[ASC-media] Media alert: Australian Weeds Conference

JCA Media jca.media at starclass.com.au
Tue Sep 19 00:04:27 CEST 2006

Stories from 15th Australian Weeds Conference, Adelaide, 24-28 Sept 2006


19 Sept 2006 

1. Birds spreading Murraya in rainforest

Researchers have found that the popular hedge plant, orange jasmine, or Murraya, widely available from commercial nurseries in Australia, is invading native bushland and rainforest habitats in Queensland with the help of native birds. 

Officially known as Murraya paniculata cv exotica (L.) Jack, it produces fleshy, orange-red fruits favoured by local figbirds. Available from late winter to late spring, the fruits are eaten and the harder seeds eventually deposited when the birds return to the rainforest. Research shows that 75% of the seed remains viable after passing through a bird's gut.
Concerns have been raised that recent large-scale plantings have increased the likelihood that Murraya will become a bird-dispersed environmental weed in subtropical eastern Australia.

A survey of rainforest pockets in the Brisbane area found that all remnants examined had been invaded by Murraya plants. The average density was one plant per 23 square metres, with some up to 1.7 metres high. Researchers say the answer is to encourage gardeners and landscapers not to plant Murraya near remnant rainforest or creekline habitats, and to seek advice on suitable native alternatives from local nurseries. In south east Queensland, native plants suitable as replacement food plants for figbirds include native figs, native palm lilies, the hard quandong and rough leaved elm.

The nursery industry claims there is a cutting-grown variety of available Murraya described as 'non-fruiting'. Researchers would like to undertake controlled studies to verify sterility of the variety before it is promoted widely as an environmentally sound option to the fruiting Murraya often observed in the suburbs of south-east Queensland.

Contact: Dr Gabrielle Vivian-Smith, Qld DNRMW/Weeds CRC - 07-3375 0739, 
mob 0423 025 296
When available: bh Mon-Fri 
Conference attendance:  Yes

2. Weeds killing the goose that lays the golden tourist egg

Kakadu is world famous for its immense flocks of wild magpie geese against tropical sunsets. An important traditional food for Aboriginal people, the magpie goose is an icon of the north and its great flocks a magnet for tourists. 

One of the staple foods for the goose is the native wild rice (Oryza meridionalis). However, scientists have observed for some time that a plant deliberately introduced from South America as a ponded pasture for livestock, known as para grass, readily escapes into the wild. In particular, it invades floodplains and displaces the wild rice, as well as the native water chestnut, driving the magpie geese from their once productive feeding grounds. Floodplains in Kakadu that once resounded to the calls of thousands of the large black and white birds are now silent, carpeted by a dense uniform mat of para grass.

Research presented at the 15th Australian Weeds Conference in Adelaide this week reveals that para grass manages this dominance by shading, preventing the rice seed from reaching the temperature it needs to break its dormancy. Wild rice evolved this mechanism to ensure it germinated as the rainy season approached. 

The result is 100% para grass, no more wild rice and no more geese. One study on the Magela Creek floodplain found that the distribution of para grass increased by some 300 ha in 5 years. The para grass carpet is becoming an increasingly common story right across northern Australia.

Contact: Penny Wurm, Tropical Savannas CRC, Charles Darwin Uni., Darwin 
08-8946 6355
When available: bh Mon-Fri
Conference attendance: Yes

3. Kching! Research into weeds a blue chip investment!

Economics has never played a big part in the science of botany, and that includes the study of all those unwanted weeds. But new research by economists has shown that finding solutions to your humble weed problems hits pay dirt in the long term.

A study in 2003 by the University of New England that revealed weeds costs our primary producers $4 billion every year in costs and lost income. Now a new economic review concluded this year by Sydney company AECgroup has showed how biocontrol, the control of weeds using insects, fungi and other natural organisms, has returned $23 for every dollar invested since this science began in Australia in 1903. On average, every year $4.3m was spent, which led to an annual return of $95.3m.

Now a paper presented at the 15th Australian Weeds Conference by the NSW Dept of Primary Industry examines the case for a new research centre in weeds once the current Weeds CRC winds up in 2008. The study concludes that 'investing $30m of taxpayer funds into a new CRC will leverage a further $63m of in-kind and cash contributions from research providers', the paper says. More importantly, such an investment 'will generate an additional $2,071m in discounted benefits to the Australian economy'.

This means, in effect, that doing high quality research into the nation's weed problems through investment in an Invasive Plants CRC delivers an average benefit-cost ratio of 56:1. It's a long-term return that will benefit our children and grandchildren, their descendants and the environment, and a blue chip investment for the nation.

Contact: Mr Randall Jones, Senior Economist, NSW Dept of Primary Industries 
02-6391 3960
When available: bh Mon-Fri
Conference attendance: Yes

4. Weeds threaten native plants and animals in NSW 

A report presented this week to the Australian Weeds Conference sets out for the first time a detailed account of how invasive weeds are impacting native flora and fauna over a substantial part of the Australian continent. 

Focused on NSW, and prepared by the NSW Dept of Environment and Conservation, the report identified 127 invasive plants adding to pressure on NSW's threatened species. The future of at least half (279) of the state's threatened native plants is now at risk from weeds. The five top invaders are lantana (threatening 96 endangered species), bitou bush (threatening 46), blackberry (threatening 21), kikuyu (16) and Scotch broom (12). 

Scientists point out that two-thirds of the weed species involved are escaped garden plants. These also tend to have the highest impact, threatening 93% of all the at-risk native species. Of these, 36 are still available for sale in NSW, and 56 Australia wide. 

In terms of the number of species involved, the Sydney basin is the state's worst affected area, with the south-west the least affected. There are 1,386 'naturalised' species of alien plants in NSW, these being foreign plants that have made themselves at home and are reproducing. They now make up 21% of the total number of plant species in the state.

Contact: Paul Downey 02-9585 6023	mob 0438 196 663
When available: bh Mon-Fri
Conference attendance:  Yes

5. Biocontrol kicks in against mimosa in the north 

Mimosa pigra L. (mimosa) is one of the worst weeds in Australia. Dense, impenetrable infestations currently cover 800 km2 of floodplains in the Northern Territory. Native plants that used to supply food and shelter cannot grow, and the birds and animals leave or die out. Even Aboriginal people are locked out of country that is important to them.

Since 1979, scientists have found a number of insect species that attack mimosa in its native range in Central and South America, and tested them for Australian conditions. Only insects that feed exclusively on mimosa are considered. So far, 14 have been released in northern Australia, with mixed success. However, such 'biocontrol' measures can take many years to be effective.

In dramatic new results announced this week to the Australian Weeds Conference in Adelaide, the amount of mimosa seed in the soil in infested regions in the NT has shown a massive decline. Soil seedbanks are now around 10% of what they were before biocontrol commenced, a sure sign that the insects are starting to make an impact. For the first time, managers are able to cut back on the amount of follow up treatment required after mimosa has been sprayed. 

Contact: Bronwyn Routley tel. 08-8999 2266    mob 0419 044 994
When available:  19-21 Sept, and pm 22 Sept
Conference attendance:  Yes

6. Ryegrass control increases cereal yields two-fold 

A serious contaminant of cereals, annual ryegrass (Lolium rigidum) is one the most difficult weed issues that modern growers face. With the development of herbicide resistance in ryegrass, farmers desperately need new ways to combat the problem. 

New research in WA presented to the Australian Weeds Conference in Adelaide this week shows that a mix of old and new techniques can come up with a dramatically effective solution. Farmers trialling the method also doubled their cereal yield as a result.

Exploiting the fact that rye grass seeds hang on the stems for longer than many grasses, scientists found that over 75% could be caught at harvest and added to the trash. This was then windrowed and disposed of in various ways. 

The most effective was to burn the windrow, then bury using a conventional mouldboard plough. Seeds buried below 15cm were unable to emerge. The numbers of ryegrass plants emerging after this treatment was only 0.5% of untreated plots. 

Researchers note, however, that the deep furrows left by mouldboard ploughing may themselves cause problems, and further trials on alternative ploughing techniques will be necessary. 

Contact: Sally Peltzer (08) 9892 8504
When available: 24-28 Sept 
Conference attendance:  Yes

Further information

Media unable to reach any of the above sources can contact the Weeds Conference Media Room (Meeting Room 8, 1st floor in the Adelaide Convention Centre) at the Weeds Conference from Monday 25 to Thursday 28 September. The main contact officers will be:

Mr Peter Martin 0429 830 366
Ms Rita Reitano 0419 184 153

Main tel. no. for the Adelaide Convention Centre: 08-8212 4099

Images available 

Images will be available from Tuesday 19 Sept for all the above stories, downloadable from http://www.plevin.com.au/15AWC2006/media.htm.

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