Disease Note.

First Report of Ascochyta rabiei Causing Ascochyta Blight of Garbanzo in California. P. Guzman, Department of Plant Pathology, University of California, Davis 95616 . R. M. Davis, R. L. Gilbertson, Department of Plant Pathology, University of California, Davis 95616, and S. N. Smith and S. Temple, Department of Agronomy and Range Science, University of California, Davis 95616. Plant Dis. 79:82. Accepted for publication 17 November 1994. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0082C.

A severe blight of garbanzo (Cicer arietinum L.) plants was observed in May 1994 on experimental lines growing at the University of California, Westside Field Station in Fresno County. Thirty percent of the 1.5-acre field was severely infected after a period of cool and rainy weather. Symptoms included tan to brown lesions on leaves, stems, and pods and signs were brown to black pycnidia immersed in host tissue and arranged in concentric rings within the lesions. Conidia were straight, hyaline, and usually nonseptate. Based on the morphological characteristics of the fungus from infected plants and pure culture, it was identified as Ascochyta spp. To complete Koch’s postulates, a monosporic fungal culture was grown on potato-dextrose agar. In two separate experiments, 15-day-old garbanzo plants were sprayed with a suspension of conidia (2 ? 104 conidia per milliliter) from the monosporic culture and covered with plastic bags for 5 days. Noninoculated plants served as controls. Lesions similar to those observed on the freld-infected plants developed on stems, petioles, and leaves 12 days after inoculation. Control plants were symptomless. The fungus was reisolated from diseased tissue and was morphologically identical to the original monosporic isolate and, thus, was identified as A. rabiei (Pass.) Labrousse. This seedborne pathogen represents a potential threat to the 15,000 acres of garbanzo grown in California. Ascochyta blight of garbanzo was first reported in the Western Hemisphere in Canada in 1974, and later in the United States in Washington in 1983 and Idaho in 1985 (1,2). This is the first report of A. rabiei infecting garbanzos in California.