Meet the man who saved New Zealand’s billion-dollar kiwifruit industry from disease – Stuff.co.nz

It is no exaggeration to say that kiwifruit have been Russell Lowes life. For more than 50 years as a plant scientist, the New Zealand scientist has been devoted to the little green, gold and now red fruits formerly known here as Chinese gooseberries.

But his contribution was perhaps best summed up when he was presented with the Plant Raiser's Award by the Royal New Zealand Institute of Horticulture last year.

In a speech when he was presenting the award, RNZIH president Dr Keith Hammett said Lowe was widely considered to have saved New Zealands entire kiwifruit industry after it was devastated by the virulent bacterial disease PSA (Pseudomonas syringae pv. actinidiae).

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Russell Lowe (centre) with orchard workers David Green (left) and John Muir, who were developing their own kiwifruit orchards nearby in Te Puke. Circa 1974.

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Kiwifruit is part of the Actinidia genus native to temperate eastern Asia. The seeds were first introduced to this country in the early 1900s and we began exporting the fruit to the United States in the 1950s.

When Lowe arrived on the scene a couple of decades later, the industry was still young. He turned up at Plant & Food Researchs orchard in Te Puke to find there wasnt much orchard to be seen, only some blocks of land lined with poplar trees that had been planted out as shelterbelts.

With the help of a local farmer and technical support from DSIR (Department of Scientific and Industrial Research) in Mt Albert, he got cracking.

It was an interesting time, Lowe said. We didnt have an office or any facilities and my wife Veronica was our unpaid telephone lady sometimes. At that stage kiwifruit was a minor crop in the Bay of Plenty. We were also looking at citrus, subtropicals and a whole range of fruits.

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PSA plant symptoms on the kiwifruit vine.

Things have changed a lot since then. There are now about 60 workers on-site and 40 hectares of fruit planted for research along with coolstores, laboratories, greenhouses and a packing house the whole shebang, as Lowe puts it. The facility is an important part of what has become a hugely successful horticultural industry, worth billions to New Zealand.

And when things went wrong, it was the breeding programme here that saved the day.

Back in 2010, a virulent strain of PSA was detected in New Zealand that was known to have decimated orchards overseas. PSA attacks the vigorous shoots of the vine and overwhelms its natural defences, causing canker. It threatened the whole industry and the gold kiwifruit variety, called Hort16A, that Lowe had been involved in developing, turned out to be especially susceptible.

That was a heartbreaking time for growers, as vines perished and orchards had to be ripped out. At the Te Puke research orchard, Lowe and his team also experienced huge losses.

We were in a disastrous state with Hort16A, he recalled. But monitoring some of our newer material, we found another gold cultivar that was showing really good tolerance to PSA. It wasnt completely immune, but as neighbouring plants were dying, this one wasnt.

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PSA culture on agar.

Originally known as Gold 3, now Zespri SunGold, the race was on to distribute this new hardier variety to growers that had been hit hard by PSA.

Cross-breeding kiwifruit is usually a slow and steady job. Parental trials take time and the process is painstaking.

Both a male and female plant is required to breed. Prior to the female flowers opening, they are covered with bags to protect them from our natural pollinators. Pollen is taken from male plants and once the female flower is open and receptive, it is transferred over and the bag is closed up again.

Later on, once flowering has finished, well take off the bag and wait until harvest time to extract the seed and then grow new seedlings, said Lowe.

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There is wide variation seen across the kiwifruit species.

A typical gold kiwifruit might supply 300 seeds. Around 200 or so will germinate and then 90 per cent of the male plants are discarded as the breeder only needs enough to provide pollen for the next generation of females.

Once the new seedlings have grown and started fruiting, the results are analysed, and then the best parents are selected and crossed again.

Lowe says its about a five-year cycle from making the cross to evaluating the progeny. As breeders, we dont just say, OK weve done it, we can stop now. We like to keep moving forward and improving, he explains. Having that continuous breeding programme was what gave us the resistant material to work with when PSA hit.

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PSA hasn't gone away, but growers have learnt to cope with it, and good orchard management are still able to produce healthy crops.

Lowe was already pretty sure he had a winner with SunGold as the vines were producing a large, well-shaped fruit with a really good taste.

Once we had enough fruit, we discovered its storage life was much better than Hort16A and then when people started growing it, they were getting really good yields and prices, he said.

Most likely SunGold would have ended up edging out Hort16A eventually but it might have taken a decade for growers to chop off existing plants and graft on new ones. The arrival of PSA meant the whole process had to happen much more urgently.

Today, PSA hasnt gone away, but growers have learnt to cope with it and with good orchard management are still able to produce healthy crops. Were still living with PSA every day on our research orchard, said Lowe. With our seedlings we dont put on any protective sprays as we want to find the most resistant plants to a range of problems.

There are other PSA strains out in the world and the Ministry for Primary Industries (MPI) has border controls in place.

TOM LEE FAIRFAX MEDIA NZ

Kiwifruit growers talk about the impact of PSA. This video was first published in 2017.

The South Island has none of the more virulent form of PSA and the plan is to keep it that way. Kiwifruit Vine Health has strict regulations governing anything in the Actinidia genus, as even plants that are resistant to PSA can harbour the bacteria. There are rules around plant movement and the locations of all properties where kiwifruit is grown are recorded.

This means there are lots of barriers to the home gardener who wants to grow their own. For a start you need plenty of space. Lowe advises at least eight square metres for a decent canopy and space alongside it for a male to pollinate. And currently you can only buy the green Hayward variety, sourced from a small number of registered nurseries.

Home gardeners are asked to manage the vines in the same way as a commercial orchard would: pruning and tying down vines by October 1 each year since PSA thrives in unpruned, heavily layered canopies; and, picking the fruit by July 1 to avoid birds eating it and spreading the seed (almost 20,000 wild kiwifruit vines were destroyed last year).

A spray of the copper fungicide Nordox in spring will help reduce the amount of PSA which may develop on vines in North Island locations. And you are not allowed to sell the fruit, propagate plants or move them between properties.

If you remain determined, then Kiwifruit Vine Health (info@kvh.org.nz) encourages home orchardists to contact them for advice and information on which nurseries may be able to supply plants. It may seem a lot less hassle to buy your kiwifruit from a grocery store and before too long you should be able to find the new red variety that Russell and the team have been busy developing.

Red kiwifruit was a mutation of the gold which Russell says originally occurred in the wild in China. A red-fleshed version, known as Hongyang, was commercially planted there after 20 years of breeding and selection.

It was quite well received in the Chinese market, but when PSA came along it wasnt particularly resistant, said Lowe. Weve been working on reds since 1997 and prior to PSA thought we were making quite good progress but then discovered it was just as susceptible as Hort16a and we lost probably 90 per cent of our seedlings to disease. But we found some that were surviving and from those we made new crosses, and thats where this new red has come from.

Known as Zespri RubyRed, it is sweet, with a delicious berry taste and that it looks great when cut open. Last Christmas, I put red kiwifruit on a pavlova for my family and it looked fantastic.

Work on the red variety continues, as breeders look to improve fruit size and storage life. Since there may be other pests and diseases out there there are concerns about the brown marmorated stink bug the strategy is to breed material with a reasonably wide genetic background so at least some plants will hopefully cope with whatever comes along.

Lowe has now retired from his full-time role and is an honorary fellow popping in occasionally to see how things are going. Because breeding is a long-term project there is material I was working on before I retired and Im interested in seeing what the outcomes are.

While Lowe may not be actively breeding kiwifruit any more, he is enjoying being able to eat them purely for pleasure. When I was working full-time, you might have to eat 20 or 30 samples a day at assessment time, so you didnt want to go home and eat more kiwifruit, he says. Now I enjoy the gold and the red.

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Meet the man who saved New Zealand's billion-dollar kiwifruit industry from disease - Stuff.co.nz