Clear guidance on grass grub control options this season

Leading crop protection supplier Nufarm is reminding farmers and rural retailers that key organophosphate options for grass grub control remain available under current rules and timelines.

According to Nufarm portfolio solutions lead Duncan Ibbotson, recent comments suggesting widely used OP insecticides are no longer available risk leaving end users and suppliers with an incomplete understanding of what tools are still legally on the table.

“We’re concerned that growers and agronomists could be under the impression they can no longer use diazinon or chlorpyrifos products for grass grub control, and biological control is their only remaining viable option.”

Ibbotson says liquid chlorpyrifos may no longer be manufactured or imported after 8 January 2026, but farmers and contractors can still continue using existing product until 8 July 2026.

Granular chlorpyrifos products such as SuSCon Green remain available even longer, with use permitted until 8 July 2027.

Diazinon products such as Diazinon 20G and Dew also remain legal for on-farm use, with approvals not due to be revoked until 1 July 2028.

“These dates mean growers still have robust tools to manage grass grub while longer-term replacements are assessed and adopted, something that we’re continually assessing for new options to control NZ’s most damaging insect pest,” Ibbotson says.

He notes that biological options can play a role, but their efficacy may be more variable than organophosphate standards, so decisions should be based on pest pressure, timing, and product performance data.

As regulations continue to tighten, Ibbotson believes it is even more important that farmers understand precisely which tools remain viable during the transition, and make the most of being able to use them while they still can, potentially avoiding costs of disposal after the phase-out periods are completed.

He says clarity is essential in an industry where regulatory shifts are slow, technical, and highly consequential for farm performance.

Ensuring accuracy helps farmers make informed decisions while the sector continues its search for robust long-term replacements.

He emphasises that growers need confidence, not confusion, as they navigate one of New Zealand’s most stubborn pasture pests.