Opportunities and challenges for improved management of mobile cropping weeds

The potential for weeds, seeds, and herbicide resistance genes to move across paddock and farm boundaries is well known and an increasing number of costly weeds of cropping are known to be highly mobile. A multidisciplinary study conducted across the Australian cropping zone involving multiple industry partners using spatial weed monitoring with genetic testing, social and economic analyses, and grower-level trialing was used to identify the potential scope for reducing the spread of costly mobile weeds and resistance. The spread of weeds from common sources was confirmed through genetic testing, and spatial herbicide resistance analysis demonstrated that reducing the risk of spread can still have considerable value as substantial susceptibility still remains. Reducing the spread of herbicide resistant weeds was identified as a priority from the grower perspective. The risk of weeds spreading from public land (e.g. roadsides) to their land was the most common source of concern. The demonstrated opportunity for greater attention to management of source weeds on public roadsides is an important result in cropping environments where near-zero in-field weed tolerance by growers (e.g. in fallow) is increasingly the norm. The large potential for greater cross-sector area-wide collaboration and delivery was well recognised and demonstrated by growers, but there was a relatively low level of existing area-wide and collaborative weed management effort. A willingness-to-pay study showed that while 85% of grain growers were willing to invest in additional effort (or practices) to reduce the risk of inter-farm spread of a potentially costly summer weed, there needed to be confidence in a high level of risk reduction. Relative to the more time and administration-heavy approaches of some area-wide weed management schemes, results from these large-scale commercial cropping-based environments point to localised near-neighbour approaches to reducing the impact of mobile weeds as having potential for extensive benefit.

Llewellyn, R., Capon, T., Monjardino, M., Hereward, J., Preston, C., Ratcliff, C., Graham, S., Morgan, T., Quarisa, I., Kirby, R., & Cocks, B. (2024). Opportunities and challenges for improved management of mobile cropping weeds. Proceedings of the 23rd Australasian Weeds Conference Brisbane August 2024. ISBN: 978-0-646-70156-1, 86. https://acrobat.adobe.com/id/urn:aaid:sc:AP:24e14be0-0ebf-450d-8433-5b3c7fd07a45?viewer!megaVerb=group-discover