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Production of Microsclerotia by Species of Cylindrocladium. Barry B. Hunter, Professor, Department of Biological Sciences, California State College, California, Pennsylvania 15419; H. L. Barnett, Professor of Mycology, West Virginia University, Morgantown, West Virginia 26506. Phytopathology 66:777-780. Accepted for publication 12 December 1975. DOI: 10.1094/Phyto-66-777.

To determine factors that affect production of microsclerotia, five species of Cylindrocladium (C. scoparium, C. crotalariae, C. floridanum, C. ilicicola, and C. parvum) were studied to determine factors that affect production of microsclerotia. The most favorable temperature range for growth was 24-28 C. The C/N ratio of the substrate was most important with maximum numbers of microsclerotia formed at ratios of 40:1 and 100:1; fewer were formed at lower ratios on agar media and in sand culture. Potassium nitrate was a good nitrogen source at favorable ratios, but poorer than casein hydrolysate at unfavorable ratios. L-tyrosine as a sole source of C and N was excellent for formation of microsclerotia. Straw and sawdust also were good substrates for microsclerotia formation. Evidence suggests that the practice of mulching seed beds known to harbor Cylindrocladium with straw, sawdust, or other high-carbon products, may cause a significant increase in numbers of microsclerotia.

Additional keywords: flotation sieving, microsclerotia, vesicle.