LONG-TERM STORAGE OF USTILAGO-TRITICI

An extensive collection of isolates Of Ustilago tritici from around th e world is maintained at the Cereal Research Centre. As the collection size increases, however, the time and effort needed to maintain the c ollection becomes greater,as does the need for a good technique for lo ng term storage of U. tritici. Race T2 of U. tritici was inoculated to spikelets of wheat in February 1976. The matured inoculated heads wer e thrashed and the seed stored in a desiccator with silica-gel at -15 degrees C. Every 2 years, 60 seeds were removed and planted to determi ne viability and proportion of infected adult plants. Between 57 and 8 3% of the seed produced adult plants, and the percent of infected plan ts ranged between 56 and 98% during the 20 years. There was no signifi cant change in seed germination over rime, but there was a positive re lationship (P < 0.0664, R-2 = 0.452) between the time of storage and t he arcsine of the proportion of smutted plants. Storage of U. tritici in infected seed at -15 degrees C and low relative humidity is an effi cient method for long-term storage of this fungus.