The arable sector and the Ministry for Primary Industries are developing a pest management approach to better control the spread of fall armyworms.

The pest, which can munch its way through more than 350 plant species including maize and sweetcorn, is believed to have blown over to New Zealand from Australia after a cyclone in early 2022.

Eradication has been ruled out, but the arable industry has been working hard to contain its spread.

After a year of battling the pest, MPI and industry partners have agreed to close the response and shift the focus to long-term management of the pest.

Biosecurity New Zealand deputy director-general Stuart Anderson said it was collaborating with the Foundation for Arable Research, Process Vegetables NZ, Vegetables NZ Inc, and growers on management and mitigation strategies to help reduce production losses and enhance resilience to the invasive pest.

"Together we'll develop some really good tools for growers, including establishing surveillance networks on a national scale.

MPI is putting $300,000 towards the $630,000 three-year programme of work through the Sustainable Food and Fibre Futures fund.

Photo: Foundation for Arable Research

The impact of the fall armyworm infestation into the winter was unknown, Foundation for Arable Research biosecurity officer Ashley Mills said.

"It depends largely on our winter temperatures and suitable host plants in the absence of maize and sweetcorn.

"For instance, in areas with warmer winter temperatures such as Northland, the insect has the capacity to overwinter and survive all year round, with warming temperatures, we might expect the problem to grow year on year."

Part of the programme would be to identify gaps of knowledge around the winter growing season and dispersal of fall armyworm, Mills said.

"We'll produce models and come up with early warning tools for agronomists and growers, so they understand when they need to employ their most intensive management strategies.

"There's no one-size-fits-all solution, and approaches may vary according to factors such as region, climate or soil type."

In most cases, encouraging beneficial insects would work, but in more problematic regions or localities, insecticides might be needed, and the timing of application would be important, Mills said.

"Over the next three years, we'll focus on understanding fall armyworm phenology and distribution, developing New Zealand-specific economic thresholds and finding long-term solutions that reduce reliance on agrichemicals, and preserve soil health, water quality and biodiversity."

This story was originally published by RNZ