Both dryland and irrigated agriculture in the Riverina suffer from the issue. 

But new research from a herbicide resistance authority in Wagga provides promising outcomes in tackling the problem.

It is so promising that Graham Centre researcher Dr John Broster will present his findings at the Global Herbicide Resistance Challenge in Denver, US. He will outline ways to target and destroy weed seeds when harvesting rice. 

Dr Broster from the School of Agricultural and Wine Sciences at Charles Sturt University (CSU) says some of the techniques had been successfully been used in broad acre dryland operations in Western Australia. 

“Herbicide resistant weeds are a major impediment to Australian grain production including rice and one of the newer methods used to reduce their impact is the collection and destruction of weed seeds at harvest,” Dr Broster said.

“Harvest Weed Seed Control (HWSC) systems including narrow windrow burning, chaff lining, chaff tramlining, chaff carts, bale direct system and the Harrington seed destructor (HSD) can help reduce the seed bank,” he said. 

“The lay-out of irrigation bays and flood water do create challenges for using some of these methods. “We also need to know more about weed seed retention, and where the weed seeds finish, that is whether they end up in the grain, chaff or straw fractions, to help optimise control systems.”

Dr Broster said rather than a stand-alone system, harvest weed seed control should be part of a suite of management practices including herbicides and hygiene of machinery and banks. Dr Broster manages CSU’s herbicide resistance research conducting random paddock surveys to determine the level of herbicide resistance to commonly used herbicides.

Last season 520 paddocks were visited across the NSW grain growing region collecting weed seeds from winter crops, summer dryland crops and rice crops. 

“The screening for herbicide resistance of these samples will soon to commence in the research glasshouses.”