Wattle gall—the quintessential Australian plant disease

Abstract

Acacia (the wattles) is the largest genus of plants in Australia and its species occupy almost every habitat in the country. Hard galls on the branches, phyllodes and flower parts of wattle trees were noticed from the very early days of British colonisation, but their causes were unknown. Some insects were believed to be involved, but they were not the only cause of wattle galls. In 1889, the Italian mycologist Pier Andrea Saccardo described the rust fungus Uromyces tepperianus from the galls on Acacia salicina, and later, the Victorian government vegetable pathologist, Daniel McAlpine transferred the species tepperianus to his new genus Uromycladium which also included six new species. A total of 28 valid species of Uromycladium, most endemic to Australia, are currently described. Several species of Uromycladium were somehow introduced into South Africa and countries in southeast Asia where they cause significant losses in Acacia plantations, while others are used as biocontrol agents for invasive Acacia species. Short biographies of two of the early collectors of rust galls, the South Australian naturalist and later entomologist Johann Gottlieb Otto Tepper and the Victorian plant pathologist Charles Clifton Brittlebank are also presented.