The first fall armyworms for the 2023/24 growing season have been confirmed in several places in Northland.
Northland farmers are being urged to be vigilant as the dreaded plant pest fall armyworm, which destroys maize and sweetcorn crops, has been spotted in the region.
Ash Mills, a biosecurity officer at the Foundation for Arable Research [FAR], said the first cases of fall armyworms for the 2023/24 growing season had been confirmed in several places in Northland.
These included three or four confirmed reports in different properties south of Whangārei including around Waipu, he said. There had also been two unconfirmed reports in Hikurangi.
The farms were all maize growers which can include dairy farmers who grow maize to feed their animals.
Mills said the discoveries meant the plant pest had successfully “overwintered”.
Fall armyworm, a type of tropical pest, usually can’t survive temperatures consistently below 10C.
“Fall armyworm’s minimum temperature threshold is around 10C and winter in Northland is typically a bit colder than that and it has been able to successfully overwinter. Now we’re finding the first cases.”
Fall armyworm is a plant pest that can feed on over 350 plant species, preferring grasses and cereals, especially sweetcorn and maize.
It was first detected in New Zealand in February 2022 after being carried on storm fronts from Australia.
The Northern Advocate reported farmers in the Far North were deeply concerned the pest was annihilating their maize crops, which hiked the cost of growing the essential feed while also producing devastatingly low yields.
However, Biosecurity New Zealand said fall armyworm couldn’t be eradicated and was here to stay.
Mills said it was “the first generation” of fall armyworms that had been found this season.
“They’re small numbers, nothing alarming just yet, but they [farmers] have to be vigilant in monitoring their crops.”
While initially there was “not a lot we could do”, the research organisation had switched to a long-term management plan since April to understand how widespread the pest was throughout the country.
It also wanted “to understand the weather and climate that fall armyworm can survive in over winter, and what it can feed on in the absence of maize and sweet corn”.
FAR now wants to collect data and get growers involved with collections to build on information from its monitoring and trapping programmes.
“We’re never going to get rid of it … even if it was a really cold winter there’s always the potential it can fly back over from Australia,” Mills said.
“It’s now long-term management, we’re trying to figure out how to control it.
“Like any other pest species in New Zealand, we can’t just leave it, we have to understand it … what damage is it going to do, what tools we have to manage it with so farmers’ crops don’t get destroyed.”
Though New Zealanders had been told to expect a dry and warm Christmas and rest of the summer, thanks to El Niño, Northlanders have experienced some unpredictable weather over the past few days including humidity and heavy downpours of rain.
Federated Farmers Northland president Colin Hannah said though he hadn’t yet come across anyone with fall armyworm “the humidity is just about right”.
“We’ll probably start to see it in another month.
“It’s in a number of crops now but will start attacking the maize crops a bit earlier.
“We’ve had enough rain and everything is moist, it’ll get these things going.”
Hannah said the pest was “very damaging” but there were sprays farmers could use on their crops.
“It can almost destroy a crop over two days.
“It lays a bunch of eggs in a cocoon – I’m not sure how many eggs, but looking at the size of it, it would be thousands, and it doesn’t take that many to go berserk.
“You have to be on the ball once you see it, you’ve got to get out there and spray your crop.”
Mills also suggested farmers “get out there as often as you can to identify any damage and identify what the pest is.
“It can be another species, and there are other control methods for those pests.”
Mills asked anyone who thinks they’ve seen fall armyworm to take photos and put them in the freezer and email him at: Ashley.mills@far.org.nz
Jenny Ling is a news reporter and features writer for the Northern Advocate. She has a special interest in covering health, food, lifestyle, business and animal welfare issues.