There is no ‘silver bullet' from the chemical industry to control farmers' biggest enemy, weeds - just ask the man known in agricultural circles as ‘the undeniable global leader in herbicide resistance'.
Winthrop Professor Stephen Powles, who is Director of the Australian Herbicide Resistance Initiative (AHRI) and a member of The University of Western Australia's School of Plant Biology and Institute of Agriculture, was raised on a farm and knows first-hand the destruction wreaked by weeds on farmers' livelihoods. When he was 10, his grandparents lost the war on weeds on their farm and had to sell it.
Yet, seven years ago Professor Powles bought a farm at Quairading, 180km east of Perth, where he is practising what he preaches.
In an article published about his work in Science last week, Professor Powles said Australia's wheat farmers have had the worst weed problem in the world.
His own 648ha property was thick with weeds resistant to several herbicides, and Professor Powles is conducting experiments to find out if the weed ryegrass is able to evolve resistance to his own weed seed management regime.
Since 1983, when Australia's first cases of herbicide resistance were being reported, Professor Powles (who had dropped out of school at 15 but was accepted into an agricultural college and then into the Australian National University) became involved in researching how some ryegrasses could have become immune to the then-popular herbicide Hoegrass.
In 1998 he established the UWA-based AHRI in partnership with the Grains Research and Development Corporation (GRDC). One focus of research by AHRI is on weed seeds, particularly on preventing them from getting into the soil. The latest weapon in this battle is the Harrington Seed Destructor, invented by Darkan farmer Ray Harrington and refined at AHRI.
Farmers who target seeds reduce weeds by up to 98 per cent - but this requires dedication. The best approach is to combine weed-seed capture with herbicides and agronomic approaches such as crop rotation, Professor Powles said.
"You confuse the enemy - it's a bit like guerilla warfare," he said.
Professor Powles will visit the US later this month on a six-week lecture tour to convince farmers there to try his tactics.