VegNET NSW: Future-proofing vegetable production by upskilling growers
9 December 2025
VegNET SA: South Australian growers connecting, learning, and bringing new ideas home
9 December 2025
Tasmania’s north-west region hosts some of Australia’s most diverse and intensive vegetable production systems. Short crop rotations and a mix of vegetables, potatoes, poppies, pyrethrum, grains and pasture are commonly contracted to different processors or packers. Each contracting company advises on crop management and growers are supported by their commercial agronomists. The management on a crop by crop rather than a farming system basis has led to complex weed management challenges, including herbicide resistance. To address these challenges, VegNET Tasmania’s third annual cross–industry weeds forum, which was held at the Paranaple Convention Centre in Devonport on 3 July 2025, brought together advisors, growers, researchers, processing/packing company representatives and service providers to explore practical, collaborative approaches to integrated weed and herbicide resistance management across these dynamic systems.
Understanding the production system
Tasmania’s north-west region supports some of the most intensive and diverse vegetable production systems in Australia. Key crops include potatoes, onions, carrots, brassicas, peas, beans along with poppies, pyrethrum, and cereals. There are periods of cover crop, short term pasture or fallow phases. Rotations are typically planned one to three years ahead, however, are regularly adapted in response to annual contracts from local packers and processors which may change based on seasonal market demand. Major vegetable packers, processors, and extraction crop industries often play a role in agronomic decisions alongside growers’ independent or more often commercial agronomists. Advice given usually aims at the crop currently grown, not the rotation. Spray contractors are used on many farms. This means that the best timing or conditions for weed control may be missed during busy times. Above mentioned factors are creating a production landscape that is both dynamic and complex for managing weeds across multiple crops and diverse rotations.
Collaboration across industries
Collaboration remains a key focus of the Forum, recognising that many of Tasmania’s weed challenges are shared across industries. For many attendees, it was one of the few opportunities to come together each year and discuss weed management openly across sectors. Forum feedback from the past three years highlighted that VegNET’s initiative to bring the event together each year helps to build a shared understanding and supports more consistent, effective approaches to managing weeds across Tasmania’s diverse production systems.
This sense of collaboration was evident throughout the entirety of the forum. Discussions moved from the problem at hand to, what’s next for Tasmanian growers, advisors and industry stakeholders in tackling resistance and planning future rotations.
Building understanding through root cause analysis
The 2025 cross-industry weeds forum opened with Tim Groom, Managing Director of Wynyon Pty Ltd, a Tasmanian onion exporter. Tim drew on his extensive experience in onion production, recent herbicide trials and research to guide participants through a root cause analysis exercise. The focus was on root causes of herbicides resistance in ryegrass. Borrowing from lean management approaches, Tim encouraged attendees to first define the problem and then strip it back to its underlying causes, to get to the root cause.
Attendees from mixed industries, mapped out factors contributing to weed control failures for ryegrass, which has become a major issue in Tasmania. Examples included:
- Ryegrass going to seed and spreading between farms
- Farm hygiene issues, such as lack of machinery wash-downs spreading seed
- Long growing seasons giving time for grass to germinate, leading to late flushes close to crop harvest
- Timing of Group 1 herbicide application in cold conditions leading to reduced efficacy
- Reliance on the same herbicide groups across multiple crops
- Lack of communication throughout rotation between different stakeholders managing the crop / paddocks.
The discussion highlighted the complex mix of factors influencing weed control in Tasmania’s diverse production systems. Participants agreed that ryegrass resistance to Group 1 herbicides is a growing concern and that management decisions are often shaped by seasonal conditions, rotations, and market pressures. The session helped identify where practical adjustments — such as timing, product choice, and hygiene practices — can strengthen outcomes across different crops.
Getting the most out of pre–emergent herbicides
Following morning tea, Dr Chris Preston from the University of Adelaide delivered a detailed session on the role of pre-emergent herbicides within broader weed management strategies. With more than three decades of research in the grains industry, Preston emphasised that successful weed control depends on taking every possible opportunity to manage weeds across the entire crop rotation — not just in the current crop e.g. onions and season.
He encouraged growers to think about each crop as a chance to drive weed numbers down, even if it means making difficult decisions about which crops to grow. Grain growers, he noted, have often had to adjust rotations or temporarily step away from preferred crops to regain control of problem weeds.
In Tasmanian production systems, this is often a challenge with vegetable growers reliant on back–to–back crops with limited cropping area to include break crops over multiple seasons.
Preston shared insights from long–term trials across the grains sector, showing that ryegrass seedbanks can be driven down by ‘stacking tactics’ across different crops. For example, they had success with a double pre-emergent strategy using different actives that delivered up to five months of ryegrass control in wheat and created opportunities for better management in break crops.
He cautioned that clethodim, a group 1 herbicide, still widely relied on, is most effective on young ryegrass when paired with quality surfactants and oils. Off-label high rates, though sometimes tempting, pose risks to both crops and stewardship. Chris urged growers to recognise that resistant weeds will always evolve – the goal must be reducing populations so that resistance matters less.
The discussion also turned to new technologies and chemistries, with potential future roles for robotic and laser weeders, new modes of action under trial, and a reminder that innovation often comes with higher costs. The key message: invest where returns and avoiding losses due to weeds justify it and use every opportunity in the rotation to tackle ryegrass.
Collaborative crop rotation exercises
A highlight of the forum was the interactive group exercise, where two growers in the room presented their current crop rotation and attendees then worked in cross-industry groups to plan weed management strategies for this rotation. Each group, guided by the VegNET team, mapped out the rotations and strategies by using sticky notes and markers, exploring different combinations of cultural, physical and chemical controls. Each group then reported back, explaining the why behind their approaches.
Across the groups, several common themes emerged:
- Stacking effective years: Several participants suggested deliberately stacking two strong grass control years in sequence — often using competitive crops like wheat or potatoes — to help drive down the ryegrass seedbank before moving back into crops where it may be more difficult to control grass
- Limited chemical control options in common rotational crops: Poppies, pyrethrum, onions and peas were consistently identified as the hardest crops for grass management, with limited in crop herbicide options and multiple Group 1 applications across short rotations
- Herbicide resistance: Many rotations included repeated use of Group 1 herbicides, highlighting the pressure on existing chemistry and the need to plan rotations that allow different modes of action. The challenge is managing resistant weeds in rotational crops where is it possible to reduce the seedbank
- Cultural control opportunities: Groups discussed options such as introducing short pasture or grazing phases, sowing multi-species cover crops, and using cultivation or stale seedbed techniques in cereals and potatoes to reduce ryegrass numbers
- Practical constraints: Contracts and short rotation cycles were recognised as limiting factors, often leaving growers little flexibility to change crop sequences even when weed pressure is high
- Paddock history: With growers working with multiple packers and processors and the inclusion of extraction crops in common rotations, often the paddock history or sharing of information between organisations is limited to help with ongoing management plans.
The exercise effectively reinforced a key takeaway for the group: thinking strategically, paddock by paddock, and planning for the whole rotation and farm — not just the next crop — can make a real difference in managing weeds. If the cost of yield and quality loss resulting from herbicide resistance is greater than the cost of implementing new strategies, investing in alternative management strategies may provide a favourable outcome.
Looking ahead
Key take-outs from the Forum centred on the value of continued collaboration, access to practical information, and the need to keep adapting management as new challenges and research emerge. The day reinforced the importance of bringing industry together to share experiences and explore realistic, region-specific weed management options.
VegNET Tasmania will continue to build on these outcomes by developing new resources and keeping growers, advisors, and researchers connected. The cross-industry weeds Forum will return in 2026, providing another opportunity for the industry to come together and track progress.
There has also been recent investment by local vegetable production companies in the Ecorobotix ARA precision sprayer, reflecting Tasmania’s growing interest in technologies that improve the precision and efficiency of chemical applications. These innovations, alongside new research and VegNET Tasmania extension activities, will continue to shape how growers approach weed control in the years ahead.
In the coming months, growers will also be able to engage with the Accelerating adoption of Area Wide Integrated Crop Management in vegetable, onion and potato growing regions project (MT24012) — a national Hort Innovation levy funded investment aimed at supporting practical adoption of integrated pest, disease, and weed management. Details about the project can be found on the AUSVEG website.
Weed management will remain a continuing challenge for Tasmanian growers, but ongoing collaboration, new research, and practical innovation will be key to keeping ahead of it. By staying connected and applying integrated approaches across rotations, Tasmanian growers are well placed to keep building resilient and profitable vegetable production systems.