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Postharvest Pathology and Mycotoxins

Studies with Mucor Species Causing Postharvest Decay of Fresh Produce. W. L. Smith, Jr., Research plant pathologist, Horticultural Crops Marketing Laboratory, Agricultural Marketing Research Institute, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Beltsville, MD 20705; H. E. Moline(2), and K. S. Johnson(3). (2)(3)Research plant pathologist and laboratory technician, respectively, Horticultural Crops Marketing Laboratory, Agricultural Marketing Research Institute, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Beltsville, MD 20705. Phytopathology 69:865-869. Accepted for publication 6 March 1979. 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, 1979. DOI: 10.1094/Phyto-69-865.

Fifteen isolates of Mucor piriformis from peaches or nectarines and five of M. circinelloides from tomatoes were studied. Sporangiospores of M. piriformis isolates germinated and formed normal germ tubes at temperatures from 0 to 24 C but not at 27 C. At each temperature, the diameter of the spores increased before germination. At 27 C, the spore diameter swelled to six to eight times that of the resting spore. When germination occurred at 27 C, the germ tubes were abnormally swollen and often grotesquely shaped. Exposure to 27 C for 7 or 10 days prevented germination when the isolates were later transferred to 18 C. Spores of M. circinelloides isolates germinated at temperatures up to 40 C and did not swell appreciably. In inoculative studies, both Mucor spp. caused decay of stone fruits, apples, pears, oranges, sweet potatoes, tomatoes, carrots, bell peppers, celery, and lettuce but not of white potatoes. Both green and mature peaches and tomatoes decayed. M. piriformis was the more pathogenic of the two species. Cultures of M. piriformis and M. circinelloides have been deposited with the American Type Culture Collection.