Tracing shows purchased maize the likely source of first velvetleaf find this season

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.

The velvetleaf was found on a dairy farm that both grows and purchases maize. 

North Island velvetleaf coordinator Sally Linton, who is employed on behalf of the North Island regional councils, Auckland Council and the Foundation for Arable Research, says the plants were discovered in pasture where last year’s maize had been fed out and along a fenceline beside a maize paddock.

“A big focus of the work we do in velvetleaf control is the tracing of machinery and crop movement, so we can establish and mitigate the source of spread.” 

“In this instance, no plants were found within the maize crop itself, which indicates that the incursion was not from machinery. 

“Also, the plants were not clustered together, suggesting this was a recent incursion – if they were clustered together, that would indicate that plants had seeded. 

“So, looking at where the plants were found and their distribution, it is likely that the source of the incursion was purchased maize, and tracing this farm’s purchased maze has indicated that the likely source was a maize purchase from the Waikato region.” 

Sally says a positive outcome of the find was the farmer knew what velvetleaf was and reported it immediately.

“This quick action ensured biosecurity staff could work quickly to contain the incursion and reduce the risk of further spread on or off the property.” 

The incursion provides a timely reminder for farmers who may be purchasing maize this season to check the crop in case it is contaminated with velvetleaf.

“Likewise, contractors should understand the biosecurity risks of the crops they’ve been asked to harvest and have a plan in place for managing weeds like velvetleaf.

“Even if you’re only harvesting maize for your own use, make sure the contractors working on your property use clean machinery and equipment. 

“The time and any cost spent on ensuring good biosecurity is an investment in protecting your land and business.” 

Velvetleaf is classified as an Unwanted Organism under the New Zealand Biosecurity Act 1993.

This means it is illegal to knowingly move, sell, propagate or distribute velvetleaf plants or seeds. 

Suspected sightings of velvetleaf should be reported to your regional council or Sally Linton sally.linton.nz@gmail.com.