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First Report of Sclerotinia sclerotiorum on Buckwheat (Fagopyrum esculentum) in Italy

In each of two fields of buckwheat (Fagopyrum esculentum L.) grown in Benevento Province (southern Italy), 60 to 70% of the plants developed severe root and crown rot. Symptoms included irregular, water-soaked spots on stems that were eventually covered with cottony mycelia as the lesions enlarged. Black sclerotia usually developed within the mycelium. The fungus was isolated on potato dextrose agar and 2% water agar. On the basis of colony morphology, including the production of black sclerotia (1), the fungus was identified as Sclerotinia sclerotiorum (Lib.) De Bary. The identity of the fungus was confirmed by near exact identity of internal transcribed spacer sequences (99%) with two isolates of S. sclerotiorum in GenBank (Accession Nos. Z73800 and Z73799). Pathogenicity of the fungus on buckwheat was evaluated by transplanting 20 20-day-old healthy plants in a mixture of soil and fungal inoculum (0.5% of wet millet seeds colonized by four isolates of S. sclerotiorum). Lesions on crowns and roots developed after 12 days and sclerotia appeared approximately 20 days later. No symptoms developed on noninoculated plants. Reisolation from inoculated plants yielded colonies of S. sclerotiorum. To our knowledge, this is the first report of S. sclerotiorum on buckwheat in Italy. The high incidence and severity of the disease may be limiting factors in the development of buckwheat as an alternative crop of tobacco in southern Italy.

Reference: (1) J. E. M. Mordue and P. Holliday. Sclerotinia sclerotiorum. No. 513 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1976.