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Postharvest Pathology and Mycotoxins

Postharvest Biological Control of Gray Mold of Apple by Cryptococcus laurentii. R. G. Roberts, U.S. Department of Agriculture, Agricultural Research Service, Tree Fruit Research Laboratory, 1104 N. Western Ave., Wenatchee, WA 98801; Phytopathology 80:526-530. Accepted for publication 27 November 1989. 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, 1990. DOI: 10.1094/Phyto-80-526.

Cryptococcus laurentii is a basidiomycetous yeast that occurs naturally on apple leaves, buds, and fruit. Puncture wounds in surface-disinfested cultivar Golden Delicious apple fruit were treated with phosphate buffer, cell suspensions of C. laurentii, or benomyl, then inoculated with 2 ? 10⁴ conidia per milliliter of Botrytis cinerea and incubated 12 days at 5, 10, 15, or 20 C. Treatment of wounds with washed cells of C. laurentii at 10⁴?10⁵ cells per wound effectively reduced or prevented development of decay by B. cinerea at all temperatures compared with controls and was comparable in effectiveness to preinoculation application of benomyl at the postharvest label rate. Treatment of wounds with cell-free culture filtrates of C. laurentii were not effective in preventing decay and resulted in greater lesion diameters than in inoculated, buffer-treated wounds. As the interval between wounding and inoculation with B. cinerea increased from 0 to 72 hr, susceptibility of wounds to decay by B. cinerea decreased. Population densities of C. laurentii in wounds increased rapidly, even at 5 C, and were never associated with necrosis or discoloration of host tissue.