Never great hosts of Western Australia’s Eagles or Dockers, South Australia (SA) has now turned its venom on a common threat that could shut the door on half of Australia’s wheat markets and cripple canola yields.

The parasitic plant, branched broomrape, first appeared in a beachside Adelaide suburb almost a century ago before being reported in SA’s agricultural region 70 years later. The Grains Research & Development Corporation (GRDC) has funded efforts to cordon off infested areas and eliminate the pest, which can slash yield by 75 per cent when it attacks a canola plant.

Branched broomrape attaches itself to the roots of donors and syphons off valuable nutrients for itself. It is so attuned to this pattern that its seeds can lie dormant for up to 15 years before detecting the presence of host plants and sending interceptor roots to raid their nutrient stocks.

While the pest’s native relatives pose no threat to commercial crops, branched broomrape’s presence precludes the sale of grains to several international markets. Buyer reluctance to import the pest with grain shipments is driven by its dust like seeds, which can spread rapidly via machinery, animal fibres and wind.

But while these characteristics suggest a pessimistic outlook for control of the weed in Australia, the GRDC has supported an ambitious project to eradicate the pest. Led by John Matthews of Adelaide University, the research tested herbicide treatments to identify best management practices and is experimenting with novel technologies to destroy seed banks.

The weed’s spread has waned in recent years and although Dr Matthews believes the quarantine zone may extend beyond its current 160,000 hectares before retreating, he is confident the tide will turn.

Supported by growers and the Federal Government, the team’s program of DNA probes, global positioning system tracking and bi-annual field checks of about 8000 quarantine paddocks has informed a comprehensive database on where the weed is growing, or hiding in the bank.

Using farming systems devised by the project, which largely centre around Group B herbicide applications and non-herbicide treatments such as experimental microwave technology and soil drenches to infiltrate and kill seed bank reserves, Dr Matthews aims to scale back quarantine restrictions during the next decade.