The discovery of gumming disease of sugarcane in Australia

Sugarcane is one of Australia’s major agricultural industries, with approximately 95% of the crop being grown in Queensland and the remainder in northern New South Wales. In the last decade of the nineteenth century, cane growers in northern New South Wales started to see a new disease that resulted not only in the death of plants but also in difficulties in the extraction of sugar. Theories about the cause abounded, but investigations by the New South Wales vegetable pathologist Nathan Cobb revealed that the disease, previously unknown to the world, was caused by a microbe in the creamy ‘gum’ that could be commonly found in the vascular tissues of affected stalks. He named the organism Bacillus vascularum (now known as Xanthomonas axonopodis pv. vasculorum). For some time after, the disease was known as ‘Cobb’s gumming disease of sugarcane’. The Australian bacteriologist Robert Greig-Smith was not convinced that Cobb had conclusively demonstrated that B. vascularum was the culprit, mainly because he did not satisfy Koch’s Postulates. However, the American bacteriologist Erwin Frink Smith came to Cobb’s rescue when he proved beyond doubt that B. vascularum was to blame. The disease is now known simply as ‘gumming disease of sugarcane’.