A matter of where and when—the appearance of Late Blight of potato in Australia

Abstract

Late Blight, also called Irish blight and brown rot, devastated potato crops in Ireland and countries in Europe in the 1840s, and led to famines, deaths, and the emigration of tens of thousands of poor farmworkers. The outbreaks were blamed on many factors, but finally it was demonstrated that the causal agent was an oomycete (water mould) Phytophthora infestans. The Queensland Government Entomologist and Vegetable Pathologist, Henry Tryon, claimed that he made the first discovery of Late Blight in Australia, on leaves and tubers of potato collected in May 1909 around Brisbane. Within three months, the disease was found in all Australian states. Tryon believed that the Queensland outbreak was caused by Phytophthora-infected planting tubers obtained from Tasmania, which growers and the government in that state initially refused to acknowledge. The Victorian Vegetable Pathologist, Daniel McAlpine, initially agreed with the Tasmanians, but later admitted that he had identified Ph. infestans in Tasmanian potato crops. A herbarium specimen of potato leaves collected in 1900 in Victoria, examined over a century later, was found to be infected with Phytophthora infestans. All the ruckus that ensued after Tryon’s discovery was unnecessary; it was really a matter of where and when.