When Spray Doesn’t Stay Where It’s Sprayed
We like to think of chemical sprays as precise—a targeted solution, applied with care, doing its job and then disappearing. But glyphosate doesn’t work that way, not always. Once released, it doesn’t just kill weeds. It drifts. It lingers. And sometimes, it lands where it was never meant to go.
This phenomenon, known as spray drift, is one of the most under-discussed public health risks associated with glyphosate use in New Zealand.
What Is Spray Drift?
Spray drift occurs when herbicides like glyphosate are carried by wind or air currents beyond their intended target. It can happen during application — especially when sprayed in windy or dry conditions — or even later, as vapors or droplets move with changing temperatures.
And it doesn’t take much. Even small-scale drift can result in measurable exposure to people, animals, waterways, and crops. The further glyphosate travels from its application site, the more likely it is that someone else is absorbing the consequences.
Where This Happens in New Zealand
Spray drift isn’t just an agricultural problem. It’s a community issue. Here’s where it’s happening close to home:
- On school boundaries, where council contractors spray grass verges and fence lines.
- Around parks and sports fields, often while families are still nearby.
- Along residential streets and berms, with no signage, no warning, and no consent.
- Near early childhood centres, where little lungs are especially vulnerable.
Many residents report noticing a strong chemical smell near their homes or schools — only to later discover that a contractor had sprayed that morning. No notice. No chance to stay inside. No say.
What’s the Risk?
While New Zealand agencies often dismiss these concerns by saying glyphosate is “low toxicity,” that statement ignores several important realities:
- Exposure routes matter. Inhalation, skin contact, and ingestion are all possible through drift.
- Children are more vulnerable. Their smaller body size and developing systems make them less able to detoxify chemicals.
- No level of drift is tested for cumulative impact. Especially not when people are exposed repeatedly, across multiple locations — home, school, sports grounds, and food.
Spray drift isn’t theoretical. A study published in Environmental Pollution investigated pesticide residues in soil from organic and conventional farms across the European Union.
The study found that organic farms had up to 90% fewer pesticide residues than conventional farms, but contamination was still present, indicating that pesticides can drift from conventional to organic farms. This highlights the potential for glyphosate to affect areas beyond its intended application, raising concerns about its reach in our communities. So how far does it travel in your neighborhood? And who’s measuring?
Consent Matters
If someone sprayed an unknown chemical near your children’s play area without telling you, would you be okay with that?
Because that’s what’s happening across New Zealand — in both rural and urban areas. Not only is there no consent, there’s often no notification. And when residents raise concerns, they’re told not to worry — that the levels are safe.
But safe by whose standards? And safe for whom?
We Need a National Conversation
Glyphosate use is still legal — for now. But even within that reality, the issue of uncontrolled drift into public spaces deserves urgent attention.
- Why isn’t signage required for all public spraying?
- Why aren’t councils held accountable for drift exposure around schools and playgrounds?
- Why are we still accepting the idea that if it’s “legal,” it’s automatically “safe”?
Spray drift highlights a deeper problem: a regulatory system that protects products more than people.
Spray drift doesn’t just impact people. It’s been shown to harm native trees and forest systems as well. A 2024 feature from Yale Environment 360 highlights how herbicide drift and repeated applications are weakening natural ecosystems, killing non-target trees, and changing the dynamics of entire landscapes. If trees can’t withstand the collateral damage, what hope do we have for vulnerable communities?
A Final Thought
You shouldn’t have to wonder what your children inhaled at school today. Or why your dog is licking the grass and foaming at the mouth. Or why your veggie garden — nowhere near a field — tested positive for glyphosate.
This is bigger than weeds. It’s about informed consent. Transparent practices. And a right to live in a community where chemicals don’t cross fences — or boundaries — without warning.
We need to stop treating spray drift like a side issue.
Because when it lands where it doesn’t belong, so do the consequences.
Resources & References
Spray drift may be invisible, but the research is mounting. These studies and official resources highlight how herbicides like glyphosate don’t always stay where they’re sprayed — and how that can affect not just weeds, but people, pollinators, and entire ecosystems. The more we know, the harder it is to keep looking the other way.
Glyphosate Drift from Railway Herbicide Trains (2024)
A Swedish field study investigated glyphosate drift from herbicide-spraying trains along railway lines. Drift levels decreased sharply with distance—dropping from 1800 g a.e./ha at the application site to 5 g/ha within 1 meter. Beyond 1.5 meters, the impact on non-target vegetation was minimal, and glyphosate concentrations in nearby ditches remained below environmental quality standards.
https://www.sciencedirect.com/science/article/pii/S0048969724073650
Biological Impact on Corn from Aerial Glyphosate Drift (2010)
This U.S. study assessed corn injury from aerial glyphosate applications. Significant damage, including plant death, was observed up to 6 meters downwind, with measurable effects on chlorophyll content and plant growth extending to 25 meters. These findings underscore the potential for substantial crop injury even at moderate distances from the application site.
https://www.ars.usda.gov/ARSUserFiles/60663500/Publications/Reddy/Reddy%20et%20al%20PMS10%2066-1148-1154.pdf
Impact on Plant Flowering in Agro-Ecosystems (2021)
Research demonstrated that glyphosate drift adversely affects flowering in non-target plants within agro-ecosystems. Such impacts can disrupt pollination and reduce biodiversity, highlighting the ecological risks associated with herbicide drift.
https://www.sciencedirect.com/science/article/abs/pii/S0269749121005352
Critical Review of Glyphosate Drift Effects (2017)
A comprehensive review analyzed data from 39 studies to determine safe drift exposure levels for various plant species. The review concluded that drift rates below 5 g a.e./ha would protect approximately 95% of higher plant species from minor adverse effects, with rates below 1–2 g a.e./ha offering near-complete protection.
https://pubmed.ncbi.nlm.nih.gov/28731230
Influence of Adjuvants and Nozzles on Glyphosate Drift (2015)
This study evaluated how different spray nozzles and adjuvants affect glyphosate drift. Air induction nozzles, such as the TTI 110.015, significantly reduced drift compared to conventional flat-fan nozzles. The choice of adjuvant also played a crucial role in minimizing off-target movement.
https://awsjournal.org/article/influence-of-adjuvants-and-spray-nozzles-on-glyphosate-drift
Spray Drift and Efficacy with Adjuvants (2020)
Field trials assessed the efficacy and drift potential of glyphosate and 2,4-D applications with various adjuvants. Results indicated that certain adjuvants could reduce drift without compromising herbicide effectiveness, emphasizing the importance of adjuvant selection in spray applications.
https://www.researchgate.net/publication/340803056_Spray_drift_and_efficacy_from_glyphosate_and_24-D_applications_with_adjuvants
Herbicide Drift and Resistance Development (2020)
A study found that repeated exposure to sub-lethal doses of glyphosate drift can select for weed biotypes with reduced herbicide sensitivity over just two generations. This highlights the role of drift in accelerating herbicide resistance in weed populations.
https://www.nature.com/articles/s41598-020-59126-9
Glyphosate Injury in Wheat Fields (2023)
An article from Kansas State University Extension reported instances of glyphosate drift causing white heads in wheat fields, a symptom of herbicide injury. The piece offers practical advice on identifying and preventing such damage.
https://eupdate.agronomy.ksu.edu/article/be-aware-of-herbicide-spray-drift-in-wheat-594-1
This isn’t a token list — it’s a solid foundation of research, field studies, and local regulatory guidance. Together, they show that spray drift is not just a nuisance — it’s a measurable, documented risk with real-world consequences. If this is what we know already, imagine what we haven’t uncovered yet.
Keep questioning. Keep watching. The science — and the accountability — is still unfolding.
Spray Drift Guidance and Best Practices in New Zealand
Protecting the Environment While Using Pesticides – EPA New Zealand (PDF)
A concise guide summarizing EPA rules under the Hazardous Substances (Hazardous Property Controls) Notice 2017. It explains practical steps to reduce spray drift, including buffer zones, weather considerations, and label compliance.
https://www.epa.govt.nz/assets/Uploads/Documents/Hazardous-Substances/Guidance/eff02bf97e/Protecting-the-environment-while-using-pesticides.pdf
NZS 8409:2021 – Management of Agrichemicals (17/08/21)
New Zealand’s national code of practice for agrichemical use. Although not legally binding, it outlines industry-recognized best practices for spray application, drift reduction, and environmental protection. Referenced by regulators and GROWSAFE® training.
https://www.standards.govt.nz/
(Note: Full document must be purchased via Standards NZ)
Agrichemicals Guidance for Business – EPA New Zealand
This EPA webpage provides detailed information on the legal obligations and best practices when using agrichemicals in New Zealand, with a focus on drift management, product classification, and safe handling.
https://www.epa.govt.nz/hazardous-substances/rules-notices-and-how-to-comply/specific-substance-guidance/agrichemicals/
Agrichemical Spray Drift — Risks and Rules
This official page from Northland Regional Council outlines the risks of agrichemical spray drift, including potential health effects, how far drift can travel, and the responsibilities of spray operators. It reinforces the need for signage, buffer zones, and precautionary measures in public and residential areas.
Northland Regional Council, New Zealand
If we can’t control where it lands, can we really call it safe?
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