Abstract
A new disease of European pear (Pyrus communis L. var. sativa de Candolle), causing black leaf spot and bud rot, was found on cv. Le Lectier in orchards in Niigata Prefecture, Japan, in 1993. Black spot lesions on cv. Le Lectier leaves began to appear in late May and the disease developed rapidly in summer. Severe symptoms are characterized by defoliation of young leaves. The same disease was also observed on cv. General Leclerc. Alternaria sp. was consistently isolated from the diseased leaves and buds. Based on morphological characteristics, the fungus was identified as A. alternata (Fries:Fries) Keissler. In inoculation tests with conidia, the fungus was pathogenic on the original hosts, cvs. Le Lectier and General Leclerc, and re-isolated from lesions of the inoculated leaves. European pear cvs. Ballade, Koshisayaka, La France, Marguerite Marillat and Silver Bell, and Japanese pear cv. Nijisseiki were not affected by the fungus. This is the first report on a disease of European pear caused by A. alternata. Therefore, black spot (kokuhanbyo in Japanese) of European pear was proposed for the name of the new disease.
