Pathogenicity and susceptibility/resistance reaction of feijoa (Feijoa sellowiana) cultivars to anthracnose

Abstract

The objective of this study was to determine the pathogenicity of Colletotrichum theobromicola, C. siamense and C. fructicola, C. nympahaeae and C. pseudoacutatum to feijoa, as well as to study the susceptibility/resistance reaction of the commercial cultivars "Alcântara", "Helena", "Mattos", and "Nonante" to anthracnose. For that, spore suspensions (106 spores mL-1) of the Colletotrichum isolates were prepared from colonies grown for seven days in Mathur medium. Ten fruits at the medium stage of development of each cultivar were used for the inoculation of each isolate. First the fruits were disinfested superficially, then they were accommodated in polypropylene trays and the suspension was applied in three places on the fruit's surface, without injury. All those species are pathogenic to feijoa, as they reproduced the original symptoms of anthracnose. The susceptibility of cvs. "Helena" and "Nonante" were influenced by the specific variability of the pathogen. The cv. "Alcântara" is susceptible and cv. "Mattos" is resistant to all tested Colletotrichum species. Thus, cv. "Mattos" is the most suitable feijoa cultivar to reduce anthracnose levels in orchards in a conventional, integrated or organic cultivation system.