1981 Volume 47 Issue 4 Pages 457-463
Serial transfer of Pyricularia oryzae on PSA slant during 4 years caused decrease of aggressiveness and loss or acquirement of virulence. Monoconidialy re-isolated lines from isolate which appeared as not to be varied were, in some cases, heterogeneous in virulence and/or aggressiveness. Alteration was affected by frequency of transferring, volume of culture medium and constituents of medium. Frequent renewal of medium was commonly unfavorable. Although synthetic medium was better than PSA, the variation also occurred at 3rd year of storage. Rice node method is better than serial transfer on PSA slant. Around 60-70% stocks, however, died or contaminated during storage in -10 C for 4-10 years. A simple and reliable method for preservation of this fungus was investigated. Dried mycelial discs were viable, at least, for 5 years of preservation in small vials desiccated with silica gel under 5 to -10 C.