A DECADE of drought has masked the spread of an exotic weed that could devastate Victoria's sheep industry.
Evidence has emerged that roadside slashers have carried billions of Chilean needle grass seeds along vast stretches of the state's 22,400km of freeways and arterial roads.
Now the drought has broken, farmers and DPI staff have seen an explosion in needle grass, about to jump the fence into hundreds of properties lining the Hume, Calder and Hamilton highways.
The sharp Chilean needle grass seeds penetrate sheep skin and flesh, devaluing the animal and posing animal health and welfare problems.
Prominent Victorian landholder Sir Rupert Clarke, of Lancefield, said the roadside needle-grass infestation bordering his property could force him to abandon sheep production unless it was brought under control.
"The spread of needle grass has the potential to make the running of sheep uneconomic," Sir Rupert said.
"We have had experience in Queensland where spear-grass infestation required the termination of sheep grazing and I believe that this is an accepted consequence of the spread of such grasses."
He has already discovered lambs with damaged hides and skin on his property.
"Seeds penetrate the skin and make the production of a saleable carcass impossible," he said.
"The skin is, of course, condemned, resulting in a further loss of between $15 and $20 per head."
Sir Rupert said it was only a matter of time before producers in needle grass-infested areas were penalised in the marketplace.
DPI Chilean needle-grass expert Charles Grech said sheep, kangaroos and farm machinery could easily spread needle-grass seed from roadsides on to farms.
"It (the seed) will stick to anything, four-wheeled motorbikes, your pants," Mr Grech said.
He said roadside slashing was known to spread needle grass to up to 95 per cent of roadsides in outer metropolitan shires.
DPI has developed a slasher-mounted fan to blow seed off the top of slashers to minimise its spread along roadsides.
VicRoads and most council contracts do not contain a clause demanding contractors use fans or even clean slashers.
A VicRoads spokesman said its annual state-wide weed management budget was about $2.5 million.
"These funds deliver the state's weed control program across the arterial road network," the spokesman said.
