Undercover Operations

This article has been written exclusively for Food NZ, by the NZ Food Safety Science & Research Centre

This article was going to focus on the trend toward growing vulnerable crops like berries and salad greens under cover, and the advantages, if any, for food safety.

Then the weather intervened.

This story began, fatefully, on 13 February, with a phone call to Anne Marie Arts, leader of the NZ Food Safety Science & Research Centre’s Horticulture Taskforce.

Cyclone Gabrielle – the final, and worst blow

Waikato blueberry growers had lost all but 20% of their crops to a frost in October 2022. It was cruel. But that was just one in a series of weather disasters, coming at the end of a long stretch of cool and gloomy weather. Anne-Marie was still dealing with the fall-out from Cyclone Hale in mid-January, when lahars of perfectly finished Pukekohe onions spewed out over roads and filled gutters. As United Fresh representative, she immediately issued an urgent media release to warn the public not to eat any fruit or vegetables that had been in floodwaters. Existing grower protocols were clear – they simply could not sell any produce that had been partially or fully submerged.

As Anne-Marie lamented the tragedy for growers in Pukekohe and elsewhere, she watched through the window of her Auckland home as the pohutukawa tree in her garden started whipping around alarmingly, heralding the arrival of Cyclone Gabrielle, just one month after Cyclone Hale. No one then knew just what lay ahead that night.

Immediate response

The Centre offered the immediate assistance of its national network of scientists to support industry, however they could, and the Ministry of Business, Innovation and Employment (MBIE) quickly agreed to waive the usual requirement for industry to put in 60% of the funding for these urgent research needs.

“They are allowing the Centre to pay 100% of any cyclone recovery work, so we can just get on with it,” says Director Libby Harrison. Kyla Archer, the Centre’s Industry Research Liaison Manager is coordinating deliberations about what needs to be done with AnneMarie and other industry representatives. “There’s tremendous solidarity: everyone wants to help.”

Leaderbrand shows the way

Anne-Marie says these weather events will undoubtedly accelerate the trend to put more vulnerable crops under cover. For example, Leaderbrand in Gisborne is investing in a large indoor growing facility for their salad business, though the installation’s main driver was the ability to produce crops year-round, rather than protection against extreme weather. Food safety manager, Stefan Stewart, says that although they took a big hit in Gabrielle, losing a significant portion of their grapes, some other crops and all new outdoor plantings, they

Growers are moving towards growing vulnerable crops like salad greens under cover consider themselves pretty lucky overall when compared with other growers. Their new indoor facility and independent water supply from a dam they have built nearby, will hopefully future-proof production. The rainwater from their dam is passed through a multi-media filter system and then UV-treated to drinkable standard, which is imperative for food safety with vegetables that will be eaten raw. The water is usually only used for crop irrigation, but after Cyclone Gabrielle, the water has been delivered to packhouses in tankers so it can be used for washing prior to packing as well.

Gisborne lost both power and its main water supply for a long period. Leaderbrand was able to help out by providing water to other food and wine producers in Gisborne. Although many of the East Coast roads were closed by slips, Leaderbrand's trucks were still able to get their time-sensitive greens to distribution nodes in the main centres, albeit the very long way round.

Stefan says the future of vegetable growing is looking more and more likely to be indoors. “The capital cost is huge, and industry is still refining the processes, but Gabrielle has shown we need to be more resilient to extreme weather events in the future.

Undercover-growing less vulnerable

“When it comes to food safety, one of the advantages of growing indoors is that you have much lower risk of pathogens such as listeria, (which occurs naturally in the environment) splashing onto plants when it rains, or birds and insects depositing faecal matter.”

While outdoor blueberry crops in the Waikato withered irrecoverably in the October 22 frost, those under cover in the MIRO iwi/hapuowned and managed collective of 12 orchards around the North Island enjoyed substantial protection from wind, rain and hail, although

those in Northland, Gisborne and Tolaga Bay were still quite badly affected. The blueberry bushes are grown individually in 30 litre pots which rest on weed matting and are covered by long tunnels of plastic domed over semi-circular hoops. The temperature, and all inputs, are controlled. Plastic has been partially torn off in some locations, and in Tolaga Bay, 5000 of their 20,000 pots were blown over, damaging some of the shoots. The ground was up to 400mm in water but they only lost 200 plants altogether, plus 60 tunnel hoops. It remains to be seen what the long term effects on the plants may be of sitting in water for a period of time.

But MIRO CEO, Liz Te Amo has no doubt that all their orchards will harvest as planned from August to December. Despite the damage, she says, “The tunnels certainly offer good protection against rain and storms and allow you to continue harvesting when it rains – we were able to harvest the 2022/3 crop through some very inclement weather that would otherwise have made it impossible. And the tunnels give us complete control over how much water and fertiliser each plant receives.”

In Helensville (North-West Auckland), the staff of Superb Herb found themselves shin-deep in water, but their herbs were saved as they are grown on benches at waist level. However, the floods were just too high for a couple of table-top strawberry operations in Hawke’s Bay. All the plants had to be dumped.

Undercover pros and cons

Anne-Marie has the overview of our horticulture industries, and keeps close tabs on each crop. She says growing under cover is not a silver bullet when it comes to weather events or food safety and the transition certainly isn’t cheap.

“We must be very careful that the water used for irrigation and spraying is potable standard, and that staff picking produce like strawberries, which cannot be washed, observe strict hygiene practices. Managers must ensure good facilities are available for that. Then, sadly, there’s the emerging risk of food terrorism – for example, the addition of harmful substances to water and nutrient supplies.”

“With increasing competition for water, the trend to building dams, and collecting rainwater in tanks, comes with the risk of pathogens from birds in particular. So, it must undergo proper treatment, as Leaderbrand is demonstrating.”

There are two types of undercover operation – high tech, where everything is automated, and plants are grown off the ground, and simple overhead cover that protects from rain, wind and hail. Moving under cover is not a practical or economic option with fruit trees and vines, though netting and windmills/helicopters provide some limited weather and bird protection. Cherries, because of their high value, are an exception.

Strawberries grown at ‘picking height’ may be spared the ravages of flooding

Anne-Marie says, “Post Gabrielle, we are asking ourselves fundamental questions about where and how we should grow crops in future. Most fruit has a minimum winter chill requirement. The latitude band meeting that requirement is getting narrower and narrower.

“Cyclones Hale and Gabrielle topped a generally bad summer in the North Island. We were already experiencing existing shortages of supply (overseas growers have been hit with climate crises too) as well as inflation, and import/export shipping headaches that saw whole containers of grapes dumped after sitting around offshore for too long.

“It is great that everyone is pulling together to support our growers. The industry is trouble-shooting on a day-to-day basis, as best it can. For example, so much produce has been going from the South to the North Island that they’ve run out of plastic containers. In the short term, consumers are going to be facing some eye-watering prices, and a more limited range of fruit and veg. They’ll need to be flexible, substitute where they can, and not necessarily judge a fruit by its appearance. Frozen veg is always a great option, too.

“We won’t know the final reckoning until October. We’ll have all the numbers then for the fruit and other crops we have managed to get to market. United Fresh compiles all the statistics in its publication Fresh Facts.

Libby Harrison says, “Growers and grower organisations deserve a lot of credit for holding the line on food safety. There has never been any question about compromising standards, despite the horrendous losses involved. It is extremely hard. We are totally focused on doing our bit towards long term recovery.”