PIWI – Experts from the Edmund Mach Foundation speak out

PIWI grape varieties are not only highly resistant – primarily to vine diseases – but also represent the epitome of sustainability. In the vineyard, many phytosanitary treatments are dedicated to combating humidity and fungal pathogens. In this context, exploring innovative approaches becomes essential, as traditional practices alone are insufficient to address the complexities of the current viticultural crisis. Research thus emerges as a critical tool to overcome vineyard challenges and mitigate the risks of reduced harvests.

The Italian Edmund Mach Foundation of San Michele all’Adige (Trentino-Alto Adige) is a benchmark of excellence in this field. To gain deeper insights into PIWI grape varieties –Pilzwiderstandsfähig in German, meaning “fungus-resistant” – which require significantly fewer phytosanitary interventions, we interviewed two leading experts: Prof. Marco Stefanini, Head of the Grapevine Genetics and Breeding Department at the Research and Innovation Center, and Prof. Andrea Panichi, Head of the Post-Secondary Education Department at the Mach Foundation. The interview follows below.

Are PIWI grapes GMOs?

Marco Stefanini

Absolutely not. All the grape varieties we cultivate, such as Cabernet Sauvignon – one of the most widely planted worldwide – result from natural crosses. For instance, Cabernet Sauvignon originates from the natural cross between Cabernet Franc and Sauvignon Blanc, both Vitis vinifera species. Most grapes used in wine production come exclusively from this species.

PIWI grape varieties are developed through a hybridisation process in which one of the parent vines does not belong to Vitis vinifera but to another Vitis species, such as Amurensis or Muscadinia. This genetic contribution endows PIWI varieties with enhanced resistance to diseases like downy and powdery mildew, significantly reducing the need for phytosanitary treatments.

It is crucial to emphasise that PIWI grapes are not GMOs (genetically modified organisms). Unlike GMOs, where specific DNA sequences are artificially inserted into the genome, PIWI varieties are created through natural fertilisation without any direct DNA manipulation.

Photo credits: Piwi International

Are there regulatory differences in cultivating PIWI grapes compared to traditional varieties?

At the European level, PIWI grape varieties are permitted; however, in Italy, they still cannot be included in the list of authorised varieties for PDO (Protected Designation of Origin) specifications.

In which countries are PIWI grapes most cultivated?

Andrea Panichi

PIWI grapes are mainly grown in countries where research centers began early experimentation projects. Germany and Austria led the way, followed by Switzerland, France, and Italy. Recently, France authorised a small percentage of these varieties for inclusion in the Champagne production guidelines. Italy also plays a significant role in their cultivation. The hope is that these grapes will be increasingly adopted across global wine-growing regions, promoting more sustainable viticulture.

In which international markets are PIWI wines most sold?

Andrea Panichi

These varieties have found strong markets in their countries of origin. For instance, Solaris, developed by the Freiburg Research Institute, has established itself in Germany, Austria, and Switzerland. However, their potential is gradually being discovered in Italy as well. Some Italian wine shops specialise in PIWI wines, and the Italian market is steadily opening up to these grapes.

Which types of PIWI wines are most commonly sold?

Andrea Panichi

Placing white PIWI varieties such as Solaris, Bronner, or Souvignier Gris on the market is undoubtedly more straightforward. These varieties generally exhibit refreshing acidity, which appeals even to less experienced wine consumers. Their acidity and the fact that white wines are typically served at lower temperatures make them immediately accessible and enjoyable. Serving temperatures between 4°C and 10°C enhance the perception of freshness, further increasing their appeal. As a result, white PIWI varieties have found greater market success due to their distinctive characteristics.

What is the primary market segment for PIWI wines?

Andrea Panichi

Regarding pricing, PIWI wines generally fall into the mid-range category, with some noteworthy exceptions of higher quality. Typical prices range from €7 to €15, though certain wines may command higher prices, justified by their superior quality in the glass. However, there are no PIWI wines within the super-premium price range comparable to iconic labels like Giulio Ferrari for sparkling wines or Sassicaia among still wines. Consequently, PIWI wines do not yet compete in these high-end categories. Their market presence is primarily concentrated within their production areas, with many bottles sold directly at wineries, in specialist wine shops and local Consortiums.

What are the sensory differences between white PIWI wines and traditional whites?

Andrea Panichi

The differences between PIWI varieties and traditional Vitis vinifera are relatively minor, starting with white wines. The grapes used for producing these wines tend to ripen slightly earlier, which helps preserve good acidity levels, both tartaric and malic. Overall, PIWI white wines are pleasant on the palate and closely resemble those made from traditional varieties.

When it comes to red wines, however, there is still room for improvement. The tannic component is often quite pronounced and overpowers other structural elements of the wine. This highlights the need for careful consideration during vinification and ageing processes, particularly regarding the duration and maturation methods. The distinction from conventional red wines is more noticeable, with PIWI reds showing notable powerful structure and lack of elegance, which is crucial for red wines.

As for sparkling wines, both Charmat and traditional methods, while they exhibit high acidity, have yet to achieve the level of elegance found in conventional sparkling wines. However, they are characterised by remarkable freshness, which makes them highly enjoyable, often featuring lively bubbles.

In the vineyard, frequent treatments contribute to soil compaction and reduce oxygen levels, which are crucial for soil health and the activity of microorganisms essential for fertility. Additionally, phytosanitary treatments often leave residues in the soil, gradually compromising its fertility over time.

On the other hand, PIWI grape varieties require significantly fewer treatments – typically one or two per year, depending on disease pressure, the growing area, and the season. While their quality is comparable or slightly lower than traditional varieties, PIWI grapes’ environmental impact is substantially reduced. This is particularly evident in the decreased reliance on tractors and other agricultural equipment, leading to lower carbon emissions and less soil disturbance.

Regarding the vineyard: how do PIWI grapes contribute to environmental preservation?

Andrea Panichi

To illustrate my point, consider this simple example: If ten treatments are needed for conventional varieties, that requires driving the tractor through the vineyard ten times. This results in much higher diesel emissions, greater soil compaction, increased risks for the operator, and more frequent water distribution, among other impacts. In contrast, using varieties that only require one or two treatments per year reduces diesel emissions by 80%, along with all the associated effects mentioned above. Growing PIWI vines significantly lowers the environmental impact, also limiting the effects on the soil’s microflora. Therefore, with equal or slightly lower quality than traditional varieties, the ecological impact is significantly reduced, making it more sustainable.

Now, I’m not suggesting that everyone should switch to cultivating PIWI varieties. The traditional varieties that have made Italian wine famous worldwide will remain central. However, it’s time to consider using PIWI grapes in specific areas of Italy, particularly where treatments are more challenging, such as in colder regions or forested areas. These varieties could also be introduced in more prestigious zones, as has happened in Champagne, where PIWI varieties are allowed as part of the blend. An option could be evaluating their inclusion in appellations or typical geographical indications, but legislators will ultimately need to address this matter.

If present in the cellar, what are the differences in wine production with PIWI grapes compared to traditional ones?

Andrea Panichi

Certainly, winemaking protocols will need to be revised and adapted in the cellar, which will take time. For example, it took 70-80 years to reach the level of vinification we know today for Chardonnay. The same applies to sparkling wines, the traditional method, and other wine styles. Multiple harvests are required to understand how a variety behaves in a particular terroir, climate, and winery, taking into account factors such as mechanical equipment availability and the winemaker’s choices regarding fermentation auxiliaries, like yeasts or the use (or not) of sulfur dioxide. Only after this extensive evaluation process can we establish a vinification and ageing protocol, especially for red wines, where it will be crucial to make thorough considerations.

Indeed, there are differences between grape varieties and regions, and it will take years to optimise these grapes’ potential fully. It’s essential to bear in mind that wine is in constant evolution. The Chardonnays we drink in 2024 are undoubtedly different from those of the 1990s, even those produced a decade ago. Moreover, the techniques for PIWI wines are still evolving, as we are in the early stages of cellar experimentation.

Earlier, you mentioned “mechanical availability”. What exactly did you mean?

Andrea Panichi

When I talk about “mechanics,” I’m referring to the equipment we enologists use to produce wine. For example, to extract must from a white grape for vinification, I can use a press, but there are also other tools like plate presses, pneumatic presses, and so on. The cooling system is essential in the cellar, as temperature management allows me, for instance, to perform cold extractions or regulate the vat temperature during clarification. Additionally, modern equipment made various interventions – from grape management to fermentation curves, fermentation duration, and the extraction of compounds such as aromas – possible. In essence, the availability of mechanical tools supports the enologist’s work. In Roman times, everything was different – not better or worse, just different, as were the wines of that era. 

Andrea Panichi

We are the first institution in Italy to create an event exclusively dedicated to the PIWI wines. This year, we reached the 4th edition, aiming to involve journalists, sommeliers, educators, restaurateurs, buyers, enologists, technicians, and other industry experts to taste the PIWI wines. This edition featured a total of 148 labels. Considering that around 380 are produced in Italy, experts have the opportunity to taste nearly half of the available labels, contributing to the correct dissemination of this wine category. The aim is to spread accurate information, as wines produced with PIWI grapes are often mistakenly associated with those vinified in amphorae or without sulfur dioxide. Instead, we aim to provide a more complete and truthful perspective, relying on external experts to ensure a correct and precise representation.

Please mention some varieties developed by the Foundation that growers can purchase today.

Marco Stefanini

A grape grower can plant the authorised varieties in their region or province. For the province of Trento, we have registered the Termantis and Nermantis in the National Register of Grape Varieties—both hybrids with Teroldego, as well as the Valnosia, which is a descendant of Nosiola, and Charvir, a pioneering cross between resistant varieties. These varieties are characterised by excellent qualities, allowing them to complement the typical productions of their parent varieties. We use molecular markers for resistance, ensuring that the progeny plants have a longer lifespan, significantly reducing the risk of fungi evolving and surpassing resistance levels.

What is a resistance marker?

Marco Stefanini

A resistance marker is a specific sequence of nucleic acid bases (DNA) that statistically indicates a 95% probability of the presence of the associated trait. Therefore, detecting this marker with a probability higher than 95% means the plant in question is effectively resistant or possesses the resistance indicated by the marker.

How many hectares in Italy are cultivated with PIWI grapes?

Marco Stefanini

Official data on the surface area planted with PIWI grapes in Italy is difficult to obtain. However, according to the most recent estimates from 2024, approximately 100 hectares in Trentino are cultivated with resistant varieties. It is estimated that over 2,000 hectares of PIWI grapes are planted in Italy. The main obstacle for Italian winegrowers is that these grapes are not yet authorised to produce wines with a controlled designation of origin, limiting their spread. However, it’s worth considering that about 50% of the wine produced in Italy is table wine, which implies that a significant portion of production could become more sustainable through PIWI grapes. Additionally, these varieties are allowed in IGT (Typical Geographical Indications), further expanding their potential.

Today, viticulture in Italy could become one of the most sustainable agricultural activities, with the Mach Foundation playing a leading role in this field. This type of activity requires expertise, technical-scientific support, and, above all, significant financial investments. Institutions capable of offering all of this are rare. Since 1985, the Foundation has chosen to pursue this path, with the full support of the administrators who have always shown interest in this project. In Italy, there are essentially two breeding centers dedicated to this field: ours and the group from the University of Udine with VCR, the largest nursery in the world. More recently, CREA in Conegliano has also launched breeding projects.

What support does the Foundation offer growers?

Marco Stefanini

First, winegrowers are updated on the latest developments, particularly new genotypes, through field visits during the ripening phase, allowing them to observe the cluster’s shape and presentation directly. Subsequently, tasting events are organised throughout Italy to evaluate the organoleptic profile of the new wines and spread awareness. Making PIWI varieties known is crucial, as they contribute to more sustainable viticulture, reducing the environmental impact with up to a 70% decrease in treatments. Farmers are particularly interested in these varieties, especially after the last two challenging years of phytosanitary management. It’s essential to identify, among the 36 varieties registered in the Italian National Register, those best suited to local conditions and each grower’s specific needs based on the style of wine they wish to produce. In addition to research and development, the Foundation is also involved in experimental studies to identify the best plant management conditions to express varietal character and achieve high product quality.

Are there any activities planned for 2025 aimed at promoting PIWI varieties? Will there be initiatives targeted at producers?

In 2025, likely in February, the second assembly of PIWI International-Italia will be held, an association that brings together national and international producers. The event aims to promote knowledge exchange and highlight the potential of resistant grape varieties. To this end, a logo has been created and patented, exclusive to members, which provides consumers with an indication of the type of product. In the following months, there will be numerous tasting opportunities. In particular, in August, there will be an “open doors” event to showcase the “on-field” situation of the production of resistant varieties. Additionally, the 5th edition of the PIWI varieties exhibition will be organised. We are considering moving the event to January or February to avoid the months of November and December, which are generally busy for producers due to marketing and cellar operations.

Will there be exhibitors with PIWI wines at Vinitaly?

Marco Stefanini:

Indeed, several PIWI wine producers are already present at various stands at Vinitaly. However, at Vinitaly 2026, we can secure a dedicated stand to give a voice to all producers, including the smaller ones, who are committed to producing PIWI wines.

This concludes our interview, which highlighted PIWI grapes’s growth and the Mach Foundation’s significant work in this field. In the following article, we will share our experience as judges at the fourth national PIWI wine exhibition, held in November at the Foundation, and we will discuss our impressions of the approach to these varieties.

Interview by Elena Francia DipWSET and Roberta Costante DipWSET