Poster Presentation Science Protecting Plant Health 2017

Epidemiology and impact of myrtle rust (Austropuccinia psidii) in lemon myrtle (Backhousia citriodora) plantations (#153)

Emily Lancaster 1 2 , Geoff Pegg 2 3 , David Lee 4 , Andre Drenth 1
  1. The University of Queensland, St Lucia, Queensland, Australia
  2. Plant Biosecurity Cooperative Research Centre, Canberra, ACT, Australia
  3. Department of Agriculture and Fisheries, Dutton Park, Queensland, Australia
  4. University of the Sunshine Coast, Sippy Downs, Queensland, Australia

Lemon myrtle (Backhousia citriodora) is a native Australian species whose leaves contain oil with the highest citral content (<98%) of any known plant in the world.  Steam distillation is used to extract essential oil from the leaves and this is used in aromatherapy products, cosmetics and toiletries, and as a food flavouring.  The leaves are also dried and milled for use in teas or as a spice.  Growth of this Australian native food industry has increased substantially in recent years, in both Australian and overseas markets.  However, the introduction of the rust fungus Austropuccinia psidii (A. psidii) into Australia in 2010 has jeopardized its expansion and success.  Limpinwood, the widely used commercial lemon myrtle cultivar, is highly susceptible to A. psidii and yield losses have been estimated to be up to 70% in plantations not applying fungicides.  Glasshouse studies and field trials in a commercial lemon myrtle plantation in New South Wales were undertaken to gain an understanding of: (1) factors influencing the susceptibility of lemon myrtle to infection by A. psidii and host colonisation; (2) the influence of climatic factors and inoculum density on the incidence and severity of A. psidii in lemon myrtle; and (3) the effect A. psidii infection has on the growth and yield of lemon myrtle, including the impact on essential oil properties.  Our research will and enable the development of a forecasting system for this disease so more informed, effective and economically feasible management decisions can be made, particularly regarding fungicide applications.  It will also provide an economic evaluation of the impact A. psidii is having on the commercial production of lemon myrtle and detailed information concerning levels of resistance in cultivars of lemon myrtle.