The decision by the Environmental Protection Authority (EPA) to ban the insecticide chlorpyrifos directly impacts farmers and growers who use it to control pests. The announcement led to concern from the primary sector over losing a weapon against grass grub, nysius, and Argentine stem weevil. While chlorpyrifos was banned immediately in public places, like parks and sports fields, the EPA have given farmers and growers a longer phase-out process of 18-months.
Why the ban?
Chlorpyrifos is a broad-spectrum organophosphate insecticide. Though effective against a range pests, because it is a non-selective substance, it causes harm to non-target species. The harm it causes is not temporary. It remains behind in the soil and is toxic to aquatic life and bees. For people, it is a neurotoxic agent leading to neurological damage and developmental effects in foetuses and children. Without a way to mitigate the harm, the EPA determined they outweighed any benefits.
“Even with all of the safety measures we could put into place, even with personal protective equipment—mask, gloves, overalls—there was still potential harm to people using the chemical,” says Dr Shaun Presow of the EPA.
What next?
The EPA's announcement had pushback from the primary sector. Grass grubs and other invertebrate pests cost the pastoral industry an estimated $140 to 380 million a year on dairy farms, and $75 to 205 million for sheep and beef.
However, PGG Wrightson Technical Specialist for Agronomy Joseph Watts says we have more than one option to combat pests.
“Just because we are losing a tool from the toolbox does not mean we are defenseless. The problem is it was not selective at all about the insects it would control, it would hit everything in its path, including the user.
“The good news is New Zealand recently registered two new specialised insect control tools, one is a new mode of action here,” says Joseph.
Integrated Pest Management
A greater reliance on specialist products will be safer for beneficial insects, operators, contractors, farmers, and growers.
“Products like chlorpyrifos are effective against pests becausethey kill everything in their wake, but Integrated Pest Management (IPM) tools, lets mother nature do the dirty work for you,” explains Joseph.
Integrated Pest Management uses cultural, biological, and selective chemical insecticides to effectively control pests in crops.
“Rather than an agrichemical being your first port of call, IPM uses them sparingly, selectively, and only when absolutely necessary, to protect beneficial insects who survive to do the work instead,” Joseph says.
Next steps for PGG Wrightson
As a business, PGG Wrightson has been trending away from organophosphate based products for several years.
Their tech and store teams are well equipped to offer advice on managing pests without them, particularly around adopting IPM practices.
In December, PGG Wrightson will no longer sell chlorpyrifos products.
Between now and then, all products sold will be on a non-returnable basis.
“Stockpiling is a bad idea. While I understand the impulse, it must be used before July 2026 or you will have to pay to have it disposed of in line with EPA controls,” says Joseph.
“Now, is the time to adopt new control methods, so pop into PGG Wrightson for some advice.”
Ferguson, C. M., Barratt, B. I. P., Bell, N., Goldson, S. L., Hardwick, S., Jackson, M., Wilson, M. (2018). Quantifying the economic cost of invertebrate pests to New Zealand’s pastoral
industry. New Zealand Journal of Agricultural Research, 62(3), 255–315.
suSCon and PYRINEX 500EC. These chlorpyrifos products will no longer be sold at PGG Wrightson after 19 December 2025.
The new toolbox
Chlorpyrifos is used to target four major pests: grass grub, porina, Argentine stem weevil, and nysius. PGG Wrightson's Joseph Watts walks us through our options for controlling them.
Grass Grub
- Diazinon (to be banned in 2028) remains the go-to option for grass grub control in existing pastures.
- Seed treatments offer a level of protection during establishment of ryegrass.
- AR37 endophyte in ryegrass offers low level protection over the long-term.
Porina
- Diazinon and diflubenzuron remains the primary chemical control options.
- Good endophyte selection offers a level of control over the long-term and is worth investing in.
Argentine Stem Weevil
- Attack (pirimiphos-methyl and permethrin) is the only active ingredient registered in New Zealand for control in forage brassicas and fodder beet.
- Seed treatments for brassicas and grasses provides protection during the establishment period.
- Endophytes protects ryegrasses over the long-term.
Nysius
- SIVANTO Prime (flupyradifurone) is a newly registered insecticide that is also a new mode of action for New Zealand. It is registered for use in brassicas and fodder beet and is particularly useful during the crop establishment phase.
- Twinguard (sulfoxaflor and spinetoram) is a new registration for use in brassicas.
- Mavrik (tau-fluvalinate) and Attack (prirmiphos-methyl and peremethrin) are labelled for use in brassicas and fodder beet.
