Eliminating Pea Weevil

May 2020

Elimination of pea weevil in the Wairarapa

In 2016 an infestation of pea weevils in Wairarapa meant arable farmers in the region, had to forego profitable pea seed crops in an effort to eradicate the pest. It was a significant industry, community and biosecurity effort. Four years on, the process was declared successful, believed to be a world first.

In 2015 Rural Delivery met Karen and Mick Williams, the supreme winners of the Greater Wellington Ballance Farm Environment Awards 2013. The judges described their 224ha arable and livestock finishing farm business as “an outstanding farm run by an inspirational young couple”.

In 2015, growing peas for seed was the Williams’ most profitable crop. Unfortunately, during the following season, pea weevil was discovered in Wairarapa. This pest, if established, would severely impact our export seed market. As the weevil was found relatively early and in only one region - and as the pest relies for its survival on a very narrow food source (peas), the decision was taken to attempt to remove this food source, cause the population to die out, and so eradicate the pest.

While this approach meant there was a strong likelihood of preventing the spread and establishment of the pest across New Zealand, it caused issues for the Williams’ and fellow Wairarapa growers that had to be addressed.

Karen was appointed as grower representative on the Biosecurity New Zealand governance group to help determine the best response, and an effective and fair policy to deal with that.

The pea weevil (Bruchus pisorum) is a small insect that can cause damage to growing peas and is an “unwanted organism” under the Biosecurity Act 1993.
When pea weevils were found in the Wairarapa it was vital to stop them from spreading to other parts of New Zealand where they could have a serious effect on pea growing and processing industries.
Biosecurity New Zealand worked with local growers to place a minimum two-year ban on growing green peas (including sugar snap and snow peas) in the area. This included home gardens as well as commercial crops.
Prior to discovery of the weevil the Williams had been growing around 36ha of peas for seed annually. Their no tillage system used a cross-slot drill to sow seed in late October or early November for harvest in February, with the seed going mainly to commercial growers in the Hawkes Bay and baled straw sold to gardeners.
Eliminating peas from their cropping mix put the Williams and growers like them at a considerable disadvantage, as Mick explains: “Peas were our most profitable crop and so we lost income. Some advantages of peas are that they are harvested earlier than other crops and so the area can be put back into winter grasses earlier,” he says. “The grass crops establish better because of the nutrient value that the peas return, so we can graze it earlier and finish more lambs. It's a bit hard to put a definitive figure on the added value this gave pea crops but they certainly gave us an advantage.”
In place of peas, Mick has grown more ryegrass for seed and more barley. That has meant increased fertiliser use and a reduced range of agri-chemicals, increasing the danger of developing herbicide resistance.
The pea weevil situation resulted in Mick’s wife Karen Williams becoming involved in representing Wairarapa farmers at various levels. A graduate in regional and resource planning, she took part in the 2015 Agri-Women’s Development Trust Escalator programme, a 10-month leadership and governance programme for women involved in primary industries.

“In March 2016 pea weevil came into my life and I was appointed to MPI's governance group as the grower representative. We discussed what the best response options were and agreed that we should give eradication a shot, which meant a growing ban for at least two years,” says Karen.

“That was the first really challenging experience of governance for me. I felt that giving eradication a go was the right thing to do but I said that we had to wrap support around growers – you couldn’t just whack off one of the most profitable crops and not help them through that transitional period.”

Karen advocated for compensation. This hadn’t been considered because the Biosecurity Act provides only for destruction of the crop whereas the ban was designed to prevent people from growing it. “It was a different scenario, so after a number of conversations over many months we agreed on an ex gratia payment to make sure no-one was worse off. Growers had to decide on an alternative crop and/or livestock and had to work out through a reasonably complicated process the difference between what they would yield from peas and what they got from the alternative crop. The ex gratia payment was to help fill the gap,” says Karen.

“It was tricky because you had to average the number of hectares you had in peas in the past three years – which wasn't too difficult – but then you needed to work out all the costs of producing the alternative crop on that precise area. It was complex for Biosecurity New Zealand and for growers, and that has been a real challenge over the past three years.”

The lucrative contracts that Wairarapa pea growers had to relinquish were taken up by Canterbury growers, and Karen asked what Canterbury could offer them as a swap. Unfortunately, nothing was particularly forthcoming, says Karen. “So, a number of us got together and applied to government for funding for a future focused cropping strategy so that we could trial different crops, like linseed or chickpeas, to determine whether there was another shining light that we could get on board with,” she says.

“The trials showed that we could grow number of other things in terms of soils, agronomy knowledge and expertise, and availability of water but they also showed that you needed to develop markets first, and that's a chicken and egg thing – great, we can grow linseed but who wants to buy it?”

“That has been a real learning curve for us. There are still trials going on with milling wheat because the North Island imports a lot of wheat from Australia, so we are looking at growing wheat for bread and baked products. We are also trialling some other wheat varieties – the fires in Australia may mean that there is less availability of cereals from there and that may be an opportunity for the industry. Some growers have looked at hemp. It has certainly forced people to think a little bit differently, which is a good thing.”

Subsequent to her involvement with the pea weevil governance group, Karen became the Arable Industry chairperson for the Wairarapa, and in 2018 was appointed as Federated Farmers’ national arable industry group chairperson and joined the Fed’s board.

Trap crops (mini pea crops established around the region) have shown that weevil populations have fallen dramatically. Trap crops are designed to attract the pea weevil and because the weevil can only reproduce on a pea flower these trap crops are closely monitored by Assure Quality, which captures and counts any insects at flowering and then destroys the crop.

“Three years ago there were over 1700 found in the trap crops, the following year there were only 15 found and only on two sites. Last year we had none and this year we hope to have none again,” says Karen. Shortly after we filmed this story, this was proved to be the case.

Mick is keen to begin growing peas once more. “The Wairarapa is a good region for growing excellent quality seeds and it is also closer than Canterbury to the main markets in Hawke's Bay and Gisborne. We would like to get back up to between 30 and 40 ha of peas again,” says Mick. “We will also continue to do riparian fencing and planting and fence off some special areas, and we will continue to improve nutrient management with testing and applying the correct amounts for particular crop requirements.”


Showdown Productions Ltd - Rural Delivery Series 15 2020