Australian scientists found that an innovative new approach to sugar cane plantation weed management trialed in select Great Barrier Reef (GBR) catchments have shown a dramatic 90 percent reduction in runoff of highly soluble herbicides into waterways, a latest research statement of CSIRO, Australian national science body, showed on Tuesday.

The results of the study have been published in the international journal Science of the Total Environment. It is supported by the Australian federal government through Reef Rescue Research and Development funding from Caring for Our Country Initiative. The Reef Rescue program is a five-year, 200-million-AU dollars (almost 189.3 million US dollars) investment by the Australian government.

According to the statement, scientists from CSIRO's Water for a Healthy Country Flagship trialled a new technique for applying herbicides to raise beds of furrow-irrigated sugar cane by using a specially adapted shielded sprayer.

The technique minimizes the likelihood of PSII herbicides such as diuron, atrazine, ametryn and hexazinone coming into contact with irrigation water, the statement said.

Many of the herbicides used in the region are PSII herbicides that are known to negatively impact reef ecosystems. These waters discharge into the internationally recognized Great Barrier Reef ( GBR) World Heritage Area and subsequently into the Great Barrier Reef Marine Park. Improved farming techniques such as the shielded sprayer help keep herbicides on-farm have potential to have a significant and positive impact on water quality in the GBR.

According to CSIRO research leader Dr. Rai Kookana, the conventional application of herbicides in furrow-irrigated sugar cane production is to broadcast spray across the whole field using boom sprayers, which applies herbicides to both beds and furrows.

"Irrigation water then carries the herbicides with the tail water into the drainage channels, into nearby creeks and rivers and potentially into the GBR lagoon", said Dr. Rai.

Jon Brodie of James Cook University confirmed that "the amount of some herbicides in creek and estuarine waters during this period regularly exceeds Australian water quality guidelines and could potentially affect, for example, coastal sea grass."

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