The potential to target and destroy weed seeds when harvesting irrigated crops like rice, will be outlined by Graham Centre researcher Dr John Broster at an international symposium next week.

Dr Broster from the School of Agricultural and Wine Sciences at Charles Sturt University (CSU) in Wagga Wagga will present a paper at the Global Herbicide Resistance Challenge in Denver in the United States on Thursday 18 May.

"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 seedbank.

"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.

"In Australia there are a limited number of rice herbicides available therefore there is an opportunity to be proactive and maintain or increase their life-span," Dr Broster said.

"In many dry-land grain regions of Australia farmers have been forced to adopt HWSC as there are no or minimal herbicides left due to resistance."

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," Dr Broster said. "The screening for herbicide resistance of these samples will soon to commence in the research glasshouses."

CSU also operates a commercial herbicide resistance testing service, screening specific weed populations for producers.

"The aim is to provide information to producers about herbicide resistant weeds in their area to help them avoid using herbicides that are no longer effective. It also provides valuable information about the incidence of herbicide resistance," Dr Broster said.