Williams_D_Peri-Urban environments: the x factor for plant pests and diseases


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Beyond the Edge: Australia's First National Peri-urban Conference
La Trobe University
Oct 2013

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Williams_D_Peri-Urban environments: the x factor for plant pests and diseases

  1. 1. Peri-urban environments: The ‘X Factor’ for plant pests and diseases David Williams, Jacky Edwards, Greg Lefoe, Ian Porter, Brendan Rodoni & Alan Yen
  2. 2. What am I talking about? • • • • Definitions of per-urban Implications for biosecurity Some case studies Concluding remarks
  3. 3. Peri-urban areas • Delineation difficult • Victoria – Riverland – Melbourne hinterland – Most of eastern Victoria Aslin et al (2004) Bureau of Rural Resources, Canberra What about Geelong, Bendigo, Ballarat, Wodonga, Shepparton, Wangaratta, Horsham, etc?
  4. 4. Mosaic • Urban and rural residential • Commercial and “lifestyle” hobby farms • Water catchments and storage • Other rural industries, including intensive animal production • Nature reserves • Recreation facilities • Transport routes and hubs
  5. 5. Biosecurity • Protection of people, farms, animals and plants from entry and spread of unwanted exotic animals, pests, diseases and weeds (Maller et al . 2007. Biosecurity and small landholders in peri-urban Australia. Bureau of Rural Resources, Canberra ) • Global peri-urban focus on animal diseases that could impact on humans but virtually none on plant pests & diseases • Hobby farms and consumer demand – New animal and plant industries – New invasive species – New pathways to infest commercial farms and environment • Neglected farms
  6. 6. Biosecurity 2 • • • • • • • Border protection Containment & eradication Pest infested zones Areas of low pest prevalence Pest free areas of production Pest exclusion zones Pest risk zones
  7. 7. Case study: Fireblight • Bacterial • Major threat to pome fruit, particularly major Australian varieties of apple and pear • Reported in RBG Melbourne 1997 • 1200 host plants removed • Many high value plants • Compensation • Awareness program
  8. 8. Case study: Plum pox • Virus of stone fruit • Infects apricots, plums, peaches, nectarines, ornamental prunus • No cure except destruction of trees • Eradicated in Pennsylvania 1999 • 300 sq.mile quarantine zone • 1600 acres removed • all prunus within 500m radius of infected tree • Failure in Canada 2000 • high density of Prunus • adopted threshold level of infection rather than removal of trees around infected trees
  9. 9. Case study: grapevine leaf rust • Private garden grapevine Darwin 2001 • Surveys within 15kms found 45 infected plants • Eradication program implemented • Resistance from some residents • • • • No commercial vineyards in region Greek culinary purposes Public awareness campaign Police escorts for survey teams • Declared successful 2007
  10. 10. Case study: Myrtle rust • Potted nursery plants NSW 2010 • Quickly spread to coastal NSW & Qld • Expected to hit eastern Victoria forests • 1st detection in Victoria at wholesale nursery in Melbourne • Delimitation survey – Suburban parks and gardens – Country towns – Movement of infested nursery stocks
  11. 11. Case study: Oriental fruit moth (OFM) • • • • Endemic introduced pest Known to infest pome & stone fruit overseas Had been “restricted” to stone fruit in Australia Change of orchard pest management – pheromone-mediated mating disruption replaced pesticides • Increased populations in pome fruit not treated for OFM • Mated females move back into nearby stone fruit • Farmers & urban residents cooperated
  12. 12. Case study: Elm leaf beetle • Elms are important landscape trees in urban centres • Avenues of Honour in country towns • Dutch Elm Disease not in Australia but vectors present • Elm leaf beetle (ELB) defoliates elms • Causes tree stress • Susceptibility to disease • ELB hitch hikes on vehicles Avenue of Honour, Bacchus Marsh, contains an elm for each soldier from the local area . (image from http://vegefarmer.blogspot.com.au/) • Spraying difficult, expensive, & has potential side effects
  13. 13. Case study: Elm leaf beetle cont. • Integrated management • Monitoring • Biological control • Safer pesticide application • Complexity of tree ownership • Friends of the Elms Inc. Infested elms adjacent to a busy urban traffic corridor Aggregation of beetles sheltering in a log
  14. 14. Case study: Danger of exotic psyllids Asiatic citrus psyllid Tomato potato psyllid Image: Uni. Nebraska • Sap sucking insects capable of transmitting plant viral and bacterial diseases. • Asiatic citris psyllid (ACP) & Tomato potato psyllid (TPP) are high risk incursions • Both species can infect commercial crops with bacterial disease – ACP: Citrus species – TPP: Solanaceous crops (potatoes, tomatoes, egg plants, capsicums)
  15. 15. Case study: Danger of exotic psyllids • Both species utilise non-commercial host plants – ACP: Murraya paniculata (ornamental), native Citrus species? – TPP: about 40 spp of Solanaceous plants (native & exotic) • Potential entry pathways – Natural wind dispersal (ACP from Papua New Guinea or Timor Leste; TPP from New Zealand) – People (ACP feeds on curry plants and live specimens have been intercepted at the airports – likely that it could establish in an urban or peri-urban backyard first)
  16. 16. Concluding remarks • Peri-urban zone • incursion bridge between urban and rural • complex nature of land uses • Owners do not derive main income from property • Non-commercial farmers not members of industry organisations so difficult to trace • Risk zone for establishment and spread before detection • Informal networks increase risk • Awareness and education critical • Social media can help or hinder • Municipal emergency planning should include biosecurity planning • Biosecurity response success depends on what intelligence is available