YIELD LOSSES FROM SUGARCANE SMUT: INDICATIONS FROM HERBERT MILL DATA AND FROM INDIVIDUAL CROP ASSESSMENTS

SUGARCANE smut has been increasing in both extent and severity within the Australian sugarcane industry since the initial incursion was detected in 2006. Smut severity is high in the Herbert district, probably higher than any other district in Queensland. In 2009–2010 the yield losses have been increasing, particularly in crops of the most highly susceptible varieties. Losses of >25% in individual crops illustrate the potential for smut to reduce yield. Analysis of Herbert factory data suggests a trend to decreasing yields in the most susceptible varieties in the last couple of years. However, average yield for these varieties has not plummeted and we postulate two contributing factors: (i) severely affected crops of highly susceptible varieties have been terminated by farmers in response to industry recommendations, so avoiding disastrous yields (ii) yield losses have not been as great as expected in some crops where smut infestation was high but severity moderate. The effect of smut on average district yields in Queensland will not be huge because the sugarcane industry has been proactive in transitioning to resistant varieties and the yield of these replacement varieties has generally been excellent.