Thursday, May 19, 2022

Keep an eye out for plant pest

Biosecurity New Zealand and primary sector partners are urging maize and corn growers to keep a close eye out for a crop-killing moth pest with potential to cost cropping farmers millions of dollars.

Fall armyworm (FAW) caterpillars were first found in Tauranga last month and now also identified on sweet corn and maize volunteers at two properties in Waikato.

Sweet corn and maize growers across the North Island are being asked to keep a watch out for caterpillars and report any signs of the moth pest.

Waikato Federated Farmers arable chair Keith Holmes said the new infestations are not just about risk to crops, but a huge part of the food chain for the dairy industry.

“We are talking potentially millions of dollars to NZ famers,” Holmes said.

“There is a massive amount of maize grown for dairy feed, this puts the maize industry under a huge amount of both financial and uncertainty pressure.”

Generally once FAW is detected the crops are past spraying by wheeled vehicles, leaving Heli-spraying the only option.

“That is really, really scary, at $1600-plus a hectare that is a huge cost,” she said.

Holmes said the current feed situation post covid and with the Ukraine war, is pushing prices up.

“We know that maize is going to be very expensive to grow next season and we also know that without this FAW there’s likely going to be at least a 30% increase in price to dairy farmers,” she said.

“Growers nor dairy farmers need the added cost to spray for FAW.”

While Biosecurity NZ’s risk analysis is predicting FAW will die off over the winter, Holmes is not convinced.

“We do know that FAW thrives in warm climates and it is thought that it is unlikely to successfully hibernate in colder climates such as NZ, other than in the far North where it has not yet been found, it is in Tauranga and Bay of Plenty does have a warmer climate,” she said.

“I’m sceptical; all we need is a mild winter and it’s fully established in NZ.

“Biosecurity in NZ does worry me – this is yet another straw on the camel’s back.”

Feds arable chair Colin Hurst believes FAW poses a serious risk to the industry.

“I’m concerned, where FAW has popped up in other countries it’s been bloody serious,” Hurst said.

“It’s a moving target, we still need to understand the issue and how the life cycle will work in NZ conditions.”

Feds is planning to meet with the Ministry for Primary Industries (MPI) to work through the implications.

The FAW moth is a plant pest that can feed on more than 350 plant species, but prefer grasses and cereals.

Meanwhile, Federated Farmers, MPI and the Foundation for Arable Research (FAR) are stressing the importance for growers to check their sweet corn and maize crops for the pest.

FAW adults and larvae are highly mobile, with a strong ability to fly and disperse during summer.

Adults can migrate up to 500 kilometres before laying their eggs and are also known to travel long distances on stormfronts.

Once in the armyworm stage and in large numbers they consume nearly all vegetation in their path.

Last month, a single confirmed egg mass belonging to the moth was found in Tauranga.

There has been a further find of caterpillars on corn and maize regrowth at two properties on the outskirts of Hamilton in the past two weeks.

“This moth has been on our radar for some time as it has been spreading around the world and we have been working closely with our sector partners on keeping it out,” BiosecurityNZ said.

It is present in the Americas, Africa and Asia, and is established in parts of Australia. 

It is thought the pest moth arrived from Australia via strong winds.

Fall armyworm adults are nocturnal and most active during warm, humid evenings.

Caterpillars on maize and corn crops or volunteer maize and corn in other crops will be the most likely easily identifiable sign of this pest.

If you believe you have seen a fall armyworm, either an adult, larvae or egg masses – take a photo, preferably top down, and call the Exotic Pest and Disease hotline on 0800 80 99 66 or report through the online report form at www.report.mpi.govt.nz/pest or via www.findapest.nz/ (download the app).

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