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Ecology and Epidemiology

Colonization, Sporulation, and Persistence of Mucor piriformis in Unamended and Amended Orchard Soils. Themis J. Michailides, Former graduate research assistant, Department of Plant Pathology, University of California, Davis 95616; Joseph M. Ogawa, Professor, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 77:257-261. Accepted for publication 17 July 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-257.

The behavior of two isolates [California isolate (CA), Chile isolate (CH)] of Mucor piriformis was studied in orchard soils that were autoclaved or nonautoclaved and amended with a suspension of soil microbes, organic matter, or used without amendments. In nonautoclaved or autoclaved soils amended with soil microorganisms, M. piriformis failed to colonize the soil. However, in soils amended with organic matter and soil microorganisms the fungus grew and sporulated. Nonautoclaved leaves of peach (Prunus persica), ryegrass (Lolium perenne), and chickweed (Stellaria media) also supported sporangiospore germination, growth, and sporulation by M. piriformis. Sporangiospores of M. piriformis did not germinate and grow in nonautoclaved soil; in contrast, they germinated and grew in autoclaved soil amended or unamended with crushed peach leaves. When soil microorganisms were added to autoclaved soil, growth of M. piriformis was restricted to the immediate vicinity of the spore inoculum. Glucose amendments at levels of 7.5300 μg per gram of dry soil favored sporangiospore germination in autoclaved but not in nonautoclaved soil. Germ tubes of sporangiospores that germinated in soil had unusual septation, fragmentation, and retraction of their protoplast and lysed after 15 days in soil.

Additional keywords: postharvest pathogens, saprophyte.