Calonectria variabilis causando mancha foliar e desfolha em plantios clonais de Eucalipto no Agreste da Bahia

Abstract

The genus Calonectria includes a group of phytopathogenic fungi widely distributed in the world, with a high impact on agricultural and forestry crops. In Brazil, 37 species were identified affecting commercial plantations, especially Eucalyptus spp., causing leaf spot and defoliation, which when severe affect growth and productivity. Among the Calonectria species, C. variabilis is reported as an important pathogen in tropical and subtropical regions. The aim of this study was to identify fungal isolates obtained from commercial plantations of Eucalyptus sp. in Agreste of Bahia, Brazil, using morphological and phylogenetic analyses, as well as assessing the pathogenicity of these isolates. For this purpose, leaves with typical symptoms of the disease were collected to obtain the isolates, which were characterized based on the sequences of the cmdA, his3, tef1 and tub2 genes, as well as the observation of morphological structures. Based on these analyses, was confirmed that the isolates belong to the species C. variabilis, grouping together in a clade with other isolates of the species, supported by high bootstrap values and posterior probability in the phylogenetic analyses. The pathogenicity tests confirmed that the fungus is responsible for inducing necrotic symptoms on eucalyptus leaves, indicating its phytopathogenic potential. The results obtained increase knowledge about the distribution and diversity of Calonectria spp. in Brazil and provide essential information for monitoring and control of the disease in commercial eucalyptus plantations.