The rise of disease-resistant grapes in the UK

Viticulture is among the fastest growing sectors in UK agriculture and as the UK wine industry continues to grow, producers are increasingly turning to innovative solutions to combat the challenges of climate change, disease pressure, and sustainability.

One of the most promising developments in recent years has been the rise of PiWi grape varieties – a class of fungus-resistant hybrids that are reshaping vineyard management and winemaking across Europe and now, the UK.

What are PiWis?

PiWi is short for the German term Pilzwiderstandsfähig, meaning ‘fungus-resistant’. These varieties are the result of decades of careful breeding, typically crossing Vitis vinifera with disease-resistant American or Asian grape species. With the goal of creating vines that can withstand common fungal threats like downy mildew, powdery mildew, and botrytis, while still producing high-quality wines.

Rising popularity in the UK

In the UK, where we often have wet summers and high humidity, more traditional varieties can often be decimated during ripening and as we approach harvest. PiWi varieties have been purpose bred to combat these conditions and offer a sustainable, low-intervention solution showing remarkable resilience to these factors.

It is estimated that over 270,000 PiWi vines were planted in the UK during the 2023 season alone. In addition, wine growers are seeing less tending is required, reporting just 4–6 spray applications per season, compared to 10–12 for conventional varieties, significantly reducing both costs and environmental impact.

The advent of PiWis could be a game-changer –  particularly for organic and regenerative viticulture, traditionally thought of as near impossible in the UK climate where downy mildew has historically limited productivity. With fewer tractor passes required and limited spraying, the negative impacts of soil compaction are also reduced, aligning with regenerative farming principles.

Recent research and innovation

While PiWis are not new – some have been in development for over 30 years – their commercial potential is only now being fully realised. Recent trials in the UK and Europe have focused on winemaking potential, yield stability, and climate adaptability.

For example, Cabaret Noir (originally known as Cabernet Noir), a red PiWi with Cabernet Sauvignon parentage, has shown promise, producing clean fruit with excellent skin-to-pulp ratios.

Meanwhile, Voltis, now approved in Champagne under trial, is being explored for its early ripening and low susceptibility to botrytis, making it ideal for cooler climates like the UK and a possible great addition to the already exciting UK sparkling production.

Key PiWi varieties in the UK

Currently, some of the most commonly grown UK varieties include:

• Seyval Blanc – A white hybrid with a natural resistance to powdery and downy mildew. Seyval Blanc (pictured here) is well known for its crisp acidity, citrus and green apple notes with subtle floral hints. Works well blended into sparkling and still white wines and produces reliable yields. Currently the most widely planted in the UK, including at our Cotswold Hills Vineyard, where it contributes to an award-winning still white blend and a sparkling blend

• Solaris – A classic white variety, offering plenty of tropical fruit, peach, apricot, with higher sugar levels. Most commonly producing still whites or dessert wines. A high-yielding varietal with up to 12–15 tonnes/hectare in UK conditions. Solaris is generally early ripening making it ideal for the UK climate. Showing popularity among organic growers due to its low spray requirements

• Sauvignac – This white PiWi is a Sauvignon Blanc x Riesling hybrid with the aromatic, citrus, elderflower, and grassy notes to match. Used for both still whites and sparkling wines, it produces reliable yields. This is an increasingly popular grape with winemakers and consumers alike because of its Sauvignon Blanc-like character and suitability for sparkling wine production

• Cabaret Noir – A red PiWi with Cabernet Sauvignon parentage, you would expect to find blackcurrant, plum, and spice with some good tannin. Primarily producing reds and some rosé. Cabaret Noir is growing in popularity and getting some traction in the UK for its winemaking potential and disease resistance

• Divico – A Swiss origin red grape with deep colour, black fruit and firm, forward tannins. Divico produces high yields most often put into still red wines. It is particularly resistant to botrytis, making it ideal for wetter UK harvests like in 2024.

Cotswold Hills Vineyard at RAU

At the Royal Agricultural University’s Cotswold Hills Vineyard, we’ve embraced the PiWi movement with the planting of Seyval Blanc, which has proven to be a robust performer in the UK climate.

Seyval Blanc offers consistent yields and minimal disease pressure even in challenging seasons, making it a cornerstone of our sustainable viticulture strategy.

In contrast, our vineyard also grows Ortega, which – while well-suited to UK conditions – is not a PiWi variety. Ortega was bred in Germany in 1948 by crossing Müller-Thurgau with Siegerrebe, aiming to produce a grape with early ripening, high must weight, and aromatic intensity.

Unlike PiWis, which are bred specifically for fungal resistance by incorporating genetics from non-vinifera species, Ortega is a traditional hybrid within the Vitis vinifera lineage, focusing on wine quality and ripening characteristics rather than disease resistance. However, by ripening earlier, much of the mildew and botrytis issues we also face are mitigated naturally.

This distinction highlights two different philosophies in grape breeding:

• PiWi breeding – Integrating disease-resistant traits from wild grape species, resulting in vines that require fewer chemical inputs lending themselves to organic or low-intervention viticulture

• Traditional vinifera breeding – As seen with our Ortega, focusing on enhancing flavour, ripening time, and adaptability, often without the same level of disease resistance.

Despite not being a PiWi, Ortega remains a valuable variety for the UK climate. Its early ripening helps it avoid autumn rains, and its aromatic profile – often likened to Muscat or Gewürztraminer – makes it a favourite for still white wines. At Cotswold Hills, Ortega contributes to our award-winning white blend, offering floral notes and a soft texture that complements the crispness of Seyval Blanc.

Our vineyard, located on a south-facing slope near Down Ampney, on the Gloucestershire/Wiltshire border, serves as both a commercial operation and a living classroom for students. Every bottle of Cotswold Hills wine sold contributes to the RAU Enterprise Fund, helping students launch their own ventures in the agri-food and rural sectors.

Looking ahead

As the UK wine industry continues to evolve, PiWi varieties offer a compelling path forward – combining resilience, sustainability, and quality. While challenges remain in terms of consumer education and varietal familiarity, the momentum is growing at pace.

With yields generated of up to 12–15 tonnes per hectare in UK conditions – compared to lower averages for traditional grapes – PiWis are offering both economic and environmental advantages. These varieties are not only helping growers reduce their chemical inputs whilst delivering more consistent higher yields. Not only improving economic returns but also improving soil health, opening up new stylistic possibilities for UK wines.

For growers seeking to future-proof their vineyards, PiWis may well be the most exciting vines you’ve never heard of – until now.

ABOUT OUR EXPERT

Ryan Hanson is director of campus experience at the Royal Agricultural University, where he is responsible for a range of visitor functions including hospitality, accommodation, farms, equine, as well as gin, honey and wine production.

A seasoned restaurateur, Ryan previously worked at Aubergine in Chelsea and River Cottage HQ in Devon.

His work as a sommelier brought an Imbibe Hotel Restaurant Wine List of the Year Award and he was featured in the Hairy Bikers as part of his work with the University Vineyard and Cotswold Hills wine.

His career spans leadership and training in food and beverage, customer experience, and commercial strategy.

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