First Report in Washington State of the Teleomorph of Stemphylium vesicarium, the Causal Agent of Purple Spot of Asparagus. D. A. Johnson, IAREC, Prosser, WA 99350. Plant Dis. 71:192. Accepted for publication 10 November 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0192A.
Purple spot of asparagus (Asparagus officinalis L.), caused by Stemphylium vesicarium (Wallr.) Simmons, was first identified in Washington in 1982, but the perfect stage of the pathogen was not found then. During the winter of 1985-1986, pseudothecia (0.25-50 mm diam.) were found on the surface of asparagus stems and branches throughout the asparagus-growing areas in Washington. Asci were bitunicate and ascospores were muriform and darkly pigmented. Pseudothecia were identified as Pleospora allii (Rab.) Ces. & de Not. Single ascospore cultures yielded conidiophores and conidia identified as S. vesicarium. Shoots of potted asparagus were either wounded with air-blown sand (I) or not wounded, inoculated with ascospores collected from pseudothecia, and placed in a mist chamber for 72 hr, then in the greenhouse. Lesions typical of those caused by S. vesicarium (1,2) developed on both wounded and nonwounded shoots. S. vesicarium was isolated from these lesions. References: (I) D. A. Johnson and J. D. Lunden. Plant Dis. 70:419,1986. (2) M. L. Lacy. Plant Dis. 66: 1198, 1982.