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

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. What am I talking about?
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Definitions of per-urban
Implications for biosecurity
Some case studies
Concluding remarks

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?

6. 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

7. 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

8. Biosecurity 2
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Border protection
Containment & eradication
Pest infested zones
Areas of low pest prevalence
Pest free areas of production
Pest exclusion zones
Pest risk zones

9. 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

10. 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

11. Case study: grapevine leaf rust
• Private garden grapevine Darwin 2001
• Surveys within 15kms found 45 infected
plants
• Eradication program implemented
• Resistance from some residents
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No commercial vineyards in region
Greek culinary purposes
Public awareness campaign
Police escorts for survey teams
• Declared successful 2007

12. 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

13. Case study: Oriental fruit moth (OFM)
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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

14. 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

15. 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

16. Case study: Danger of exotic psyllids
Asiatic citrus psyllid
Tomato potato psyllid Image: Uni. Nebraska
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Sap sucking insects capable of transmitting plant viral and bacterial
diseases.
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Asiatic citris psyllid (ACP) & Tomato potato psyllid (TPP) are high risk
incursions
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Both species can infect commercial crops with bacterial disease
– ACP: Citrus species
– TPP: Solanaceous crops (potatoes, tomatoes, egg plants,
capsicums)

17. Case study: Danger of exotic psyllids
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Both species utilise non-commercial host plants
– ACP: Murraya paniculata (ornamental), native Citrus species?
– TPP: about 40 spp of Solanaceous plants (native & exotic)
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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)

18. 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