piwis the way forward for British Are viticulture?

Plantings of piwi varieties that offer fungal resistance are on the rise – with environmental sustainability being a key driver. But are they worth investing in, what kind of wines do they make, and will consumers buy them? British growers shared their views on the pros and cons at the recent Vineyard & Winery Show. Deputy editor Sarah Kidby reports

Viticulture in Europe accounts for 15% of pesticide use, largely fungicides, despite making up only 3.5% of agricultural land. With long growing seasons and high fungal disease pressure in most years, a typical spray programme in England last year might have involved around 14 applications. Breeders of piwis, also known as new or hybrid varieties, recommend just 1-5 sprays depending on the variety, said grower Sam Middleton, who recently visited growers, breeders and vine nurseries in Switzerland, Germany, Belgium and The Netherlands as part of a Vineworks research project. Some commercial vineyards in Switzerland and The Netherlands had been growing new varieties for over ve years with no fungicide applications at all.

Piwis are the result of cross breeding, with a current focus on developing varieties that are resistant to fungal disease, particularly botrytis, downy mildew and powdery mildew. Investigations are also underway into early/late ripening, acidity retention and mitigation against spring frosts. Vineworks planted over 46,000 vines of new varieties in England in 2022, bringing the cumulative total planted by Vineworks alone to 127,700 – compared to just 2,000 in 2016 – and it plans to plant a further 80,000 plus vines in 2023. The most popular varieties planted since 2000 in England (by Vineworks) and Wales are: Seyval, Solaris, Caberet Noir and Sauvignac.

Pros and cons

While some say new varieties could o er at least a partial solution to the environmental and nancial cost of fungicide applications, a number of delegates in the audience questioned how the research ndings translate to the UK.

Doubts were raised as to whether UK growers will ever be able to do only 1-2 sprays. One researcher in the audience suggested at least four applications would be required due to the UK climate. Additionally, whilst reductions in fungicide costs may be achieved, it’s worth bearing in mind that the cost of initial establishment will be higher, as new varieties tend to cost 30-40% more per vine than traditional varieties, mainly due to the cost of licensing, according to Mr Middleton’s report for Vineworks. Although the varieties do not o er a miracle x, they could o er a way to grow vines in a more sustainable way, one grower said.

On starting his research, Mr Middleton said his main questions were what kind of wines these varieties make, do consumers buy them, and for what price. Having visited a wide range of producers, he saw some wines that convinced him of the value of piwis. In England, the 2022 harvest saw Caberet Noir fetching a similar range of prices per tonne as Vitis vinifera. When it came to selling the wines however, all successful producers had one thing in common – a compelling story about their business which they communicated e ectively with consumers. Mr Middleton summed up: “These are new varieties that do not have the body of winemaking knowledge behind them, which is a challenge. But I think there is huge potential for experimentation and innovation, especially in this country.”

Martin Fowke, head winemaker at Three Choirs Vineyards, questioned how long the fungal resistance qualities o ered by piwis will last before the pathogens evolve – pointing out that the risks in vineyards don’t stay still, so piwis may not o er a complete answer. “I’m not saying don’t plant them, but don’t go in with your eyes closed,” he said. Whilst piwis could provide a head start on fungal resistance, for those who are not able or willing to plant new varieties, focusing on soil health and balance and keeping existing vines healthy will naturally create more disease resistance, he added.

Gusbourne vineyard manager Jon Pollard, who was also on the panel at the event, currently grows Pinot Noir, Chardonnay and Pinot Menerie in Kent and Sussex. Although ying the ag for noble varieties, Mr Pollard said he expects the vineyard will at some point in the future “dip a toe in the water” when it comes to planting piwi varieties – describing them as “a really interesting alternative coming into the industry, adding to the palate of English wine”. However, he believes winemaking with new varieties may require di erent ways of thinking to get the best out of them – and more work is needed to nd out their individual attributes.

Speakers were agreed that knowing what you want to achieve and what your target market is before you plant is key for choosing the right variety – rather than planting rst and planning later. Although piwi varieties are achieving success in Europe and the US, Mr Middleton concluded that “it will really require people to dip their toe in by experimenting to see how they perform in this country and what kind of wines you can make. With the challenge of climate change, I think there’s a place for [piwis] alongside the [noble] varieties.” this variety, but ripening is late, as achieving phenolic ripeness can require longer hang-time. It was given scores of 2 for powdery mildew, downy mildew and botrytis resistance.

Voltis

Colour: White (sparkling)

Origin: Villaris x MTP 3159-2-12

Voltis was developed to act as a blending partner in Champagne. The aromatic pro le of its base wines tends to be described in relatively neutral terms; emulating Chardonnay, with hints of citrus and green apple, according to avour pro les published in Sam Middleton’s report for Vineworks. It has recently been approved for commercial planting in the Champagne region up to 5% of cultivated land or 10% of the blend over a period of ve years.

Trials have shown strong resistance to powdery mildew with no fungicide application, but some vulnerability to downy mildew. Grape breeders have noted a sensitivity to black rot and therefore recommend two applications against black rot together with fungicides as a precaution. Voltis was only approved for commercial planting in 2022, and therefore currently lacks a track record in commercial vineyards.

Bud burst was approximately ve days after Chardonnay growth at the same site, while the ripening window is similar to Chardonnay but can be later – particularly if bud burst is considerably later. Cane pruning is recommended as base buds tend to display low fruitfulness. It was given resistance scores of 2 for powdery mildew, downy mildew and botrytis, indicating some vulnerability has been noted and two fungicide applications are strongly recommended or required (once post-bloom, again at pea-size and in years of high disease pressure, potentially pre-bloom).

Divico

Colour: Red

Origin: Gamaret x Bronner

Examples of wines range from dark blackcurrant bordering on cassis, with dark cherries, through to lighter raspberry and cranberry, according to Sam’s report for Vineworks. This Swiss-developed variety is thought to be a potential game-changer for English red wine production as it fares well in the UK climate.

It is most vulnerable to powdery mildew, which can occur if the canopy ventilation is poor. Mr Middleton found no examples of how it performs with no fungicide application over more than three years.

Medium to strong growth was reported. Bud burst and owering tend to be early with

Souvignier Gris

Colour: White

Origin: Seyval Blanc x Zähringer

This is a versatile grape which makes light, crisp, citrus-driven wines, with hints of grapefruit and gooseberry, through to more tropical and perfumed o erings, featuring lychee, pineapple and mango, according to Mr Middleton. It can also be used to make sparkling wines and orange (skin-contact) wines.

This variety demonstrated strong resistance in one vineyard over four years, with no fungicide applications – but on another site required two applications to protect against downy mildew.

It has upright vigorous growth with medium to late ripening and resistance allows longer hang times. It scored 2 on downy mildew resistance and 3 for powdery mildew and botrytis, meaning that it displayed strong resistance for at least three years with no fungicide treatment in more than one commercial vineyard. Vine breeders recommend varieties with a score of 3 should be sprayed twice a year as a precaution (at E-L stages 27 and 31).