The role of Pythium species in yield decline in Southern cane growing districts : SRDC final report BS80S

Abstract

Yield decline has been demonstrated in all established canegrowing regions of Queensland. Field and glasshouse studies with soil fumigants have shown that yield decline is largely caused by soilborne biological factors. Some evidence suggests that these factors are specific to sugarcane. Yield increases of 30-40% in field experiments with methyl bromide have been obtained in all canegrowing regions. If only 10% of this response could be obtained by partial control of deleterious soilborne microorganisms, returns to the Queensland sugar industry would be increased by more than $30m annually. Pythium species have been responsible for significant yield loss of sugarcane in Louisiana. Limited examinations of soils from the southern canegrowing districts of Queensland has shown that highly pathogenic Pythium species are present. These fungi cause severe damage to cane roots under cold, wet conditions and may be involved in poor ratooning under trash blankets in southern districts. While these fungi may cause large yield losses in central and southern canegrowing regions, their distribution and severity and the need for controls have not been adequately defined. This report briefly outlines the results of a survey of southern Australian canegrowing districts for Pythium species and glasshouse and field experiments to determine the yield losses which can be attributed to Pythium species. Detailed experimental methods and results can be found in the Master's Thesis by G Pegg entitled "The role of Pythium species in yield decline in southern sugarcane growing districts of Australia" which was the result of research conducted in this project.