Characterization of fusarium spp., a phytopathogen of avocado (persea americana miller var. drymifolia (schltdl. and cham.)) in Michoacán, México

Avocado has great socioeconomic importance in Mexico because of the benefits it generates for the production chain participants and the significant foreign exchange earnings engendered by the export of its fruit. However, this crop has phytosanitary problems, caused mainly by fungi, among which the genus Fusarium stands out. The objective of this study was to characterize Fusarium species that caused root rot in avocado trees in Michoacan, Mexico. In 19 isolates of Fusarium spp., polymerase chain reactions (PCR) with primers coding for elongation factor and calmodulin genes were performed. These sequences were compared in homology using BLAST analysis and aligned in MEGA 6.0. Cladograms were created based on maximum verisimilitude. The pathogenicity of the isolates was evaluated based on their virulence and severity in the avocado plants. Morphological and molecular analyses showed that 15 isolates belonged to F. oxysporum Schl and four to F. solani Mart. All isolates were pathogenic, with virulence ranging from 16 to 56 days. All isolates produced root rot and yellowing of leaves, with 63% producing wilting and 16% producing apical necrosis, the latter being the most severe.