The vines that could upend the wine world

PIWIs, or fungus-resistant grapes, are emerging as an alternative to classic grape varieties. But they’re not problem free. Simon Woolf explores the issues.

Thomas Niedermayr; José Vouillamoz
Thomas Niedermayr; José Vouillamoz

At first glance, youthful Thomas Niedermayr fits the profile of many natural winemakers. He’s passionate about organic farming, ferments only with wild yeasts, doesn’t filter his wines and works with the minimum possible added sulphites.

But visitors to the Niedermayr estate in northern Italy’s Alto Adige region may be surprised by what’s in his vineyards. There are none of the obsessions that usually go hand in hand with natural wine: no ancestral grape varieties being reintroduced, no precious old vines or ungrafted plots. Instead Niedermayr farms only modern disease-resistant crossings such as Solaris, Souvignier Gris and Bronner. Why has he forsaken the region’s long-established Burgundy varieties, or Gewürztraminer or its indigenous Vernatsch or Lagrein?

The emergence of PIWIs

Niedermayr’s father Rudi converted the family farm to organic cultivation in the 1980s and started making wine from 1993. “My father wanted to work with nature, not against it,” explains Niedermayr, “but he noted that with traditional varieties like Weissburgunder, you have to reckon on 14 or 15 vineyard treatments [of copper and sulphur] a year.”

As each treatment increases petrol usage and CO2 emissions, and each passage through the vines further compresses the soil, “this couldn’t be the future for us in organic cultivation,” says Niedermayr. His father planted experimental plots of two hybrids, Marechal Foch and Regent, in 1993, and the results were instantly gratifying — treatments could be reduced to either nothing in a good year, or a maximum of two or three sprays in a year with more adverse weather conditions.

The Niedermayrs grubbed up their last conventional plot — the aforementioned Weissburgunder — in 2019, and now farm 100 percent disease-resistant varieties. Once called “direct producers” or hybrids, such varieties have been bred since the 1890s, when the race was on to find alternatives that could resist the encroaching scourges of powdery mildew and phylloxera. Usually defined as inter-specific crossings, grape hybrids are crossings between two Vitis subgenuses, as for example with Clinton: Vitis riparia Michaux crossed with Vitis labrusca Linne.

As many of the first attempts at such crossings (Clinton, Noah) included resistant American varieties from various Vitis species from North America, the results often displayed a typical “foxy” aroma and rapidly garnered a poor reputation. Leading grape geneticist José Vouillamoz adds that some of these early man-made crossings could even produce poisonous methanol alcohol when fermented.

Yet research has continued, especially in German wine institutes such as Geisenheim and the Staatliches Weinbauinstitut Freiburg, with the focus shifting to the creation of crossings suitable for cooler or wetter climates where traditional varieties struggle. The German term PIWI has gained currency: standing for the typically Teutonic mouthful pilzwiderstandsfähige Rebsorten, it translates to “fungus resistant grape varieties” and was coined partly to avoid the negative connotations of the word hybrid.
Confusion between the terms hybrid and PIWI is rife, with many wine professionals using them interchangeably. Importantly, the European Union forbids the use of hybrids in the production of quality wine — a situation that has vexed English winemakers with Seyval Blanc and other PIWIs in their vineyards (although confusingly, PIWIs can be used for the 'Quality Sparkling Wine' category).

This has resulted in what Swiss biologist José Vouillamoz describes as “decisions made for economic purposes rather than scientific purposes”, where newer generations of PIWIs have been classified as Vitis vinifera and thus allowed in quality wine production. Varieties such as Solaris, Muscaris or Cabernet Cortis are the result of extremely complex, multi-generational crossings, often involving more than 50 parent varieties. While not 100 percent Vitis vinifera, they are hard to classify otherwise. The campaigning organisation PIWI International offers this fudge of a definition: “New cultures, which have been grown after 1950, are very complex, may have been created with Asian varietals and are the result of decades of crossings. They belong to the type Vitis vinifera because they are not to be distinguished taxonomically.”

Vouillamoz, who lives in the Swiss Valais wine region, acknowledges “hybrids have a right to exist. There is a niche market for them.” However, he adds: “I’ve tasted many wines made from hybrids. Some were undrinkable, some were good. None of them was as complex or as deep as the traditional varieties I know.” He also points out that, thus far, the vineyard surface planted with hybris or PIWIs worldwide is minuscule — certainly less than 5 percent of the world’s total plantings. “It has not revolutionised the wine world,” he says. “We will always want to stick with Pinot Noir at Domaine de la Romanée-Conti. I could never imagine Regent being planted in Barolo to replace Nebbiolo.”

For and against

Vouillamoz’s views are echoed among many wine professionals. Can PIWIs really deliver when it comes to fine wine quality? 

For a growing band of enthusiasts, including the Niedermayrs, it’s perfectly possible. Manuel Ploder, of the Demeter-certified Ploder-Rosenberg winery in Styria, Austria, is another believer. The Ploder-Rosenbergs started planting PIWI varieties in 2005, one year before they began working with biodynamic viticulture.

Ploder admits that their first planting, Regent, ultimately proved to be unsuccessful. “We didn’t like the taste,” he explains. “Like many second-generation hybrids, it has a hole in the palate.” The Regent was ripped out, but now the family grows Souvignier Gris, Muscaris, Bronner, Sauvignac, Blutenmuskateller, Solaris and Terrason, which together represent about 60 percent of their vineyard, 11.5 ha in total. Commenting about negative opinions in the industry, Ploder says : “I hear those voices of course. Colleagues say there’s no finish, and it’s not transporting the terroir, but I think that’s sometimes due to the age of the vines.” He also points out that it takes time to understand the character of new PIWI varieties: “The winemaker needs to see them as authentic varieties, not copies of something else.”

Recent bottlings from Ploder-Rosenberg and Thomas Niedermayr might just sway the likes of Vouillamoz and other detractors. Both properties have made outstanding wines from the pink-skinned Souvignier Gris — as a varietal at Niedermayr and in blends at Ploder-Rosenberg. Ron Langeveld, an organically certified winemaker based near Breda in the Netherlands, is also a fan of the variety. His vineyards are 100 percent planted with PIWIs.

Langeveld did not come from a winemaking background but, after considerable research, felt that “growing PIWIs is the logical choice for our Dutch climate, especially if you want to work organically”. Langeveld has spent 15 years experimenting with successive generations of PIWIs and selecting the best performers: “After four to five years we noticed infections in some varieties, especially in very wet years. Other varieties had no problems in these years and we slowly replaced the weaker varieties.” He’s tried a total of 24 cultivars and has honed in on 13, based on wine quality as well as resistance.

Langeveld has never sprayed anything on his vineyards, not even copper or sulphur — pruning is the only routine activity. He’s steadfast in his choice and vastly prefers to work with PIWIs than to deal with endless treatments or vineyard diseases. His achievements with Solaris and Souvignier Gris, in particular, are encouraging.
If there’s a common thread, those growers who become enthused with PIWIs are often working organically or biodynamically; Miha Batič in Slovenia is another example. Increasingly, PIWIs are gaining traction in the natural wine world too. But isn’t there a certain irony about minimal interventionists choosing highly bred and thus “man-made” grape varieties?

The gene question

Both Thomas Niedermayr and Manuel Ploder say they are anti-genetic modification and GMOs (genetically modified organism). For Niedermayr, the line is between crossings versus “plants that are created in the laboratory by means of gene manipulation”. But Vouillamoz points out that it is difficult to make any such distinction. Commenting on inter-specific crossings, he muses: “If I take species that are not supposed to have sex together, and I make them have sex, I’ve created a genetically modified organism. For a biologist, this is like creating a mule from a donkey and a horse, and this can be considered GMO.”

As grape breeding of newer PIWI generations becomes more sophisticated and more precisely controlled, it may throw up difficult questions for those growers who are against intervention in any aspect of their production. The latest PIWI varieties, created in 2018, have moved from having monogenic resistance — where a single resistant gene is isolated via successive crossings — to polygenic resistance, where two or three resistant genes are isolated to ensure that a variety can withstand pathogens which mutate. While this stops short of genetic modification, the modern technique of making 10,000 or more crossings then screening their 40,000 or so seedlings for resistance still creates a result that would simply never occur in nature.

Niedermayr also voices discomfort with another emerging technique — CRISPR-Cas9 gene editing. CRISPR is often likened to photoshopping for DNA sequences, as it allows specific genes in a sequence to be activated or deactivated. CRISPR gene editing has already been used to develop Chardonnay clones that have resistance to powdery mildew. Could this technology ultimately sound the death knell for PIWIs? Vouillamoz thinks it could, although he points out: “There’s a risk that these clones will be patented, and the second problem is that only a few clones will be modified, so we would lose clonal diversity.”

Here’s the rub. Just as the creators of modern PIWIs have managed to get their progeny classified as Vitis vinifera, so the Osaka, Japan-based research team who discovered CRISPR-Cas9 initially managed to avoid the results of their gene-editing technique being classified as GMOs, theoretically bringing gene-edited classic grape varieties a step closer to usage in the wild.

GMO crops have been blocked by the majority of the EU since 2015, but in 2018 a new ruling extended this ban to include gene-edited crops as well. On top of that, the widespread consumer mistrust of GMO products is likely to extend to gene-edited varieties too — as evidenced by Thomas Niedermayr’s views. So for the moment PIWIs alone will continue to hold sway with growers who want to reduce their vineyard inputs to as close to zero as possible.

Whatever the future holds for development of resistant grape varieties, it is very likely that divisions between what is considered genetically modified or not, and what is or isn’t acceptable to organic, biodynamic and natural growers will continue to blur. 

Simon J. Woolf

Correction: This article has been updated to reflect the fact that PIWIs can be used for the English Quality Sparkling Wine category.

This article first appeared in Issue 3, 2020 of Meininger's Wine Business International magazine, available in print or online by subscription.


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