MORE herbicide resistant weeds are being found on public land in the first-ever roadside weed survey released recently.The study found weeds resistant to the popular chemical herbicide, glyphosate were far wider spread than agriculture land.
Fifty per cent of roadside weeds tested in Western Australia and Queensland in the research were found to be resistant.
The research said weed management on public land was contributing to the risk of resistance, because of ignorance of the problem and alternative herbicides.
It presents a huge potential problem for Australia's public land managers, mainly state and local government, with 612,000km of roads considered at risk.
"Non-agriculture sectors where glyphosate is used exclusively for weed management have a high risk of glyphosate-resistant weeds evolving," lead researcher Christopher Preston said.
"Weed management practices other than glyphosate need to be adopted to reduce this risk."
Dr Preston's research found 136 glyphosate resistant populations of annual ryegrass and fleabane along roadsides from Queensland to Western Australia.
This was approximately 50 per cent of all populations tested during the roadside weed survey.
Dr Preston, who also chairs the Australian Glyphosate Sustainability Working Group, said alternative practices need to be used to manage the risk on public lands.
"Nearly 60 per cent of interviewees were in the poor to moderate categories regarding their level of understanding of herbicide resistance and its development," Dr Preston said.
"Management risks were particularly high for water authorities, railways, aviation areas and local government.
"Private contractors and consultants and transport authorities for example, Main Roads nominated the lowest risk strategies on average."
Dr Preston said a concern was the lack of formal record keeping on herbicide effectiveness and monitoring which could delay the detection of resistance.
He said managing authorities were challenged by budgets which had not kept pace with inflation over the last decade, and high turnover of staff had resulted in a loss of knowledge of weed control.
He recommended the development of training programs for authority staff, and the rotation of a wider range of herbicides and weed control methods.