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Weeds researchers work together to cut red tape 29 Jul 2013

An Australian researcher is hoping to introduce a natural enemy of a weed invading parts of Lord Howe Island to help restore the pristine environment of this World Heritage area.

The search for a solution to control crofton weed (Ageratina adenophora) has seen scientists from Australia, South Africa and Mexico working together to find the best control agent, and to import it in quarantine to Australia in record time.

“Given many of the weeds in these countries originate in Europe, especially the Mediterranean, South Africa and Central and South America, so too do their natural enemies,” said CSIRO researcher Louise Morin.

Dr Morin has just completed testing the potential biocontrol agent for crofton weed, Mexican rust fungus (Baeodromus eupatorii).

Initial support for the project came from the Lord Howe Island Board, with funding from the National Weeds and Productivity Research Program managed by the Rural Industries Research and Development Corporation.

“Our testing showed the fungus is safe to release because it didn’t infect the 60 related species to crofton weed, except for two other introduced Ageratina species, that are already weeds in Australia,” said Dr Morin, who has recently sought permission to release the rust in Australia.

It was thanks to the work already conducted by her international colleagues that this natural enemy is likely to be released so quickly.

“The process of finding and testing a natural enemy for a weed can take many years, and I only had funding for just 12 months,” she said.

Thankfully Dr Morin was able to piggy back on the work of South African biocontrol researchers who were already geared up to undertake a survey of potential insect control agents for crofton weed in Mexico, where it originated.

“We were interested in the rust fungus that had been found in previous surveys by the South Africans and asked them to extend their survey to also collect the fungus,” she said.

“The collaboration saved me a lot of red tape and time. The South Africans also had an existing arrangement with the Mexicans so were able to access export permits for the natural enemies.”

Dr Morin intends to share the results of the testing with the South Africans so that they too can benefit of the collaboration if they decide to consider the rust as a potential control agent for their country.

“With these results in hand, they would only have to perform limited additional testing to demonstrate that it is safe for introduction in South Africa.”

Dr Morin said Australian biocontrol researchers also have a close relationship with staff from the United States Department of Agriculture (USDA), which funds CSIRO researchers in Brisbane to carry out biocontrol studies on Australian plant species that are weeds in the USA.

Meanwhile Lord Howe Islanders are looking forward to the release of the rust fungus to attack the crofton weed that is threatening native fern and herb communities.

The local community puts a high value on maintaining the Island’s beautiful environment and the Lord Howe Island Board has been eradicating weeds from the island since 2004.

Mainly found in inaccessible areas, crofton weed has proven impossible to control as options like herbicide and cultivation are not practical.

Once permission is granted, the rust fungus will be released on mainland NSW where the weed is mainly a problem in coastal areas.

The initial damage on crofton weed will be assessed before approval is sought from the Lord Howe Island Board for release on the island.

Dr Morin has already experienced success in the use of biocontrol for another environmental weed, mistflower (Ageratina riparia), that invades rainforests in eastern Australia.

She’s also seen dramatic results from earlier work to control bridal creeper (Asparagus asparagoides), a serious weed that was dominating and smothering understory vegetation in natural habitats and citrus growing areas of Australia.

However, she says it’s becoming more difficult to bring new biocontrol agents to Australia because of lack of funding.

“Biocontrol research takes time,” says Dr Morin. “First we have to find the potential agents that are closely suited to the weeds of interest. Then we need to do extensive testing to make absolutely sure they don’t attack other plants.

“Nonetheless, these days, the process has been made faster because we can use specific DNA genotyping to assess the natural diversity of the weed, and where we are likely to find pests against it,” she said.

“While we can cut the time this takes by working closely with our international colleagues, this work may require funding for periods as long as 10-15 years, rather than the year to year funding that we are forced to contend with,” she said.