DISEASE RESISTANT GRAPEVINES FOR UK VINEYARDS

Research Report and Findings by Sam Middleton

Vine Grower of the Year 2019

Sponsored by VineWorks

This paper begins with an introduction of grape breeding, new varieties and their advantages. It then profiles four producers who were visited during the research, to show the different ways they have successfully made and sold wines from new varieties. They represent a range of styles and price points. The paper then profiles 11 new varieties, including information on aromas, resistance to fungal disease and observations on cultivation.

PURPOSE OF THE RESEARCH

The purpose of this research was to explore the potential of new grapevine varieties that have been bred for fungal resistance and the wines made from them. From a viticultural perspective, new varieties make a lot of sense: increased resistance to fungal diseases mean significantly fewer spray applications and associated costs. Some varieties offer higher yields than Vitis vinifera with earlier ripening and less loss to disease. However, the two or three examples of wines made from these varieties that I tasted while studying at Plumpton College left me unconvinced. This project offered the opportunity to develop a greater understanding of how these varieties are performing in commercial vineyards and, equally importantly, their potential in the winery. Funding from VineWorks supported research trips to:

• Switzerland: to visit grape breeders to learn about the process of breeding new varieties
• Germany: to visit a vine nursery to learn about the propagation and supply of grapevines 
• Belgium and the Netherlands: to visit wine regions with similar climatic conditions to England

All three trips enabled me to visit a range of inspiring wine producers, representing different price points, viticultural approaches, and winemaking styles. 

INTRODUCTION

Wine is often synonymous with tradition. Estates passed down through generations. Historical cellars. Long-established techniques and philosophies. But there is also a current of evolution: the emergence of new wine regions such as England; the “rediscovery” and increasing popularity of one of the oldest wine styles, orange wine; and advancements in modern oenological equipment and vineyard mechanisation. Tradition, innovation, and of course, human agency.

Grapevines are no different. A widely cited 2011 academic paper concluded from DNA analyses that humans have been breeding and mixing grape varieties for at least 8,000 years. In the late 19th century phylloxera devastated the wine industry, until the human intervention of grafting the vulnerable Vitis vinifera onto American rootstock secured its survival. The new varieties discussed in this booklet form part of this tradition. They are not made in laboratories or through genetic modification, but through careful, time-consuming manipulation of grape vine pollination by hand; an old technique complemented by modern genetic analysis to evaluate its success.

Grapevine pollination

BREEDING NEW VARIETIES Grapevines are self-pollinating, having both female and male sexual organs.  Breeding new grapevine varieties requires the crossing of two “parent” grape vines.  Pollen is collected from the male parts (stamens) of one grapevine parent.  The stamens of the inflorescences of the other grapevine are removed by hand, and the pollen from the “male” parent spread onto the inflorescences of the “female” parent and the entire inflorescence wrapped in a numbered protective bag (see photo). It matters which parent is the male and which the female: Divico (red variety) and Divona (white variety) have the same parents, but the former has a red variety as its “female” parent, while the latter’s “female” parent is a white variety. Fertilised flowers form berries, the seeds of which are extracted once the berries are fully ripened. Seeds are tested, and when approved, planted out, to germinate as a new variety.

The new varieties in this booklet are referred to by some as PiWis, short for PilzWiderstandsfähig, a German term roughly translated as fungal-resistant. In the United States they are referred to as Hybrid varieties, while in France they are termed resistant varieties. Others prefer to use the term “new varieties,” citing marketing considerations and the fact that while the current focus of breeding is on resistance to fungal disease, investigations are already beginning into early/late ripening, acidity retention and mitigation of spring frosts. Research and trials are underway across Europe and the United States, and the number of new varieties available for planting - already substantial - are only set to increase. 

THE ADVANTAGES OF NEW VARIETIES 

The current focus of new varieties is resistance to Botrytis (Botrytis cinerea), Downy Mildew (Plasmopara viticola) and Powdery Mildew (Uncinula neactor). The need to protect Vitis vinifera from these fungi is a key reason why viticulture in Europe accounts for 15% of pesticide use, despite representing just 3.5% of agricultural land. 

England has a challenging climate for wine production with long growing seasons and high fungal disease pressure in most years. Protecting grapes from fungal infection represents a significant cost, financially and environmentally. If following the WineGB Plant Protection Products Green Book, a typical spray programme in England in 2022 might involve 14 applications. To follow this fungicide spray programme might cost approximately £2-3,000 per hectare for the products. If products are not applied using in-house equipment including a tractor, plus fuel and staff time, the cost of application (excluding the chemicals) could - if using a contractor - run to approximately £6,000 per hectare. In addition to these financial costs are the associated soil compaction from the tractor, CO2 emissions and the indirect impact of pesticides on biodiversity and beneficials. 

The breeders of new varieties recommend one to five fungicide applications per year, depending on variety and disease pressure. For varieties with the strongest resistance, one or two applications are still recommended, to reduce the risk of fungi genetically mutating and overcoming the grapevine’s resistance. However, this research has found commercial vineyards in the Netherlands and Switzerland that are successfully growing some new varieties for over five years with zero fungicide applications, and there are no doubt others.

Given these advantages, it is no surprise that plantings of new varieties have increased in both new (Northern European) wine regions such as the Netherlands, Belgium and Sweden, and old world wine regions: in Switzerland they have increased by 412% in the two decades up to 2022, and now cover 410 hectares, representing 2.8% of all plantings. In Germany, between 2017 and 2021 the number of hectares planted with new varieties increased by 355% to 507 in total. In France, the Champagne region is set to approve the commercial planting of the new variety Voltis, which will, for an initial five years, be permitted to comprise up to 5% of cultivated land and 10% of a blend. Trials by the research body INRA found that some experimental Champagnes containing a small amount of Voltis scored better than traditional Champagnes in blind tastings conducted with regional wine organisations.

England is no different. In 2016 VineWorks planted 2,000 vines of new varieties. By 2022 that figure had risen to a cumulative total of 127,700 (multiple new varieties), including 46,450 in 2022. 80,000+ are scheduled for 2023. According to WineGB, Seyval and Solaris (two of the oldest varieties bred for fungal resistance) are the fifth and sixth most planted grape varieties in England and Wales, representing 117 and 93 hectares respectively, and 3% and 2.5% of all plantings (hectares) respectively. 

Table 1: The most popular new varieties planted since 2000 (varieties for England reflect vines planted by VineWorks only)

Country	Most popular new varieties 2020-22 (by vines planted)
England & Wales	Seyval blanc, Solaris, Cabaret noir, Sauvignac
Germany	Souvignier gris, Cabernet Blanc, Muscaris
Switzerland	Divico, Solaris, Cabernet jura

PROFILE OF WINE PRODUCERS VISITED 

The two principal concerns regarding wines made from new varieties relate to their quality and the perceived challenge of selling them. The following selection of producers - representing a range of price points and styles - were visited as part of this project, but there are many more examples of successful wines made from new varieties, including a growing number in the United States, such as Vermont-based La Garagista, which so impressed New York Times’ wine critic Eric Asimov. 

These producers have all found success marketing their wines; frequently emphasising the sustainable credentials of the grapes, sometimes downplaying the varieties and focusing on the wine, sometimes drawing comparisons with similar tasting, well known varieties and styles and sometimes placing the grapes front and centre. The common thread is that they are reaching their target audience and telling them a compelling story.

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WIJNGAARD DASSEMUS

Ron and Monique set out from the start to avoid spraying any chemical products. This philosophy, combined with the humid Dutch climate, took them down the path of exploring new varieties and there has been a lot of experimentation: 25 trialled in total. The vineyard and surrounding land is planted with beneficial herbs, plants and trees to support the vines and nurture biodiversity, and animals also feature. Their popular “wild wine” range is exported as far afield as Japan and includes an orange wine produced in partnership with wine writer Simon J Woolf. 

Wines: ~ €14

www.dassemus.nl

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MINZEVEN

The name MinZeven refers to the fact that this vineyard lies seven metres below sea level on land reclaimed in the 20th century. Sylvia weaves a compelling story of her search for the perfect new varieties for her chemical-free site, where enhancing biodiversity and working with nature are the guiding principles. She crafts exclusive limited edition sparkling wines in the traditional method that capture the heritage of their special terroir, using yeasts she has had isolated from her vineyard. Sales are direct to consumers who are located throughout Europe.

Wines: €50-€70

https:/minzeven.com/en/ 

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WIJNGOED WOLF

Winemakers Bas and Laura honed their craft in France, and it shows in their wines (Johanniter, Souvignier Gris and Sauvignac), which are accomplished, familiar, and crowd-pleasing. Their winemaking story focuses on their vineyard soils and unique climate (for the Netherlands), and their approach to vineyard management which seeks to enhance biodiversity.

Wines:  ~ €14.50

www.wijngoedwolf.nl

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WIJNGAARD ST. MARTINUS

The largest wine producer in the Netherlands (28 hectares), owner and winemaker Stan Beurskens embraced new varieties as an environmentally and financially sustainable option. St. Martinus produces a wide range of award-winning wines from sparkling through to white, red and rosé. It has a thriving wine tourism business, offering tastings, vineyard visits, open days, and opportunities to get involved. Stan finds that likening wines made from new varieties to similar tasting, better known Vitis vinifera, is a useful way of introducing consumers to his wines. 

Wines: €18-60

https://wijngaardmartinus.nl/

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CASANOVA WEINPUR

A multi-award-winning organic producer based in Walenstädt, Switzerland. The main offering is a range of elegant, refined Pinot noirs, but the Cabernet Jura - grown on the banks of Walensee and made using a similar approach of spontaneous fermentation in old oak foudres, with gentle cap management - has won critical praise. Marco Casanova sees nature playing a pivotal role in the vineyard, where he seeks to promote biodiversity and create wines that reflect the elegance and beauty of their terroir.

Wines (Cabaret Jura): €30

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PROFILE OF NEW VARIETIES 

The following section features 11 new varieties, including information on aromatic profile, resistance to fungal disease and observations on cultivation.

The primary flavours section is intended only as a general indication of the grape’s aromatic profile, based on sampling a number of wines at wine fairs, organised tastings and visits to producers. It is not definitive. Likewise, the cultivation section is only a general indication of what might be expected when growing these new varieties in England. 

The scores for resistance are between 1 (+) and 3 (+++), and are an estimate based on a combination of information from grape breeders, vine nurseries, and visits to commercial wine producers in the Netherlands and Switzerland. 

SCORES FOR RESISTANCE DEFINITION Please note: This scale would not be appropriate for Vitis vinifera. For example, Divico scores 1(+) for Powdery mildew resistance: it requires two spray applications, especially in high disease years. However, in a trial plot in Switzerland in a year of high disease pressure and no fungicide sprays, on average approximately 5% of each Divico vine was affected by Powdery mildew, while almost 100% of the Vitis vinifera vines growing beside them were affected.

1 (+) Vulnerable to these fungi and between two and five fungicide applications are necessary.

2 (++) Some vulnerability has been noted and two fungicide applications are strongly recommended (in some cases, required) at the key times: once post-bloom (E-L Stage 27), once at pea-size (E-L Stage 31) and in years of high disease pressure, potentially pre-bloom (pre E-L Stage 19); or there were no examples found during this research of the variety being grown commercially with zero fungicide applications for more than three years.

3 (+++) In more than one commercial vineyard the variety has displayed strong resistance for at least three years with no fungicide treatment.  Vine breeders recommend that even those varieties rated 3 (+++) should be sprayed twice a year as a precaution (E-L Stages 27 and 31).

Table 2: Profile of new varieties 

Variety	Pinotin (red)
Primary Flavours	Blackcurrant, blackberry, plum, dark cherry, green bell pepper
Description	Heavy dark fruits on the nose can imply a bold wine, but it is light on the palate, and often oak is used to provide structure and secondary aromas.
Resistance Rating	Powdery mildew ++       Downy mildew +      Botrytis +
Resistance	Requires spray applications. Moderate resistance, but vulnerable to Downy mildew and thin grape skins can increase likelihood of pest damage and subsequent Botrytis and volatile acidity (VA).
Cultivation	Reports of later budburst. Moderate growth, mostly upright. Can produce higher yields. In England ripening appears to be similar to or slightly earlier than Chardonnay if similarly loaded, but this would likely require crop thinning. Acidity levels tend to be lower than Chardonnay.
Variety	Cabaret noir (red)
Primary flavours	Blackcurrant, red cherry, raspberry, green bell pepper
Description	Examples range from very dark fruits through to lighter raspberry and wild strawberry. Green bell pepper frequently present. Savoury notes in some examples.
Resistance rating	Powdery mildew +    Downy mildew +    Botrytis ++
Resistance	Thick berry skins boost resistance to Botrytis. Spray applications (up to five) required in high disease years.
Cultivation	Upright, medium to strong growth. Lower yielding than other varieties. Early ripening.
Variety	Cabernet jura (red)
Primary flavours	Blackberry, dark cherry, plum, kola nut, tomato leaf
Description	Examples range from dark cherries and blackberries to lighter - almost confected - red fruits and kola nuts. A hint of tomato leaf can be found in the heavier examples.
Resistance rating	Powdery mildew ++    Downy mildew +++    Botrytis +++
Resistance	Good resistance against Downy mildew and Botrytis. Some vulnerability to Powdery mildew.
Cultivation	Upright growth. Medium ripening. Can produce high yields.
Variety	Divico (red)
Primary flavours	Blackcurrant, dark cherry, raspberry, cranberry, red cherry
Description	Examples range from dark blackcurrant bordering on cassis, with dark cherries, through to lighter raspberry and cranberry.
Resistance rating	Powdery mildew ++    Downy mildew ++    Botrytis ++
Resistance	Most vulnerable to Powdery mildew, which can occur if canopy ventilation is poor. No examples found of how it fares with no fungicide applications for more than three years.
Cultivation	Upright, medium to strong growth. Although budburst and flowering tend to be early, ripening is late as achieving phenolic ripeness can require longer hang-time.
Variety	Souvignier gris (white)
Primary flavours	Lime, grapefruit, green bell pepper, pineapple, mango
Description	A versatile grape, making light crisp citrus-driven wines with hints of grapefruit and gooseberry, through to more tropical and perfumed offerings featuring lychee, pineapple, and mango. Also used to produce sparkling wines and Orange (skin-contact) wines.
Resistance rating	Powdery mildew +++    Downy mildew ++  Botrytis +++
Resistance	Demonstrated strong resistance in one vineyard over four years with no fungicide applications, but in another site required two applications against Downy mildew.
Cultivation	Upright, vigorous growth. Medium to late ripening. Resistance allows longer hang-times.
Variety	Sauvignac (white)
Primary flavours	Lemon, grapefruit, passion fruit, gooseberry, green bell pepper
Description	Most examples are citrus-driven wines. Those picked later display more tropical notes, including apricot, mango, and pineapple. Herbaceous notes, sometimes of green bell pepper, sometimes tomato leaf, and cut grass are present in many examples.
Resistance rating	Powdery mildew +++    Downy mildew +++    Botrytis ++
Resistance	Strong resistance widely reported, but two cases of Botrytis rot of bunches at harvest noted.
Cultivation	Moderate yields. Tendency to flop rather than upright growth. Later ripening. In Switzerland, reported to ripen just before Pinot noir.
Variety	Cabernet blanc (white)
Primary flavours	Lime, grapefruit, green bell pepper, gooseberry, cut grass
Description	Many examples are reminiscent of New Zealand Sauvignon blanc, sometimes with a honeyed edge to the citrus-herbaceous profile.
Resistance rating	Powdery mildew ++    Downy mildew +    Botrytis ++
Resistance	Most vulnerable to Downy, requiring up to five fungicide applications in high disease years. Less resistant than Souvignier gris and Sauvignac grown in the same vineyard.
Cultivation	Vigorous, upright growth. Low fruit set observed in some vineyards in the Netherlands. Mid to late harvest, and in wet years acidity can remain high.
Variety	Solaris (white)
Primary flavours	Elderflower, peach, apricot, banana, pineapple
Description	Most examples were produced as dessert wines, displaying tropical aromas. Wines that were made from grapes picked earlier tended to display notes of elderflower and peaches.
Resistance rating	Powdery mildew +++    Downy mildew +++    Botrytis ++
Resistance	Displays strong resistance in multiple vineyards with no fungicide applications. Botrytis is a potential issue, and early ripening can lead to wasp damage and further incidence of Botrytis.
Cultivation	Can be difficult to train as shoots do not all grow upright. High yielding, even in poor years. Early ripening. Acids can fall quickly during the harvest window.
Variety	Divona (white)
Primary flavours	Citrus, floral, honeysuckle, melon
Description	Some examples can display herbaceous, white pepper and mineral notes, while others display a Gewurztraminer-like perfume with rose petal at the fore.
Resistance rating	Powdery mildew ++ Downy mildew ++ Botrytis ++
Resistance	No fungicide sprays required in a commercial vineyard in Switzerland during the challenging 2021 vintage, but this is a newly released variety (2018), so further corroboration is needed. Therefore a rating of 3 (+++) is not awarded at this point. The grape breeders recommend between one and three applications per year.
Cultivation	Upright, medium to strong growth. Early ripening, like Müller-Thurgau. Medium to high yield but may require crop thinning. Medium growth, tendency of shoots to flop.
Variety	Voltis (white)
Primary flavours	Citrus, floral, green apple
Description	Developed to act as a junior blending partner in Champagne, the aromatic profile of Voltis base wines tends to be described as relatively neutral.
Resistance rating	Powdery mildew ++ Downy mildew ++ Botrytis ++
Resistance	Strong resistance to Powdery mildew in trials with no fungicide application. Some vulnerability to Downy mildew. The grape breeders note a sensitivity to Black Rot and recommend two applications against black rot together with fungicides as a precaution. This research found no examples of commercial vineyards growing Voltis with zero fungicide treatments, therefore a rating of 3 (+++) is not awarded at this point.
Cultivation	Budburst approximately five days after Chardonnay grown at the same site. Ripening window like Chardonnay but can be later (especially if budburst is considerably later). Upright growth. Cane pruning is recommended, as base buds tend to display low fruitfulness.
Variety	Floreal (white)
Primary flavours	Lime, green apple, passion fruit, gooseberry, peach
Description	Trialled in the Loire Valley, Floreal wines are described as aromatic, displaying a range of aromas from exotic to hedgerow, and draw comparisons with Sauvignon blanc.
Resistance rating	Powdery mildew ++ Downy mildew ++ Botrytis ++
Resistance	Strong resistance to Powdery mildew in trials with no fungicide application. Some vulnerability to Downy mildew. Some sensitivity to Black Rot with  recommendation of one or two applications against black rot as a precaution in years with high disease pressure. This research found no examples of commercial vineyards growing Floreal with zero fungicide treatments for more than three years: therefore 3 (+++) is not awarded at this point.
Cultivation	Vigorous growth, sometimes not upright. Higher yielding than Chardonnay, but later ripening.

CONCLUSION

Support from VineWorks enabled me to deepen my knowledge of grape breeding and propagation and see first-hand how new varieties were performing in commercial vineyards, in climates that bore some similarity with England. The cost savings as a result of fewer fungicide applications were dramatic. Moreover, for every producer that I visited, new varieties were chosen not only to reduce input costs, but as a way to enable them to nurture and enhance biodiversity in and around their vineyard.

What I found during this research was that new varieties were being used in a range of different ways. Some growers put the grape front and centre when talking with customers; others likened the wine/grape(s) to a more familiar 100% Vitis vinifera. There appears to be a slightly different approach in Champagne - at least for the moment - in which new varieties will serve as a background or “silent” blending partner, to mitigate climate change, offer more reliable yields and reduce costs. The option of blending 100% Vitis vinifera with new varieties is something that has perhaps been underexplored to date, with relatively few commercially available examples, but it would appear to offer considerable potential.
 
These are early days for new varieties and what comes next is impossible to predict. However, with climate change, rising costs of fungicides, and a widely held view that pesticide use should be reduced, and biodiversity supported, it is difficult not to see a place for them in the wine world of the future.

ABOUT THE VINE GROWER OF THE YEAR AWARD

The Vine Grower of the Year award is granted to an individual for a UK-based research project which will advance the understanding of viticulture in this country. This exciting award provides the candidate with £2,000, which was generously donated by VineWorks, to enable them to carry out a study tour to an overseas wine producing region to bring back new ideas and skills useful to UK growers. 

2019 WINNER – SAM MIDDLETON 

Sam Middleton works in the vineyard at Black Chalk Estate in Hampshire. He previously worked in public policy before retraining in Viticulture & Oenology at Plumpton College. In his final year at Plumpton, he was awarded the Vine Grower of the Year grant to undertake research to benefit the English wine industry. Sam now works for VineWorks as a Viticulturist. 

ACKNOWLEDGEMENTS

I would like to thank the team at VineWorks - James Dodson, Chris Buckley, and Will Mower - for backing this project, as well as providing advice and support. A very special thanks to viticulturist, Sam Doncaster, who generously shared a considerable amount of his time and knowledge. Thank you to Peetra van der Knaap, a wine expert who recommended and facilitated visits with producers in the Netherlands, Volker Freytag and Friederike Klein of vine nursery Rebschule Freytag, grape breeders Spring Jean-Laurent (Agroscope) and Valentin Blattner, and Martin Vickers of Halfpenny Green. Finally, a thank you to all the wine producers who took the time to show me their vineyards and wineries and talk through their wines and experiences with new varieties.