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Post-Harvest Pathology and Mycotoxins

Conidiogenesis of Marssonina panattoniana and its Potential as a Serious Postharvest Pathogen of Lettuce. H. E. Moline, Research Plant Pathologist, Horticultural Crops Marketing Laboratory, Agricultural Marketing Research Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705; Flora G. Pollack, Mycologist, Plant Protection and Quarantine Programs, APHIS, U.S. Department of Agriculture, Beltsville, Maryland 20705. Phytopathology 66:669-674. Accepted for publication 11 November 1975. DOI: 10.1094/Phyto-66-669.

The symptoms of a destructive leaf disease of lettuce (Lactuca sativa) which appeared in marketing channels, and the morphological characteristics of the causal fungus (Marssonina panattoniana) on the host and in culture are described. The disease is characterized by yellow to brown sunken lesions on the veins, and shot-hole lesions on the leaf blades. Harvested mature lettuce inoculated with a conidial suspension showed symptoms of infection after 10 to 17 days at 7 to 18 C. Light and scanning electron microscope studies revealed the absence of acervuli and the presence of annellations on the conidiogenous cells (conidiophores), raising doubt as to the taxonomic position of the fungus in the genus Marssonina.