases of plantation Eucalyptus was conducted in southern Uga nda during June 1999. The aim was to compile a preliminary list of pathogen s in planning future plantations and breeding programmes. Root, stem and le af samples were collected from trees ranging in age from a few months to ap proximately 10 years. The most commonly isolated pathogen was Lasiodiplodia theobromae, which was frequently associated with stem cankers and die-back . Bacterial wilt, caused by Ralstonia solanacerarum, was the most common ca use of death of trees less than two years old, in the warmer areas around K ampala. In the eastern part of Uganda, the wilt pathogen Ceratocystis fimbr iata was isolated from dying E. grandis and, together with L. theobromae, i s considered the greatest threat to plantation Eucalyptus in Uganda. Other, less important, pathogens isolated during the survey included a species of Mycosphaerella from leaf spots and a Valsa species associated with stem ca nkers.