For decades, modern agriculture has largely operated on a simple assumption: if weeds become a problem, herbicides will solve it.
And for a long time, they did.
Glyphosate-based herbicides such as Roundup® became deeply embedded in farming systems across much of the world because they were effective, relatively inexpensive, easy to apply, and capable of controlling a wide range of weeds at scale. In many cropping systems, they became not just one tool among many, but the foundation around which weed management itself was built.
But increasingly, even mainstream agricultural researchers are beginning to acknowledge a difficult reality: weeds adapt.
And when an entire farming system becomes heavily dependent on a single herbicide approach, that dependence may eventually start working against the system itself.
A recent New Zealand research programme led by the Foundation for Arable Research (FAR) highlights just how significant this issue is becoming. The four-year project, titled Integrated Weed Management in a World of Herbicide Resistance, is focused on helping growers respond to rising levels of herbicide resistance across New Zealand cropping systems.
The project is not being driven by environmental campaigners or anti-herbicide activists. It is being led by the agricultural sector itself.
And in many ways, that may be what makes the findings so important.
Herbicide Resistance Is Rising Across New Zealand Farms
According to FAR’s earlier herbicide resistance screening programme conducted between 2019 and 2023, resistance is now widespread across multiple farming regions.
South Canterbury reportedly recorded herbicide resistance on 71% of surveyed farms. Mid Canterbury recorded 60%, Southland 59%, and Waikato 61%.
Those are not isolated cases. Those numbers suggest something much larger: a system-wide issue emerging after years of repeated herbicide reliance.
The article notes that ryegrass has become one of the most common resistant weeds affecting cropping farms. Even relatively small numbers of uncontrolled ryegrass plants can significantly reduce yields.
Researchers are also monitoring for glyphosate resistance developing along fence lines and non-crop areas — places where repeated spraying often occurs year after year under similar conditions.
Interestingly, the surveys did not detect glyphosate resistance within the random arable farm sampling itself, although glyphosate resistance has reportedly been identified outside those surveys. That distinction matters because resistance patterns can vary significantly depending on farming systems, weed species, and herbicide use practices.
That detail matters because it reveals something fundamental about resistance itself.
Biology adapts.
The more consistently a single weed-control method is used, the greater the pressure placed on weeds to evolve around it. Over time, the weeds that survive pass those traits on, gradually reducing the effectiveness of the herbicide that once controlled them.
Researchers also suspect regional farming practices may influence resistance levels. Areas where crop rotation options are limited appear to experience higher levels of herbicide resistance, highlighting how simplified farming systems can unintentionally increase long-term vulnerability.
In other words, the success of a herbicide can eventually become part of the mechanism that undermines it.
Why Researchers Are Turning Toward Integrated Weed Management
One of the most striking aspects of the FAR project is the language now being used by researchers themselves.
Rather than advocating continued reliance on herbicides alone, the project repeatedly emphasises concepts such as:
- diversity
- integrated systems
- crop rotation
- crop competition
- non-chemical control methods
- reducing reliance on single solutions
FAR researcher Matilda Gunnarsson explained that growers need to move toward “a more integrated approach, rather than relying solely on herbicides as the main solution.”
That represents a notable shift in thinking.
For years, discussions around reducing herbicide dependence were often framed as unrealistic or anti-farming. Yet increasingly, even agricultural researchers appear to recognise that long-term sustainability may require moving beyond single-tool chemical systems.
Not because herbicides suddenly stopped working entirely.
But because over-reliance itself may be creating new problems.
Why Reliance on Single Herbicides Creates Resistance Problems
This issue extends well beyond glyphosate alone. The deeper problem may be the assumption that any single herbicide system can remain effective indefinitely if used repeatedly across large-scale farming systems.
Nature rarely stays static.
Weeds evolve. Insects evolve. Fungi evolve. Biological systems respond to pressure.
And when farming systems become highly dependent on one dominant control strategy, resistance often becomes less a question of “if” and more a question of “when.”
Historically, this pattern has appeared repeatedly across agriculture:
- insect resistance to pesticides
- fungicide resistance in crop diseases
- antibiotic resistance in livestock systems
- herbicide resistance in weeds
Each time, the response often involves introducing new products, additional chemicals, or more technologically sophisticated management systems.
The FAR project itself references emerging technologies including:
- drones
- camera-guided spraying systems
- digital weed management tools
- inter-row precision spraying
- satellite imagery
None of these technologies are inherently negative. Some may genuinely reduce overall herbicide use or improve targeting precision.
But they also raise a broader question:
Are we moving toward genuinely lower chemical dependence — or simply toward more technologically advanced forms of chemical management?
What Herbicide Resistance Could Mean for Food and Farming
Most public discussions around herbicide resistance focus on farming productivity, crop yields, and economic sustainability.
Those are legitimate concerns.
But consumers may also have reason to pay attention to where this trajectory leads.
If weeds become increasingly resistant to existing herbicides, what happens next?
- More frequent spraying?
- Multiple herbicides used together?
- Stronger replacement chemicals?
- New chemical combinations?
- Greater reliance on precision technologies to maintain control?
These questions become particularly important given that food systems ultimately connect farm practices directly to consumers.
The issue is not simply whether a particular herbicide remains “legal” or “approved.” The larger question may be whether escalating cycles of resistance and chemical adaptation are sustainable in the long term at all.
Even NZ Agriculture Is Beginning to Rethink Herbicide Dependence
One of the most revealing aspects of this story is that the push toward integrated weed management is not coming from outside the farming industry.
It is increasingly coming from within it.
Researchers, growers, and agricultural organisations appear to recognise that dependence on any single herbicide system may eventually become self-defeating.
That does not mean herbicides disappear tomorrow. Nor does it mean farmers are villains. Many growers are operating within systems that evolved over decades around efficiency, economics, and productivity pressures.
But it does suggest a broader transition may already be underway.
A transition from:
- single-solution thinking
toward - diversified system management.
Whether that shift happens gradually or reactively remains to be seen.
Looking Beyond the Next Cycle of Herbicide Resistance
The herbicide resistance issue may ultimately force a larger conversation that extends far beyond weeds themselves.
What does truly sustainable farming look like over the next 20 or 30 years?
Can agriculture continue relying primarily on chemical escalation every time biological systems adapt?
Or does long-term resilience require farming systems that are less chemically dependent from the outset?
These are not simple questions, and there are no easy answers.
Researchers are now seeking further funding to investigate integrated weed management strategies, reflecting a growing recognition that long-term weed control may require more diverse and adaptive farming systems.
But what this latest research project quietly reveals is that even mainstream agricultural science is increasingly acknowledging the limits of relying too heavily on any single herbicide system.
And once that conversation begins, it may become increasingly difficult to ignore where it leads next.
Related Articles
Herbicide resistance is increasingly forcing a broader conversation about how modern farming systems manage weeds, productivity, and long-term sustainability. The articles and resources below explore some of the larger questions surrounding glyphosate-based herbicides, chemical dependence, integrated weed management, and the future direction of food production in New Zealand and beyond.
Beyond the Withdrawal: What Comes (and What Doesn’t) After Glyphosate
As herbicide resistance grows and pressure mounts on existing weed-control systems, what comes next? Exploring replacement chemicals, emerging technologies, and the growing complexity of modern weed management.
Glyphosate vs Roundup: Why This Distinction Matters
Why glyphosate and glyphosate-based herbicides are not always the same thing — and why the distinction matters in public debate and regulation.
Why Glyphosate Isn’t Just a Weed Killer — It’s a Public Health Issue
Examining how glyphosate-based herbicides became embedded across modern food systems and why growing exposure concerns continue to attract attention worldwide.
Rethinking Herbicide Use in New Zealand’s Public Spaces
Why some councils, communities, and researchers are beginning to reconsider long-term dependence on herbicide-based weed control.
Additional Resources
- Foundation for Arable Research (FAR)
- FAR: Arable Extra (issue 132) — Integrated Weed Management [PDF]
- Ministry for Primary Industries — Primary Sector Growth Fund
- Ruralco News — Herbicide Resistant Weeds Widespread, Surveys Show
As herbicide resistance continues to emerge across different farming systems, the conversation may gradually shift from simply finding stronger weedkillers toward rethinking how resilience is built into agriculture itself.
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