COMPARATIVE PATHOGENICITY OF COPRINUS-PSYCHROMORBIDUS MONOKARYONS AND DIKARYONS ON WINTER-WHEAT, ALFALFA, GRASS, AND POME FRUIT

Strains of a low temperature basidiomycete (LTB = Coprinus psychromorbidus) were evaluated for pathogenicity under controlled conditions on winter wheat, alfalfa, and Kentucky bluegrass at -3C and 0.5° C, and in apple and pear fruits at 2°C. A sterile LTB (LRS-013) strain reduced percent survival and dry weights of all host species at -3°C and caused fruit rot at 2°C. A fruiting C. psychromorbidus dikaryon and its derived monokaryons were slightly pathogenic to alfalfa and nonpathogenic to winter wheat, bluegrass, and pome fruits. Monokaryons and dikaryons of the fruit rot low temperature basidiomycete (FRLTB) originally isolated from pome fruit in storage were similar to the LRS-013 strain in host range and optimum temperature for pathogenicity. All strains except LRS-013 were non-pathogenic to Kentucky bluegrass. None of the strains reduced percent survival or dry weights of wheat and alfalfa at 0.5°C but several caused differences in visual disease severity ratings. The optimum temperature for growth and pathogenicity of LTB and FRLTB strains in Golden Delicious apples was 15°C. FRLTB monokaryons did not differ from dikaryons in optimum temperature for pathogenicity and in relative pathogenicity on the different hosts. The optimum temperature for pathogenicity by strains of low temperature basidiomycetes originating from widely varying sources on different hosts is discussed. © 1990 Taylor & Francis Group, LLC.