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Isolation of Cylindrocladium from Soil or Infected Azalea Stems with Azalea Leaf Traps. R. G. Linderman, Plant Pathologist, Plant Science Research Division, ARS, USDA, Beltsville, Maryland 20705; Phytopathology 62:736-739. Accepted for publication 13 February 1972. DOI: 10.1094/Phyto-62-736.

Healthy, detached azalea leaves, inserted into infested soil or into infected azalea stems, were used to trap and identify several species of Cylindrocladium. Using this method, C. scoparium and C. theae were recovered from infected azalea stems, often when direct plating methods failed. These two species, plus C. floridanum, C. ilicicola, C. crotalariae, and C. quinqueseptatum were successfully trapped from artificially infested field soil or greenhouse (GH) soil mix, but C. parvum and an undescribed Cylindrocladium sp. were not. Phytophthora cinnamomi was not recovered either from soil or infected azaleas by this method. By means of the leaf trap method, C. scoparium was found to persist in artificially infested vermiculite or perlite for 2 months, and in field soil or GH soil mix for at least 5 months (the latter being infested with as low as 9 conidia/g soil). Cylindrocladium floridanum was trapped from three naturally infested field soils and one artificially infested field soil diluted with uninfested soil from 13 down to ca. 3 microsclerotia/g soil.

Additional keywords: soil assay, azalea diseases, survival in soil, species identification.