Herbicide resistance status of grain and cotton cropping regions – strategic insights for RDE

Output 1: By November 2024, assemble a dedicated and structured herbicide resistance survey management team

Team responsibilities include:

• Defining weeds collected and weed seed collection procedures.
• Protocols for estimating weed density and paddock location.
• Identifying and updating herbicides and rate of herbicides screened.
• Central management of the survey and screening data.
• Coordination and dissemination of screening results.

Output 2: By September 2025, deliver to GRDC a clear surveying and screening protocol

Protocol to:

• Utilize and build on the protocols developed in UCS2008-001RTX Determining the incidence of herbicide resistance in Australian grain cropping.
• Identify the necessary sampling intensity to deliver resistance frequency and distribution of data across regions and subregions building from knowledge gained from UCS2008-001RTX. The grain and cotton growing region to be surveyed once during the period of the investment. Surveying to be carried out segmentally each season to achieve adequate coverage for each growing region over the investment timeframe.
• Identify primary target species and provide rationale for testing. It is envisaged the total number of target weeds would not exceed seven per seasonal rainfall region.
• The target weed species and herbicides should be based on clear rational, may be regionally specific, display a value proposition and determined in final consultation with GRDC.
• Identify fields for weed seed collection in consultation with agronomists and growers which meet biosecurity and trespass requirements.
• Secure additional agronomic metadata for paddocks surveyed where possible (e.g. crop type, soil type, spray history, cultural and mechanical control methods etc.).
• Include protocol for estimate of weed frequency, to be estimated simultaneously during the survey of weed species for herbicide resistance.
• Genetic testing of ryegrass populations to determine relatedness includingIcomparison with historical samples where available.
• Standardized protocols to be applied nationally as implemented in UCS2008-001RTX.

Output 3: By July 2028, deliver to GRDC the frequency and resistance status of major winter and summer grain cropping weeds across the Australian grain and cotton growing regions.

• A subjective estimation of weed density to be included.
• Weed frequency to be estimated from data collected during paddock surveys.
• Genetic relatedness of ryegrass populations on roadsides vs in paddock and national diversity.
• Herbicide resistance and any associated paddock metadata to be reported for samples from all areas.
• Herbicide resistance, location and other metadata collected to be shared with AAGI as part of collaboration within the investment, and subsequently hosted on the GRDC national resistance baseline visualization tool. The tool will include resistance incidence on a map interface to a postcode level, allowing growers to access information through an online platform.

Output 4: By July 2024 and annually thereafter, develop and deliver to GRDC a national communication and extension plan to inform industry of the herbicide resistance status of key weeds.

• Yearly plan to include communications and extension to be pursued for the year, ensuring the best options are identified to achieve extension outcomes.
• Plan will include where appropriate; face to face extension, Grower group newsletter/social media, GRDC research updates/conference presentation, Media, Scientific publication, Ground cover articles, video/podcast or webinar.
• Plan will provide a list of extension opportunities/topics for WeedSmart and work in collaboration to achieve at least one extension article a year.
• Extension to include current and historic results.
• Plan will include communication and extension informing growers of the resistance visualization tool when the tool has been completed.

Output 5: By July 2025, deliver to GRDC an estimation of the frequency of major winter and summer grain cropping weeds across the Australian grain growing regions.

• Weed frequency to be estimated simultaneously during the survey of weed species for herbicide resistance.
• A subjective estimation of weed density to be conducted.

Output 6: By July 2027, deliver to GRDC the resistance status of major winter and summer grain cropping weeds to key herbicides across the Australian grain growing regions.

• The Australian grain growing region to be surveyed once during the period of the investment.
• It is envisaged that the total number of target weeds would not exceed seven per seasonal rainfall region. However, the target weed species and herbicides should be based on clear rationale and determined in consultation with GRDC. Weed species may be regionally specific.
• Standard methodology for the survey and the resistance testing to be applied nationally.
• Surveying complies with privacy and biosecurity best practice.
• Results entered into the ""Australian grain herbicide resistance data set" is that which was developed in GRDC investment UCS2008-001RTX.