Eucalyptus die-back in South Africa associated with Colletotrichum gloeosporioides

Abstract

Die-back of members of several Eucalyptus species, clones and hybrids was observed during a survey of forest plantations in the Mpumalanga and KwaZulu-Natal provinces, South Africa. This symptom was often associated with agents of environmental stress such as drought, frost and hot winds. Botryosphaeria dothidea , a well-known pathogen of Eucalyptus was frequently isolated from twigs showing die-back symptoms. In some cases, Colletotrichum gloeosporioides was isolated together with B. dothidea. Artificial inoculations of members of a Eucalyptus grandis clone with both fungi resulted in lesion development. Although C . gloeosporioides was isolated much less frequently and only in the Mpumalanga Province, it gave rise to larger lesions after inoculation than did B . dothidea . This is the first report of die-back of Eucalyptus trees caused by C . gloeosporioides in South Africa.