Pruning quality affects infection of Acacia mangium and A. crassicarpa by Ceratocystis acaciivora and Lasiodiplodia theobromae

Abstract

Pruning (singling) is a common silvicultural practice in commercial Acacia plantations because these trees tend to have multiple stems. The wounds resulting from pruning are susceptible to infection by pathogens. Ceratocystis acaciivora and Lasiodiplodia theobromae have been shown recently to be important pathogens of A. mangium in Indonesia, where they are commonly associated with wounds on trees. The aim of this study was to determine the impact of different wound types on infection of A. mangium and A. crassicarpa by these two pathogens. Isolates of C. acaciivora and L. theobromae, found to be the most pathogenic in a prior study, were used to inoculate pruning wounds. Results showed that pruning conducted in a manner to reduce stem damage, resulted in lower levels of fungal infection. Where pruning resulted in tearing of the bark, there were higher levels of infection and disease occurred even without artificial inoculation. Inoculation of pruning wounds with C. acaciivora and L. theobromae showed that both fungi have the potential to cause disease. However, C. acaciivora was most virulent. Results of this study showed conclusively that careful pruning will result in lower levels of disease in young A. mangium and A. crassicarpa plantations.