Purchased Maize Identified as Likely Source of Velvetleaf Incursion
Tracing has indicated that the source of the first velvetleaf find of the 2025-26 crop season, in Auckland, was likely maize purchased in the Waikato region.
Until this find, it was thought the only pathway had been through contaminated fodder beet seeds.
As of last week, there were 169 confirmed cases of velvetleaf in 11 regions throughout New Zealand. Canterbury has recorded the highest number to date (88).
Darion Embling, the team leader, pest plants, at Waikato Regional Council, says velvetleaf has been confirmed in maize and silage at several sites. He says it is unclear as yet how it came about. It could be via animal feed, manure or machinery, but none were confirmed when he spoke to Rural News last week.
Embling says this pest threat is bad: it could cause up to 30% crop loss. The Waikato Regional Council has put about 20 staff on the job.
"We are doing a whole lot of tracing in Waikato at the moment trying to nut out where all the linkages are," he says.
"Animal feed is showing up as possible – it is a common theme. For that to be confirmed it would need a lot of testing and council is not resourced to do that."
It is relying on the Ministry for Primary industries, but it was unconfirmed whether MPI would do that.
"If farmers have received any manure from any source and they've put it on their maize crop then they should check their maize crop for any weeds," Embling says.
"If they have received maize silage from elsewhere also, they should check where that has been fed out on the farm. They should check around silage pits to see what is there."
An unconfirmed possible pathway is any manure-type fertilisers where the animal has been grain fed. The seeds go through the guts of most animals.
"Any manure you are bringing on – that is fed on any sort of grain – palletised, unpalletised grain – then check those areas for velvetleaf and if they've turned those areas into a crop, even more so check those areas," Embling adds.
"We need to make sure people are checking their crops for anything that is different.
He says if farmers have any findings of velvetleaf, they should telephone MPI exotic pest/disease hotline: 0800 80 99 66.
They should take a photo of it and record the site, but do not remove the weed as it spreads the seeds.
"There's a lot of fear out there over this and we are trying really hard to manage the welfare of farmers also," says Embling. "They are under stress now anyway and this is another thing they are going to have to deal with."
Meanwhile, Guy Wigley, Federated Farmers arable chairperson, says Canterbury has inspected 80% or more of its target farms. The farms that sold the seed have been identified. Other areas have not got that far.
He says MPI has been working with stakeholders and doing a good job. They are looking at ways of tightening import standards.
MPI warns the window of opportunity for controlling plants that haven't yet seeded is narrowing and it's important farmers in all areas remain on the lookout.
Industries response manager Carolyn Bleach says farmers and landowners need to maintain a watchful eye until crops have been grazed, particularly as some late emerging plants have been found in crops already inspected.
"It's become apparent that velvetleaf shoots up dramatically when it goes to seed. A plant that may have been hidden by the canopy of the crop one week can appear a week or so later."
