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Survival of Mucor piriformis on Artificially Inoculated Fruit Endocarps of Prunus persica. Themis J. Michailides, Assistant research plant pathologist, Department of Plant Pathology, University of California, Berkeley/Kearney Agricultural Center, Parlier, CA 93648; Phytopathology 80:174-181. Accepted for publication 28 August 1989. Copyright 1990 The American Phytopathological Society.. DOI: 10.1094/Phyto-80-174.

In laboratory tests, sporangiospores of Mucor piriformis, isolates CA from California and CH from Chile, added to peach and nectarine endocarps and then partially buried in wet (?30 kPa matric potential) and dry (?1.3 ? 105 kPa matric potential) soil survived longer at 0 and 10 C than at 27 and 33 C. More sporangiospores survived on endocarps buried in dry than in wet soil. Survival of sporangiospores declined over time in a pattern described by polynomial equations in wet soil at all temperatures and in dry soil only at 33 C. Both isolates grew and sporulated on autoclaved endocarps incubated in moisture chambers at 0, 10, and 21 C, but not on those incubated at 27 or 33 C. An agar medium made from endocarp washings favored germination of sporangiospores and significantly increased growth and sporulation of M. piriformis compared with plain water agar. Mummified peaches and nectarines artificially inoculated with isolates CA and CH of M. piriformis were exposed to winter and summer soil conditions in the field. Recovery of the fungus during fall and winter months (October to March) was 100%. Approximately 5 mo from the time the endocarps were buried in the soil, decline of propagules on the endocarps lacking fruit tissues was exponential for both isolates, with more propagules of the CA isolate surviving than the propagules of the CH isolate after 1 yr. Chlamydosporelike structures were found in hyphae, and sporangiophores developed in decayed mesocarp tissues. More than 75% of the colonies of M. piriformis that grew from propagules on endocarps originated from sporangiospores.

Additional keywords: postharvest pathogen, psychrophilic fungus.