Growing challenges

Dr Brent Clothier, Principal Scientist at Plant & Food Research, is reluctant to be viewed as a Pollyanna when it comes to climate change, but he cannot fail to see a rosy side to a climate-warming scenario for horticulture (extreme events notwithstanding).

“There’s massive potential in areas that aren’t traditional horticultural areas, such as Taranaki. At present in New Zealand there are about 180,000 hectares under horticulture and arable farming. However, in terms of climate resources, there are around 2 million hectares that could potentially sustain these industries,” he says.

That said, there are significant value-chain issues that need to be overcome before Taranaki becomes another fruit bowl.

Clothier’s Plant & Food Research colleague Dr Jill Stanley echoes the positive sentiments. “I’m an optimist. I think New Zealand will do well as long as it plans well, including adaptations for more intense weather events. We have a huge opportunity to grow a wide range of crops successfully,” she says.

Plant & Food Research is just one of the growing body of organisations, including government departments, regional councils, research institutes and businesses, which are mapping out a path for the future as the planet continues to warm.

Industry body Horticulture New Zealand predicted in 2019 that by 2028 the land area in horticulture would have risen to 140,000 ha, with most export fruit growth expected in avocados, pipfruit and kiwifruit, while the greatest vegetable-growing expansion would be in potatoes, onions and process vegetables.

Victoria University climate researcher Professor James Renwick says climate change means more energy in the atmosphere, feeding into weather features. When there is fine weather under a big high-pressure system, everything dries out faster, it is hotter, and droughts occur more quickly. On the other hand, when there is a storm there is more water in the air, and more rain falls.

For vulnerable crops this could spell disaster, not that apples, cherries and lettuces have never been beset by damaging hail and downpours – just that these events will become more frequent and destructive.

Some of the mitigation measures that researchers are investigating include: covered cropping and precision irrigation, developing new varieties which will perform under hotter temperatures, changing the type of crop grown, and shifting the locations of crops. Others are more transformational as a way of protecting the $10 billion of value that horticulture and arable farming represent for Aotearoa.

In August 2019, the Government launched its draft National Policy Statement on Highly Productive Land, to ensure the country’s best growing land is not lost to lifestyle blocks and housing subdivisions.

“Every year we put 40,000 ha under lifestyle blocks, asphalt and infrastructure. The result is ride-on mowers and ponies instead of productive land,” Clothier says.

One cause for optimism: horticulture and arable farming have relatively modest carbon footprints. Nevertheless, companies such as T&G Global and Zespri Group Ltd are conscious of the need to cut down on waste and to lower greenhouse gas emissions.

“A good example of this is our current life cycle assessment of our own-grown apples we are conducting at present,” says Sustainability Manager for T&G Global Courtney Simpson. The company is aiming to be net zero carbon by 2050.

“At our Reporoa tomatoes site, Ecogas is building Aotearoa’s first large-scale food waste-to-bioenergy facility, which will recover 75,000 tonnes of organic waste and turn it into clean energy,” says Simpson. This will provide renewable electricity, heat and CO2 to enhance the growing conditions of our tomatoes – a fantastic carbon-neutral, circular alternative to natural gas.”

Changing tactics

One way to reduce the impact of climate change is to implement tactical adaptations and modify existing production practices.

“The day-to-day stuff stays the same, but flowering and harvest dates come earlier so you have to make a change, such as organising your seasonal harvest workers for different dates,” says Clothier.

Zespri, which generated $3.58 billion in global fruit sales revenue last year, sees the upsides in climate change, while not downplaying the downsides. It is possible that warmer temperatures and longer growing seasons could result in higher quality fruit, while some colder regions may become more suited to production.

To make sure they’re prepared for what the future brings, Zespri have created a “Climate Risks and Opportunities” report which outlines the physical climate risks and the tactical adaptations growers need to adopt. Among the risks are increases in pests and pathogens, and a reduction in budbreak because winter temperatures are not low enough.

Most kiwifruit orchards in the Far North rely on dormancy regulators to encourage budbreak, but the future of this approach is uncertain, with the Environmental Protection Authority proposing a phase-out of some chemical products.

Plant & Food Research scientists are working on new regulators while also keeping climate warming top of mind when developing new kiwifruit varieties. Stanley says that although climate change will open up opportunities in cooler regions, growers need not abandon their kiwifruit for a different crop.

“The more sensible strategy is to develop new cultivars that perform well in those climates. You can graft new cultivars on to kiwifruit vines quite quickly.

”T&G Global has teamed up with Plant & Food Research, the Institute of Agrifood Research and Technology (IRTA) and Fruit Futur, developing and commercialising apple and pear varieties which are climate change adapted. The “Hot Climate Programme” has recently commercialised ‘HOT84A1’, which was successfully trialled in Spain, where temperatures reach more than 40°C. The apple has proven to be sunburn resistant, whilst still good eating.

“The Hot Climate Programme is unique and addresses both climate change mitigation and adaptation”, says Morgan Rogers, General Manager of Operations for T&G’s VentureFruit business. “Not only will we be able to grow fruit globally in areas where temperatures are rising, we can also potentially extend into new regions previously not suitable for apple and pear growing.”

Stanley and her colleagues have been observing modified systems, like canopy covers, which protect or reduce the effects of some of the more expected intense weather events. In the last year kiwifruit and pipfruit orchardists in Motueka and cherry growers in Central Otago suffered significant losses from hail and severe rain.

While canopy covering cannot completely stop the damage from heavy rain, it does help. “When you look at things like the heavy rain that occurred in Central Otago last summer, there were growers who lost 80% of the crop. But those who had covers didn’t have anything like the same loss of crop,” says Stanley. “There was some flooding, but some of the trees that were covered had less than 10% splitting in the fruit.”

“We’re also working on developing new growing systems for some crops such as apples, cherries, apricots and pears,” Stanley says.

Stanley and colleagues have been trialling trees grown with very narrow row spacings of 2m between rows in a two-dimensional system — similar to traditional espalier growing, where the plant canopy is only 30–40cm wide — as opposed to a 3D system of a much wider tree. Not only have the yields been greater, but rain does not appear to hit the fruit to the same extent, and the canopy dries out faster because it is more open. The two-dimensional system could also reduce pests and diseases in future.

Still to be fine-tuned are the effects of covers on pollination. Honey bees can become disoriented under shade cloth, so bee behaviour scientists are working out strategies to avoid high bee mortality.

“We are also developing a virtual orchard for scientists and growers that mimics a real orchard,” says Stanley. We will create simulations to see what happens when we make changes — for example, by putting on a cover or growing the orchard in different climate conditions. We will then be able to run a scenario to see whether this improves the outcomes or not.” The use of canopy covers and two-dimensional growing systems in crops (like in this cherry orchard) may help reduce the effects of intense weather events.

A strategic approach

In its research – and sometimes practice – the horticultural industry is looking at adapting production systems in a more substantive way – termed a strategic adaptation; for example, changing the type of crop grown from apples to summerfruit.

And even if by comparison plants are not as thirsty as dairy cows, horticultural regions in the east of the country are likely to be more constrained by water supply.

Supported by funding from the Provincial Growth Fund via Kānoa – Regional Economic Development & Investment Unit, the Kaipara District Council has led the charge to future-proof its region against climate change with its Kaipara Kai project. Best known as the kumara capital of the country, the region has the potential to grow new crops such as peanuts, hops and sorghum, and to expand its avocado plantings. The project includes a full suite of research covering topoclimate and kai feasibility research as well as funding for an on-the-ground service centre (Kaipara Kai Hub) to operate for a period of time. Kaipara Mayor Dr Jason Smith says the region needed an “activation plan” to connect researchers and growers.

Innovation and transformation

Over the past 15 years, Plant & Food Research has worked with regional councils, companies and Māori entities to chart ways in which they can prepare for climate change by potentially developing completely new production systems and industries.

For successful growing of horticultural crops, each crop has several climatic pre-conditions required, and this can vary between cultivars of the same crop e.g. different kiwifruit varieties, and depends on the specific crop. However in general, many crops require a certain number of chill hours of 7°C or below between May and September; a certain number of accumulated heat units when the daily average temperature is 10°C and above (called growing degree days); and a frost-free period.

Clothier says one of the key findings from Plant & Food Research has been that existing farming operations can exist alongside new types of production.

“We did a study in Northland which showed that across conventional farms they had niche locations to support horticulture; they didn’t have to be a 100% dairy farm. It’s not about horticulture replacing a dairy farm, it’s about adding horticulture to existing land uses.”

In 2020 Clothier and others prepared a report for Venture Taranaki which identified there were about 207,000 ha of land potentially suitable for generic horticulture within the boundaries of the Taranaki Regional Council. It looked at the viability of eight mainstream crops that could offer commercially successful horticultural opportunities for the region’s land-owners.

But, as the Chief Executive of Te Puna Umanga/ Venture Taranaki, Justine Gilliland, points out, it’s not just a matter of whether the crops can be grown.

“Success will be achieved as much by these factors as by people, knowledge transfer, and the emergence of new chains, processing, and products to deliver these growing opportunities to market.”

Crops that were marked out as having promise were apples, avocados, blueberries, wine grapes, potatoes, hazelnuts and walnuts, hops, hemp and CBD cannabis. Clothier points out that changes to existing land uses require building up capacity behind the scenes.

“We did a job for post-quake Kaikoura, asking, ‘do we put fences back up and carry on as if nothing happened?’ There were some pretty neat river flats there, which might come under pressure from changes in water quality regulations. Rather than having a sharemilker, you might end up having a shared horticulturist.

“But one of the challenges is: where is the packhouse, coolstore, or the horticulture consultancy? There’s nothing like that in Culverden, so you have an infrastructural knowledge deficit. You need an investment strategy to support land-use change,” Clothier says.