Ceratocystis fimbriata infecting Eucalyptus grandis in Uruguay

Uruguay has a rapidly growing forestry industry consisting mainly of exotic Pinus and Eucalyptus spp. Recently, there have been reports of individual E. grandis trees wilting and dying rapidly in plantations. The aim of this investigation was to survey the dying E. grandis in the Rivera area of Uruguay and to determine the cause of the Eucalyptus wilt. Sap-staining symptoms were observed on recently pruned E. grandis. Discs of discoloured wood were cut from these pruned trees and from the stems of dying trees. These disks were stored in a moist environment to induce fungal sporulation. Ascomata, typical of a Ceratocystis sp., were found covering the edges of the wood where streaking symptoms occurred. Morphologically, the fungus resembles C. fimbriata. The internal transcribed spacer regions of the ribosomal RNA operon of the Ceratocystis sp. were amplified and sequenced. Sequence data confirmed placement of this fungus amongst other isolates of C. fimbriata. Furthermore, the sequence data showed that the Uruguay isolates are most closely related to those from diseased Eucalyptus spp. in Brazil, Congo and Uganda. C. fimbriata is a well-known pathogen of many woody plants and could constitute a serious threat to intensively managed E. grandis in Uruguay where the fungus was not previously known. The relationship between the pruning of E. grandis and infection by C. fimbriata will, in future, need to be evaluated.