[ASC-media] Media release: Of 15000 infested footy fields and the family car

JCA Media jca.media at starclass.com.au
Thu Sep 28 10:21:07 CEST 2006

 15th Australian Weeds Conference Media Release
24-28 Sept 2006, Adelaide Convention Centre

28 Sept 2006


In a breakthrough presented this week at the 15th Australian Weeds Conference in Adelaide, scientists reported the first major success against a Central American weed that has spread over 150,000 ha of a WA cattle station. The core infestation alone is 45,000 ha, equivalent to 15,500 football grounds. As well as dense thorny thickets that make mustering both difficult and dangerous, land in the core infestation now carries less than half the original stock numbers.

Descended from just two trees planted at Mardie Station early last century, the mesquite pods were deliberately thrown from horseback and vehicles for some years during mustering season to provide shade around mills and watering points. However, by the 1950s it was clear the thorny tree was spreading out of control, and the station began trying to contain it. But after 30 years of trying and many thousands of dollars, the invasion appeared unstoppable.

However, scientists from CSIRO and the WA Dept of Agriculture and Food have at last scored a win in the long battle with the leaf-tying moth Evippe, introduced in 1998 from the tree's native range as a 'biocontrol agent'. Now abundant in the release area, the moth stresses the mesquite trees by causing defoliation. Growth rates have been slashed by 80%, and seed set has fallen dramatically. 

This technique, in combination with other clearing and chemical techniques, now offers pastoralists their first hope in the fight to bring mesquite under control.

Scientists point out that the low productivity of the rangelands means that the technique of biocontrol is normally the only economically viable weed control tool available in such country.

Contact: Ms Linda Anderson, Pilbara Mesquite Management Committee, Kurratha 08-9144 1844, 0407 139 302 

Weeds spread by the family car

Many farmers and grader drivers are aware how effective their vehicles are at spreading weeds, and some authorities now require a vehicle wash down as a standard practice when leaving weed-infested areas.

However, in a project reported this week at the 15th Australian Weeds Conference in Adelaide, the family car was nailed as the number one culprit. 

In a survey conducted in Victoria, over 70 passenger vehicles were checked for weed seeds. Vic DPI Weed officer at Horsham, Michael Moerkerk, discovered that 29 of the vehicles examined were carrying noxious weed seeds. One 4WD wagon was carrying the seeds from 53 different plant species, many more than the machinery inspected. 

Although only 10% of the species hitchhiking in this way were declared noxious weeds, 41% of all passenger cars contained seeds from declared weeds.

And much to the surprise of researchers, and no doubt to authorities that require careful wash down of their vehicles, the noxious stowaways were more often in the passenger cabin than underneath the car. These seeds were most likely brought in on clothing, footwear and equipment. The second most popular place for seeds to hide was in the engine housing.

'The message is that when we visit areas infested by invasive plants', says Mr Moerkerk, 'we need to do a simple check of our gear and clothing before we climb back in the cabin.'

'Shoe laces are a great free ride for weed seeds. But when you find them later and pick them out don't just throw the seeds away where you stand', says Mr Moerkerk.
'We need to think about what we are doing, and dispose of seeds effectively so they can't germinate', he says. 'It's a simple mindset we can all easily adopt - and teach children too'.

The study also revealed which species were most the common hitchhikers. The top five were vulpia (silver grass), lolium (rye grass), eucalypts, juncus and phalaris. 

Similar surveys in Canberra in the 1970s found 259 different plant types being dispersed by vehicles.

Contact: Mr Michael Moerkerk, Vic. Dept of Primary Industries, 0419 361 736

Further information

Mr Peter Martin 0429 830 366 

These and other stories are available on the Conference media pages at: www.plevin.com.au/15AWC2006/media.htm. 

Images of mesquite are available from the Weeds CRC, tel. 08-8303 6590

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