The occurrence of Alternaria species on cabbage in Iran

Abstract

In a study on Alternaria species, associated with cabbage black spot disease in Urmia, West Azerbaijan, Iran, cabbage fields were inspected during the growing seasons of 2012–2013 and leaves with suspected symptoms of Alternaria infection were collected. A total of 135 isolates with Alternaria characteristics were obtained from 10 main growing areas in this region and studied taxonomically. On the basis of morphological characteristics of the studied isolates, 8 species viz. Alternaria arbusti, A. brassicicola, A. destruens, A. infectoria, A. perangusta, A. tenuissima, A. turkisafria and A. vaccinii were identified. Alternaria tenuissima with 53 isolates, A. brassicicola with 38 isolates and A. destruens with 29 isolates had respectively the highest frequency among the identified species and distributed all over the studied area. A. arbusti and A. perangusta each with only one isolate had the lowest frequency. Results obtained from the pathogenicity tests showed that all the tested isolates from identified species were pathogenic on cabbage leaves, although there were statistically significant differences in virulence of the tested isolates. A. brassicicola isolates had the highest virulence and A. arbusti and A. vaccinii isolates had the lowest virulence. Isolates belonging to other species had moderate virulence. Except A. brassicicola which had been previously reported from cabbage in Iran, all other seven species are reported for the first time from cabbage as the causal agents of black spot disease. Also, A. arbusti, A. perangusta and A. vaccinii are reported as new species for Iran mycoflora.