Weeds and Bushcare News
Watch What Wattle You Grow
September 1, 2005
Media Release from the Cooperative Research Centre for Australian Weed Management
Queensland Silver wattle invading bushland in Warrimoo
Patriotic Australians who like to plant a wattle on National Wattle Day - September 1 - are this year being asked to take special care to plant a local variety.
As well as being beautiful, wattles can be weeds.
When taken out of their native environment to other parts of the continent, some wattle varieties can take over or even wipe out the local native bush as effectively as any introduced plant pest, warns Sandy Lloyd of the Weeds Cooperative Research Centre.
"Wattles are prolific seed producers, so when you take them out of their native range where they are naturally controlled by insects, the seedlings survive very successfully - and they start taking over."
Cootamundra wattle (Acacia baileyana) is unkindly referred to as the "Coota-bloody-mongrel wattle" after it infested large areas of native bushland in its own state of NSW, in Victoria, Western Australia, South Australia and Queensland where it is a declared weed and widely regarded as a foe by bush restoration groups and farmers.
Cootamundra Wattle is a hardy tree which tolerates salt and frost, grows in partial shade to full sun on a range of soil types, and is drought tolerant when established. It invades heathland, woodland, grassland, dry sclerophyll forest and the banks of watercourses. It is moving into intact bushland in several states, displacing local wattles and forming dense stands that shade out other native plants. It also fixes nitrogen in the soil, making it unsuitable for the germination of many native plants.
For more information, go to Cootamundra Wattle page.
The Sydney Golden Wattle (A. longifolia) is another homegrown menace outside its east coast range, and a weed in Victoria, South Australia and Western Australia.
"There are community groups raising money to buy chainsaws to get rid of the Sydney Golden wattles that have infested many areas of WA," says Sandy Lloyd. "That's how bad it has become."
"The problem with wattles is that they tend to colonise areas of native bush, where conservation often relies on the efforts of volunteers - and so are undermining all the effort, care and time that goes into trying to keep the bush in its original state."
Several native wattle varieties are listed as pests in Environmental Weeds: A Field Guide for SE Australia by the Weeds CRC's Kate Blood.They include:
The Golden Wreath Wattle (A. saligna), a weed in NSW, SA and Victoria
The Mountain Cedar Wattle (A. elata), a particularly invasive tree of higher rainfall regions, able to take over undisturbed forest.
Even Australia's national emblem, the Golden Wattle (A. pycnantha) is now reported by scientists to be an environmental weed in some parts of the country.
Many of these weedy wattles are available in nurseries and garden centres, and there is growing concern that conscientious gardeners looking to plant native gardens are unwittingly helping to spread them across the landscape, Sandy says.
"From the garden their huge seed output can be distributed across the local landscape in garden waste, by birds and ants, by earthmoving equipment, in flowing water and contaminated soil," she explains.
"Because of their beautiful flowers, lots of people like to send wattle trees or seeds as gifts to friends and relative both in Australia and overseas - in places like Portugal, South Africa and Chile.
"We know that Acacia dealbata and Acacia mearnsii are now serious invaders in natural areas of the Nilgiris in southern India, for instance.
"I'd really urge people to think twice before they send a wattle as a gift, because despite the kind intentions it could spell the demise of somebody's local ecosystem - or local wattle trees."
Winter flowering Queensland Silver Wattle
Note: Sydney Golden Wattle (Acacia longifolia) and Cedar Wattle (Acacia elata) are not weedy in the Blue Mountains, as they are indigenous to our area. However, the Queensland Silver Wattle (Acacia podalyriifolia) also known as Mt Morgan Wattle, is highly invasive in the Lower Mountains.
Look for Queensland Silver Wattle and other woody bushland invaders on this page.
Sandy Lloyd, Weeds CRC, ph 08 9368 3760
Peter Martin, Weeds CRC, ph 08 8303 6693
or 0429 830 366
World Wide Wattle - visit their website