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Foliar Blight of Bigflower Vetch Caused by Ascochyta fabae f. sp. vicia . K. T. LEATH, USDA-ARS, Pasture Systems and Watershed Management Research, University Park, PA 16802. R. E. DeGREGORlO and R. A. ASHLEY, Department of Plant Science, University of Connecticut, Storrs 06269. Plant Dis. 78:637-639. Accepted for publication 8 February 1994. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source The American Phytopathological Society, 1994. DOI: 10.1094/PD-78-0637.

Bigflower vetch (Vicia grandiflora var. kitaibeliana) is a winter-annual legume developed for use in pastures and as a winter cover crop in specialized situations. During evaluation in a rotation experiment in Connecticut, bigflower vetch became severely diseased by a foliar blight. Symptoms consisted of reddish brown spots with tan centers on leaves. Spots were oval and often coalesced lo form larger blotches. A fungus identified as Ascochyta fabae was isolated from diseased tissues, and this fungus induced leaf spots plus necrosis of stems, petioles, and tendrils on bigflower vetch by artificial inoculation. The fungus caused leaf spots (<2 mm in diameter) on V.faba, V. hirsuta, and V. tenuifolia, minor leaf flecking on four other legume species, and no symptoms on 54 other species. Only bigflower vetch was susceptible. Because of the very narrow host range of the form of A. fabae from bigflower vetch, rotation of bigflower vetch with other legumes may not be problematic. This strain of A. fabae has the potential, however, to greatly impair the productivity of bigflower vetch in the northeastern United Slates and possibly elsewhere. Ascochyta fabae f. sp. vicia is proposed to describe the specialized form of the fungus pathogenic to bigflower vetch.