SURVIVAL OF SUGARCANE SMUT TELIOSPORES UNDER SOUTH EAST QUEENSLAND CONDITIONS

THE survival of sugarcane smut teliospores in the field is an important factor in the epidemiology of the disease and is important when developing strategies to limit the spread of the disease between quarantine districts. A study was conducted at BSES Limited Southern Sugar Experiment Station and the smut research farm at Kinkuna, 20 km south of Bundaberg, to investigate the survival of the smut fungus Ustilago scitaminea. We investigated the survival of teliospores in the field when buried in the soil, placed on the soil surface or in sugarcane trash, or held 1 m above the soil surface. The longevity of teliospores when attached to material, as would be experienced when a person brushes against a smut-infected plant, was compared with that of teliospores held in a paper bag. Smut teliospores were placed in soil with various soil moisture levels (0%, 10%, 20% and 30%) in the laboratory to determine the survivability at various soil moisture regimes. Field conditions had a large effect on survival. Teliospores on whips buried in soil failed to germinate after 12 weeks, teliospores mixed in sugarcane trash and those placed on the soil surface survived approximately six months, and teliospores on whips held at 1 m above ground survived for more than six months. Teliospores on whips in paper bags and on cloth maintained at room temperature survived for up to four months. Teliospores of the smut fungus had completely lost viability after 12 weeks in soil at 30% and 20% soil moisture. In soil at 10% moisture, teliospores survived for up to four months. Approximately 25% of teliospores remained viable in soil with 0% soil moisture after six months. These results suggest that teliospores of sugarcane smut can only survive for a few months at high soil moisture level (>10%) or when buried in soil. However, teliospores of the smut fungus have potentially greater longevities when maintained in dry environments.