Identification of seed-borne fungi in summer (Cucurbita pepo) and winter (Cucurbita moschata) pumpkins of Turkey

This study used seeds from five different summer pumpkin (Cucurbita pepo L.) cultivars (Çağlayan, Mert Bey, Sena Hanım, TG22, and TG38) and seeds collected from fruits in ten different provinces in Turkey where winter pumpkins (Cucurbita moschata Duch.) were cultivated. The seed coat and embryo were cultured and the seed-borne fungi were identified. Allophoma labilis and Didymella americana were detected in seeds (seed coat and embryo) of the cvs. Çağlayan and Mert Bey only, respectively. The seeds of both summer and winter pumpkins were contaminated with Alternaria alternata, Fusarium equiseti and Fusarium proliferatum, though their incidence varied depending on cultivar, province and seed parts. All species caused root and crown rot in seedlings in pathogenicity tests. Disease severities were caused by A. labilis, A. alternata, D. americana, F. equiseti and F. proliferatum at rates of 37.14–49.64%, 31.78%-42.50%, 31.29%, 14.17–50.00% and 25.14–51.07%, respectively. Colonial growth on different media, morphological and molecular characterization of the most pathogenic isolates from each species were defined. This is the first report in Turkey of A. labilis and D. americana in seeds of C. pepo, and Alternaria alternata, F. equiseti and F. proliferatum in seeds of both C. pepo and C. moschata, as well as the first pathogenicity record for these species by seed inoculation.