Recovery of Native Plant Communities following Control of Terracina Spurge (Euphorbia terracina): Three Case Studies from South-west Western Australia

Abstract

Terracina spurge or Geraldton carnation weed (Euphorbia terracina) is an invasive weed that impacts native plant communities across southern mainland Australia and in the United States (USA), including southern California and Pennsylvania. There are, however, few published accounts of appropriate control techniques or recovery of native vegetation following removal of this species. We report here on the results of three adaptive management projects investigating effective control of Terracina Spurge and subsequent recovery of Banksia woodlands, coastal shrublands, and sedgeland communities in the Swan Coastal Plain bioregion, south-west Western Australia. In Banksia woodlands the herbicide metsulfuron-methyl (600g/kg) (Brush-Off^®) in combination with hand removal of adult plants was effective at controlling Terracina spurge. Although there was some initial off target damage to native flora, after five years of repeated application the Banksia woodland within the treated area is regenerating. In sedgelands of the Holocene dune swales and in coastal shrublands 750g/kg triasulfuron (Logran^®) was very effective, reducing Terracina spurge populations significantly in the first two years. The treatment resulted in little damage to native flora. At both sites a significant difference in species abundance between years was attributed mostly to a decrease in the cover of Terracina spurge but also an increase in cover of several species of native flora. The results indicate triasulfuron is an effective tool for the management of Terracina spurge in coastal plant communities potentially leading to the protection and restoration of significant areas of the conservation estate within the Swan Coastal Plain bioregion and beyond.