Corynespora cassiicola causes target leaf spot on several plant hosts including cucurbits. The objectives of this study were to evaluate the pathogenicity of 15 isolates of C. cassiicola obtained from several hosts, to the Japanese cucumber hybrids (Cucumis sativus), as well as to evaluate the severity of the disease in greenhouse. It was observed that only three isolates from cucumber and one isolate from pumpkin were able to infect the four cucumber hybrids. Only 'Natsubayashi' and 'Tsuyataro' were infected by the two isolates from soybean and one isolate from tomato. The isolates from cucumber were significantly more aggressive than isolates from other hosts. Differences were also observed in susceptibility among the cucumber hybrids to C. cassiicola. 'Tsuyataro' was more susceptible than the other hybrids. Such differences in aggressiveness of the isolates and in the susceptibility of the hosts suggest a longer adaptation of C. cassiicola on cucurbits.
Cucumis sativus; target leaf spot
