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Legislative Council - Fifty-First Parliament, Second Session (51-2)
2008-04-02 Daily Xml
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SLEEPER WEEDS

The Hon. SANDRA KANCK (15:55): In a home garden, what might be a weed to me could well be a beautiful plant to someone else. However, there are weeds that are definitely weeds because they are classified as such, yet people continue to grow them in their home gardens. But often they escape, and what looks beautiful in a backyard can become a scourge in areas of native flora.

Just look at what was once seen as a very pretty plant, the bridal creeper, and its impact when it escaped from suburban gardens: it took over parts of Fleurieu and Eyre peninsulas and completely smothered and therefore destroyed many native plants at ground level. That is an example of what can happen when mere weeds transform into invasive species. Fortunately, biological control methods have been implemented against the bridal creeper on Kangaroo Island and Eyre Peninsula, and it is having effect.

Boneseed, with its deep green leaves and its bright yellow flowers, was brought from South Africa in the late 19th century, but it is now a proclaimed weed in South Australia because of its hardiness and its propensity to take over native bushland. It is important to note that one plant can produce 50,000 seeds, with the impact that that will have on native birds and animals.

The Weeds Management Society of South Australia tells me that biological control methods to control invasive species yields a 23 to one return on the research investment, and they work particularly well in areas where spraying, for instance, might not be practical, such as steep, rocky or arid areas.

The cost of weeds to Australia in terms of cropping, pastoral and native ecosystems is $4 billion per year. We have used pesticides to such an extent that in almost all farms in South Australia there is a problem of herbicide-resistant weeds, and that is a problem that will lead to a loss of land for agricultural production. We need much more action to deal with this problem of weeds. Victoria is spending $20 million per annum on weed research and control; but, by comparison, South Australia spends just $2 million.

Victoria has a program where bushwalkers are trained to be able to identify and remove weeds, so why do we not have something similar? Bushwalkers are an unused resource because these people are already placing a high value on the environment. Why do we not have a weed spotters network similar to Victoria?

What role is the Department for Environment and Heritage playing in educating nursery owners and operators about the potential for some of the plants they sell to go feral? I wonder how many nurseries are selling plants which, although not classed as invasive species, have the potential to become so. These are called sleeper weeds.

I have, for instance, recently seen lantana for sale in a nursery, and this is a plant that has taken over parts of the national parks on the east coast of Australia and, with the right set of circumstances, it could do the same here. I wonder why fountain grass is still being sold in South Australian nurseries. The yellow star thistle is present in South Australia, which is worrying because we have the same climate as California and Argentina, where it has become an invasive species.

A minor change in a plant's genetics or a change in climate can trigger growth in the population of a sleeper weed. Mimosa has become a seriously invasive weed in the Northern Territory, yet it sat around quietly for 70 years without doing damage. Australia has somewhere between 28,000 and 32,000 introduced plant species, and who knows when one of them could become first a weed and then an invasive species.

The Co-Operative Research Centre for Weed Management has been based in Adelaide for 14 years, and the state government has sat back and relied on it to do the work the government ought to be doing. However, South Australia should not expect that the benefit of this centre will continue unless we lobby to keep it here. Its existence is not guaranteed beyond June of this year and, even if the federal government decides to keep it, there is no guarantee that its location will continue in Adelaide.

Should it move, no doubt it will become eastern states focused. Research into weeds is vital to the natural environment, agriculture and the state's economy and, as the Weeds Management Society says, prevention is better than cure.

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