Growth and Sporulation of Species and Isolates of Cylindrocladium in Culture

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Abstract
Several species of Cylindrocladium [C. scoparium, C. ilicicola, C. macrosporum, C. penicillioides, C. heptaseptatum, C. pteridis, C. quinqueseptatum, C. avesiculatum, C. ellipticum and C. theae], comprising 58 isolates, were studied in culture to determine their trophic and sporulation responses to various nutrients and to light. C. avesiculatum and 2 isolates of C. floridanum were thiamine deficient, whereas all other species and isolates tested synthesized essential vitamins. All C sources tested were utilized with remarkable similarity by all isolates investigated. All N sources tested were utilized well, some more rapidly than others, by all isolates, although growth was greater and more rapid when casein hydrolysate was the N source than when KNO3 was used. Production of conidia was not greatly influenced by any of the sporulating isolates on any of the C and N sources. Perithecia were not formed on ammonium sulfate (unless buffered near neutrality) or malt extract media. Most species sporulated asexually better when incubated under near-UV and blue radiation, except C. citri which responded to red and far-red radiation, and C. parvum which was not affected by light. C. floridanum and C. crotalariae required radiation for formation and development of perithecia. Perithecial initials were observed in dark-grown cultures of C. floridanum. Production of microsclerotia by 8 isolates occurred on all 5 natural media tested, glucose-malt agar being the poorest. Glucose-lima bean agar was an excellent medium for maximum mycelial growth, microsclerotial production, as well as for inducing numerous conidia and perithecia. Glucosee-asparagine is recommended as the synthetic medium and choice for taxonomic work, because it provides excellent growth and sporulation of all species investigated. Conidial septation varied with the species but was not observed to be influenced by the medium. Morphology of the apical veiscle of the conidiophore was variable among species and often within the same isolate, thus rendering this characteristic untenable for delineating species.