Resistance Revolution: Growing vineyard resilience

In March this year, Riversun received its first consignment of disease resistant varieties (DRVs) from Europe, with attributes that incluide resistance against downy and powdery mildew.

The DRVs are not derived from genetic modification or genetic editic, but rather technology that enables swift identification of resistance characteristics in plant DNA. They're not bulletproof, and Geoff prefers a reference to "resilience" over "resistance" but they could be a game changer in drastically reducing the need for sprays.

The global wine industry is facing the challenges of climate change amid the growing sustainability demands of consumers, retailers and regulators, Geoff says. "One of the key solutions is genetics... and we're really excited to be at the forefront of that within the New Zealand wine industry."

DRVs offer "huge opportunity" says viticultural consultant Dr David Jordan (DJ) describing their potential as "nothing short of phenomenal". On a recent Riversun research trip, Geoff and DJ saw first-hand how difficult it has become to grow grapes in Europe, with downy and powdery mildew, along with black rot, devastating crops that had been sprayed 20 times. Meanwhile, they saw neighbouring blocks of unsprayed and healthy DRV vines.

Some winemakers in Europe are choosing to only produce DRV derived wines, governments are embracing the
hybrid varieties, and DRV grapes have been officially approved as a blend option in Champagne. In August this year, United Kingdom supermarket chain Tesco launched Tesco Finest “Floreal”, with the hybrid variety name on the bottle. A Decanter review called it a “huge step”, offering “hats off ” to the supermarket, while wine writer Jamie Goode commended the “brave move”, reflecting on the potential of DRVs to “massively” reduce the carbon footprint of wine. “Tesco have taken a chance by leading the conversation.”

Growing resilience in New Zealand wine

Cloudy Bay Technical and Sustainable Development Director Jim White was introduced to the potential of DRVs by Cloudy Bay parent company Moet Hennessey in 2022, when he attended a conference in Italy with one of the breeding nurseries involved. “We were able to taste lots of wines for the first time and understand what was happening in this space in Europe.” The wine industry there is leaning into DRVs as it faces increasing pressure to reduce agricultural spraying, Jim says. “They knew that they weren’t going to be able to break that paradigm they found themselves in with diseases like powdery and downy mildew without going down a route of using plant genetics to introduce resistance.”

He has been working with Riversun on its import project for the past two years. Of the varieties planned for import, Sauvignon Nepis is the one he is most eager to see performing. Each new variety needs to be tested in New Zealand conditions, but his “gut feeling” is that Sauvignon Nepis will do well in Marlborough, offering the typicity expected of Sauvignon Blanc from the region, with a level of resistance that would require perhaps just quarter of the current spray programme. “For me it has the most similarities to Sauvignon Blanc and would be a great easy transition for use as either a blending component or as a standalone wine.”

New Zealand’s wine industry is in the “infancy” of understanding the potential here, says Jim, who spoke about DRVs at Bragato Research Institute’s 2024 Grape Days events. His review shone a light on the opportunities of what he calls a “revolution” in grapevine breeding, and on the widespread acceptance of DRV vines and wines in Europe. What will “really turn the dial” is when people see the vines performing in a New Zealand context and taste the wines they produce, he adds. “I think that’s when we’re going to see the significant upswing in interest – when we can get some liquid to lips.”

Many a slip twixt vine and lip

Geoff agrees DRVs are “hugely exciting”, but the process of bringing them into New Zealand is long and expensive, with plenty of potential pitfalls. One of those is the prevalence in Europe of a relatively new virus, grapevine Pinot Gris virus (GPGV), which can spread very quickly. New Zealand is one of the few countries that doesn’t have the virus, and Riversun needs to prove any material proposed for import is GPGV-free.

While Riversun was able to source some GPGV free DRV’s out of California and France, Sauvignon Nepis has had to be “cleaned up” in Italy, he says. This process can take years, but Riversun is hoping to receive ‘clean’ Nepis in February 2025, along with its second consignment of DRV’s. Most of the target varieties have been chosen for their disease resistance, abundant yield, and ability to partner with Sauvignon Blanc. But genetics is a “journey” and the hunt for better options will continue, Geoff says.

There’s another long road after the DRVs arrive, with the first group of imports in quarantine until December 2025, followed by a year of bulking up propagation material for grafting. All going to plan, vines for the first trial sites will hit the ground in late 2026, with commercial volumes available the following year.

Traits that appeal in Italy or France may not translate to New Zealand terroir, including characteristics in the wine, or resistance to the strains of powdery and downy mildew in vineyards here. To add further complication, resistance traits, which can be detected through DNA testing, can be derailed by susceptibility traits, Geoff says. They’re the proverbial bad apple in the breeding barrel and can see a DRV vine decimated by disease. “You can do a DNA test and go, ‘okay, some of the resistance genes are there’, but you still have to do the phenotypic work – that is, test them in vineyard conditions.”

Setting Riversun's sights on DRVs

Hybrids were not on the Riversun radar until August 2022, Geoff says, recalling the reputation for poor quality wines that saw them banned in Europe in the 1960s. But when Jim shared his excitement about the vines and wines he’d seen and tasted in Italy, and asked how to get them into the country, Geoff was intrigued by the pace of innovation in Europe. He began turning wheels to understand the “ecosystem” of DRV breeders around the world, contacting key players and developing relationships.

Between 2003 and 2009, Riversun imported 120 grapevine varieties and clones from around the world. Then the global financial crisis and ‘Sauvalanche’ hit and Riversun put the brakes on imports. However, the work initiated 20 years ago has been a key part of the new vision. “Genetics is a core part of our business,” Geoff says, explaining the importance of longstanding and trusted relationships between breeders and plant propagation licence holders. “They want to know that their materials are well protected by a trusted partner.”

Dr David Jordan

Mauro Negri, who worked at Riversun in Gisborne from 2013 then returned to his home in Italy during Covid-19, has become Riversun’s DRV expert in Europe, attending workshops, extending his understanding of developments in the genetic space, and building relationships with breeders, including Vivai Cooperativi Rauscedo in Northern Italy, and ENTAV in France.

Although busy setting up processes and exploring options, Riversun didn’t share its DRV plans until the Vision 40:40 event it hosted in February 2023 – looking back, and ahead, 40 years. That event included an announcement of the nursery’s plans and was followed by a call for industry support to help secure Ministry for Primary Industries (MPI) quarantine space.

The positive response, to Riversun and direct to MPI, was fuel to the import plans. Geoff and his wife Anna, a Riversun Director, travelled to Italy and Germany with Mauro in October 2023 to sign licensee agreements. Then in February 2024, Riversun ran a DRV tasting in Marlborough, with 10 key winemakers from major companies. Earlier this year Geoff and Anna returned to Europe to explore the DRV “revolution” with Mauro and DJ, along with Indevin Director of Winegrowing Patrick Materman.

They were “pretty shocked” to see the level of disease pressure they found, Geoff says, describing a warm, humid summer in northern Italy, akin to a hot house, where sprays were not doing enough to stop the spread of “unprecedented” downy mildew pressure. “Everyone you talked to said they had never seen it this bad before.” The picture was no prettier in Burgundy, where 30% of the canopy had been lost to downy mildew, “and they were lucky to have a 30% crop load”. He spoke to someone in the 10th generation of a family winemaking business who hadn’t seen anything like it in 50 years of wine growing. “This is climate change, and it’s having a massive impact in Europe. And yet, you go to these trial sites, and you see some of these DRVs looking as clean as a whistle.”

DJ and Patrick were tasked with providing a selection criteria for the research trip, with strong disease resistance to powdery and downy mildew at the top of the list. They both emphasise that growers will need to spray DRV vines a few strategic times every year, to reduce the risk of a mutation of the fungus developing and breaching the resistance.

The second target was Sauvignon Blanc compatibility. Because New Zealand’s industry is so heavily reliant on that flagship variety, DJ does not expect novel varieties to “shift the dial” on winemaking here. However, there’s potential to provide a “supporting act”, by bringing in “logical partners” for blending. The selection of DRVs is about playing to New Zealand’s strength, Patrick says. “Its international point of difference around pure aromatic intensity and fresh natural acidity.”

Patrick Materman

The third major target was that the vines had to have high and reliable yields, in recognition of the spiralling costs of growing wine. “One of the levers we can shift is yield,” Geoff says. They also want attributes like later ripening and higher acid. “In a world of climate change, where the vintages are starting earlier and becoming more compressed, having something which is later ripening and retains the acidity would be a real plus.”

Disease pressure is coming

New Zealand, and Marlborough in particular, has been spared many of the blows of climate change to date, thanks to a “Goldilocks window” in its geographic location, Geoff says. “But that won’t last… disease pressure is building.”

Patrick has had 35 years in New Zealand’s wine industry, and has seen spray rounds steadily increase over the past five to 10 years, particularly around powdery mildew in Marlborough, and downy mildew in the North Island. “Spray rounds have crept up from 10 to 15 rounds a season to 15 to 20 rounds.”

DRVs could significantly reduce spray use, cutting the environmental and financial cost of winegrowing, with fewer tractor passes, less labour, and a fraction of the agrichemical applications. Reducing spray requirements is ideal in the face of condensed and early vintages, and the need for pre-harvest spray intervals, Patrick adds. “My view is that you will get pretty solid buy-in from operations or vineyards wanting to reduce spray rounds and have varieties more resistant to disease pressure.” He expects the adoption of novel grape varieties for stand-alone wines to take longer. “That becomes a wider business decision with the need first to establish the consumer proposition.”

From a winemaking point of view, he’s excited to see and taste the results in New Zealand. He expects that some of the varieties they were impressed with in Italy and France will perform even better in New Zealand. “I am always trying to translate what they will taste like grown in New Zealand, and I think the flavours will be amplified.” Looking at genotype is one thing, but the proof is in the phenotype. “Getting them planted and seeing what particular attributes there are when grown in this place.”

Valentin Blattner

Swiss grape breeder Valentin Blattner bred a Cabernet Blanc when he was living in New Zealand in the late 1980s. The white disease resistant variety, a cross between Cabernet Sauvignon and resistant vines, is now recognised for its good growing characteristics and high fungal resistance, and is one of the leading DRVs in Europe. But in 1980s New Zealand, when hybrids were being pushed by a few passionate proponents (and shunned by many others) and Sauvignon Blanc was yet to truly hit its straps, little progress was made on Valentin’s dream. He instead returned to Europe, where he further developed that hybrid variety, and several others, says Riversun founder Geoff Thorpe, who met with the breeder on a recent research trip through Europe.