Characterization of ceratocystis wilt on eucalyptus and its causal in Southern Bahia, Brazil

Abstract

Fungi of the Ceratocystis fimbriata complex are important pathogens in woody species, being associated with symptoms of wilt, trunk lesions and death of infected plants. In eucalyptus plantations, these pathogens can reduce the productivity of affected plants, in addition to causing high mortality in the first years of planting. The objective of this work was to evaluate the symptoms and characterize isolates of Ceratocystis associated with eucalyptus plantations in southern Bahia, Brazil. In this study we observed that external symptoms manifested mainly in trees with up to 36 months of planting, however asymptomatic diseased trees were found until the end of the cycle (7 years). Symptoms of wilt, wood discoloration, formation of adventitious shoots and bark lesions, drying of branches and death have been observed in diseased trees. The discoloration of the wood began in the root system, which is probably the point of penetration of the causal agent. The isolates obtained from these trees were identified as belonging to the species Ceratocystis manginecans, presenting optimum growth temperatures ranging from 23.9 to 24.9oC. Eucalyptus clones inoculated with these pathogens showed different levels of resistance. Clones resistant to a certain isolate may be susceptible when infected by another. This variation in aggressiveness among Ceratocystis isolates makes the selection of resistant clones difficult. The present work improves the understanding of ceratocystis wilt in eucalyptus and its causal agent.