PERI-URBAN ENVIRONMENTS AND

WEED INVASION: ISSUES,

CONSEQUENCES AND SOLUTIONS.

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David McLaren1,2, Greg Lefoe1, Tony Dugdale1, Jackie Steel1,

Raelene Kwong1, Charles Grech1, John Weiss1, Fiona Ede1, Franz

Mahr1, Daniel Clements1 and Trevor Hunt1.

1Department of Environment and Primary Industries

2La Trobe University

• Weeds cost Australia $3.5-4.5 Billion annually

• Environmental costs – similar magnitude

• A new weed introduction can threaten

produce exports and cost $millions in control

and eradication costs

• Peri-urban communities are the interface

between urban and rural landscapes

Weed Impacts

Peri-urban weed Issues

• Land speculation

• Land value

• Lack of weed awareness

• Weed management restrictions

• Fire

• Weed sources – purchasing weeds

• Machinery and soil movement

• Animals and fodder movement

The Weed Invasion Curve

PREVENTION

Solution - Weed Risk Assessment

• Majority of weeds – garden plants

• System for declaration of weeds

• Many weed species now voluntarily withdrawn

from sale by the nursery industry or have been

declared noxious.

Arum lily Privets Pampas grass

ERADICATION

Alligator weed – Weed of National

Significance

• Found in peri-urban

gardens being grown as

garden vegetable by Sri

Lancan community.

• Publicity campaign

• Over 800 infestations

treated

• Land ownership/transfer

Solutions

• Brushoff appeared to kill

plants but resulted in

fragmentation - alive

• Mixture of glyphosate and

brushoff was effective.

• Now have successful tools

for eradication.

• Using UAV have been able to

successfully map Alligator

weed infestations.

CONTAINMENT

Containment – Serrated Tussock

• 4 ha in peri-urban suburb

of Broadmeadows in 1954

Containment – Serrated Tussock

• 4 ha in peri-urban suburb

of Broadmeadows in 1954

• 30,000 ha by 1980

Containment – Serrated Tussock

• 4 ha in peri-urban suburb

of Broadmeadows in 1954

• 30,000 ha by 1980

• 130,000 ha by 1996

Victorian Serrated Tussock Working

Party

• Community lead strategy

• Developed in collaboration with DEPI and

facilitated large community serrated tussock

control grants and extension

• Worked in collaboration with Shires and

Councils who implemented rate rebate

schemes for weed management including

serrated tussock.

Solutions – Victorian Serrated Tussock

Working Party

• Comprehensive

enforcement program

• Grazing and pastures

• Herbicides

• Biological control

• Modelling

• Fire risk

• Extension

Workshops

Web sites

Management

guides

Papers

Media

Containment – Serrated Tussock

Working Party

• 45,000 ha now under

long term control

ASSET BASED PROTECTION

Western Grassland Reserve

• Less than 0.5% of

“pristine” basalt

plains grasslands

remain.

• Offset for peri-urban

growth expansion

around Melbourne

Western Grassland Reserve

• Adaptive weed management

• Herbicide impacts on native

species

• Weed eradication trials

• Uses natural enemies of the weed such as

insects, mites or fungi from the weeds

country of origin.

• Sustainable as biological control agents

breed and maintain populations and attack

the weed year after year.

• Every $1 spent on biological control has

returned $23 to the Australian community

Biological Control

Biological control of Gorse

• Gorse is a serious weed in the peri-

urban localities of Wallan and

Kilmore north of Melbourne.

• Community and Government co-

operation

• Equine landcare group – link for

Wallan/Kilmore.

Conclusions

Issues

• Time poor

• Many absentee landowners

• Land fragmentation

Solutions

• Weed Research

• Contractors

• Share farming

• Community engagement and empowerment

• Biological control