When a pesticide is banned, it is tempting to think that is the end of the story.
Its use ends. It disappears from the market. Farmers move on to something else.
But what happens to the containers, bags and drums that were already purchased?
What if they are sitting at the back of a farm chemical shed?
And perhaps the more interesting question: does anybody actually know how much banned pesticide is still out there?
New Zealand has been dealing with exactly this problem for decades.
A Legacy Of Banned Pesticides Hidden In Rural Sheds
From the mid-1940s through to the 1970s, persistent organochlorine pesticides including DDT and dieldrin were widely used in New Zealand [PDF] agriculture, horticulture and timber treatment.
Their use was progressively restricted, and by the mid-1970s agricultural use of these persistent organic pollutants had effectively ceased. All of the pesticides subsequently covered by the Stockholm Convention on Persistent Organic Pollutants were formally deregistered by New Zealand’s Pesticides Board in 1989 — the former pesticide regulator, whose functions were later absorbed into New Zealand’s new hazardous-substances regulatory system, now administered by the Environmental Protection Authority (EPA).
But stopping their use did not make the products that had already been sold disappear.
Years later, significant quantities remained stored on rural properties.
In 2002, the Ministry for the Environment estimated that 282 tonnes of “intractable agrichemical pesticides” remained in New Zealand [PDF].
A national collection programme followed.
Between 2003 and 2006, the Ministry and 13 regional councils collected agrichemicals mainly from rural properties. By June 2006, the programme was expected to have collected approximately 290 tonnes of material, including around 225 tonnes classified as intractable agrichemicals.
Yet even after that substantial effort, the Ministry estimated that another 175 tonnes remained to be collected.
That is the part of the story that caught our attention.
The programme had removed hundreds of tonnes of chemicals.
And hundreds more had apparently still been sitting somewhere.
View the original Ministry for the Environment report
Some Regions Still Had Tonnes Remaining
The regional differences were substantial.
The Ministry estimated that 77 tonnes remained in Waikato, 34.1 tonnes in Canterbury and 25.7 tonnes in Wellington. Otago was estimated to have another 11.6 tonnes, while smaller quantities remained elsewhere.
Importantly, even regions recorded as having zero tonnes were not necessarily completely clear. The Ministry cautioned that “there are probably still small amounts of intractable material present.”
The Ministry acknowledged just how difficult the exercise was. Intractable agrichemicals, it said, were often “at the back of sheds and not easy to quantify.”
The Collection Never Really Stopped
Today, unwanted agrichemicals can be disposed of through Agrecovery, an accredited product stewardship programme.
Agrecovery says it has recovered 173,952 kilograms of unwanted chemicals since 2009 — nearly 174 tonnes. It provides free or subsidised disposal for many products, while disposal of products not covered by participating brands may involve a charge.
Depending on the chemical, collected products are currently disposed of either in New Zealand or overseas, including in France.
WorkSafe also directs people with unwanted farm chemicals to appropriate disposal rather than simply getting rid of them themselves.
Its guidance is explicit: chemicals should not be burned, buried, poured onto the ground, put down drains or discharged into waterways.
A Pesticide Ban Doesn’t Necessarily Mean Immediate Disposal
There is another important point.
When the EPA “bans” a pesticide, every container does not necessarily become illegal overnight.
There can be a managed phase-out, with different deadlines for importing, manufacturing, using and disposing of different products.
Chlorpyrifos is a very current example.
In July 2025, the EPA decided to revoke all approvals for substances containing chlorpyrifos after concluding that the risks associated with its use outweighed the benefits.
But the approvals were given different phase-out periods.
Depending on the approval, existing stocks had to be used or disposed of by 8 January 2026 or 8 July 2026, while the final two approvals have until 8 July 2027.
Similarly, everyone holding products containing chlorthal dimethyl was required to dispose of them by 18 June 2026.
So when we read that a pesticide has been “banned”, the next question should sometimes be:
When does the ban actually take effect — and by when must existing stocks disappear?
This isn’t merely a story about DDT drums left over from another era.
Some chlorpyrifos approvals reached their final disposal deadline only two months ago, in July 2026. The final two remain in phase-out until July 2027.
EPA advice tells holders to check their inventories and prepare for disposal.
But ultimately, that process depends upon those products being identified.
A container pushed to the back of a shed can remain there until somebody deals with it.
But Who Knows What Is Still In The Shed?
This is where the story becomes less clear.
New Zealand unquestionably has systems for collecting and disposing of unwanted agrichemicals.
It has undertaken major national and regional clean-ups.
It has legal requirements for the handling and disposal of hazardous substances and specific controls applying to persistent organic pollutants.
But that is different from knowing what remains on every property.
The 2006 Ministry report itself was an estimate of what remained after collection programmes. Some regions were considered clear; others were thought to retain substantial quantities.
And the continuing recovery of unwanted agrichemicals tells us that chemicals continue to emerge from storage.
Agrecovery’s nearly 174 tonnes recovered since 2009 came after the earlier national clean-up had already removed hundreds of tonnes.
That doesn’t mean all those later chemicals were banned pesticides — many will simply have been unwanted or obsolete agrichemicals.
But it does illustrate the difficulty of treating a regulatory ban as though it automatically removes every physical container from circulation.
New Zealand’s Pesticide Disposal System Is Changing
On 7 September 2026, the Government announced a new regulated Rural Recycling Scheme, due to begin on 1 March 2027.
The new nationwide system will bring specified agrichemicals, their containers and other farm plastics into a regulated product stewardship framework operated by the not-for-profit Agrecovery Foundation.
Producers of covered products will be required to register and pay fees towards the scheme, funding a nationwide take-back service.
The Government says recycling services will operate alongside collection services for agrichemicals, making it easier to deal safely with unused products.
That appears to be an important improvement.
But even the best disposal system still has to confront an extraordinarily simple problem:
you can only collect chemicals once they have been identified and brought into the disposal system.
Banned Doesn’t Mean Gone
Perhaps that is the lesson from New Zealand’s experience.
A pesticide can disappear from shop shelves long before it disappears from the country.
DDT had effectively ceased agricultural use decades before government collection programmes were still removing tonnes of it from rural properties.
More recent pesticides such as chlorpyrifos now have formal deadlines requiring remaining stocks to be disposed of.
And unwanted agrichemicals continue to be collected today.
So when we hear that New Zealand has “banned” a pesticide, there are really two different events.
One is regulatory: the decision has been made to prohibit or phase out the chemical.
The other is physical: the last container has actually been removed and safely disposed of.
History suggests those two things can be separated by many years.
And that leaves a question for which we have not found a current national answer:
How much banned or obsolete pesticide is still sitting in New Zealand sheds today?
Image Source & Attribution
The feature image on this page was created using AI-assisted image generation from an original concept developed by No More Glyphosate NZ and refined for publication in Canva.
AI is a useful creative tool for visualising complex investigative topics that cannot be meaningfully photographed, allowing us to illustrate ideas without implying that any specific scene or event actually occurred.
