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Purple Spot: A New Disease of Young Asparagus Spears Caused by Stemphylium vesicarium. M. L. Lacy, Professor, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824. Plant Dis. 66:1198-1200. Accepted for publication 11 August 1982. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-1198.

Stemphylium vesicarium was isolated from about 80% of small (12 mm) elliptical purplish spots on freshly harvested asparagus (Asparagus officinalis) spears. Alternaria sp. was isolated from about 20% of these spots. The lesions were not associated with any major breakdown of tissue, but large numbers of lesions made the spears unsightly and unacceptable for fresh market or processing sales. In inoculation experiments, S. vesicarium was pathogenic only on wounded tissue. Alternaria sp. was not pathogenic on either wounded or unwounded tissue. In the field, asparagus was probably predisposed to S. vesicarium by sand-blasting or similar injuries.