Resistant grape varieties

Effect of powdery mildew on the vine

Technical articles - Diseases, Climate resilience

Viticulture Viticulture Adapting the vine to climate change Downy mildew (vine) Powdery mildew of the vine Grape varieties Black rot Esca on vine

European grape varieties of the species Vitis vinifera are very sensitive to fungal diseases, making the use of phytosanitary products necessary for their production. Moreover, climate change confronts winegrowers with new challenges. Resistant grape varieties represent a major innovation to adapt viticulture to climatic and health challenges.

Resistance to fungal diseases

Grape varieties resistant to downy mildew and powdery mildew incorporate genes from American and Asian vines through hybridization with European grape varieties (Vitis vinifera). This approach helps reduce the use of phytosanitary products.

It takes 15 years to create a new resistant variety. The selection involves two steps:

• Hybridization: crossing two varieties carrying different traits that one wants to combine in the new variety. Since vines are hermaphroditic, the female parent is emasculated and then pollinated with pollen from the second variety.
• Marker-assisted selection is the second step, allowing selection among the seedlings only those carrying resistance genes. Field trials are then conducted over several years.

These resistant vines do not guarantee the cessation of fungicide use, as it is still necessary to maintain low disease pressure to prevent pathogens from overcoming vine resistance. Thus, two treatments per season are recommended.

Notable varieties include:

• Floréal, Vidoc, Voltis and Artaban are the first resistant grape varieties created in France under the Resdur program: their resistance is durable because it is conferred by at least two genes, making it harder for fungi to overcome.
  • Artaban: This black-berried variety is characterized by good resistance to downy mildew and total resistance to powdery mildew. It is known for its high productivity and mid-late ripening (meaning it ripens 12 to 23 days after the Chasselas, which is the reference variety), with strong color intensity and aromatic intensity.
  • Vidoc: Very resistant to downy mildew and powdery mildew, this black-berried variety has high productivity and late mid-season ripening. It produces full-bodied wines characterized by high color intensity and strong tannin content.
  • Floréal: This white-berried variety is also resistant to downy mildew and powdery mildew. It is known for its average productivity and mid-season ripening. It produces expressive and aromatic wines, dominated by exotic fruit and boxwood notes. It is partially resistant to black rot.
  • Voltis: This white-berried variety, also resistant to downy mildew and powdery mildew, has average productivity and mid-season ripening.

Souvignier Gris

• Beyond French resistant varieties, there are Souvignier gris and Muscaris, bred in Germany, and Soreli, originating from Italy.

• The Marselan, a hybrid of Cabernet Sauvignon and Grenache, is more resistant than many traditional varieties but remains more sensitive than those previously mentioned. It is slightly sensitive to powdery mildew but remains sensitive to downy mildew, especially on young leaves. It is an interesting variety because it combines partial disease resistance and drought resistance, inherited from Grenache.
• Coloris, a red variety obtained by INRA, has very high resistance to downy mildew, excellent resistance to powdery mildew, partial resistance to black rot, and very good resistance to botrytis.
• Pinot Meunier, a black wine grape variety resulting from a mutation of Pinot noir, is the only variety considered almost resistant to esca. It is also slightly sensitive to powdery mildew and downy mildew.

See also defense strategies against fungal diseases (beyond grape variety choice): Practicing biocontrol in viticulture

Frost resistance

The frost most commonly affecting viticulture in France is spring frost, which occurs at budburst. The vine is sensitive from the appearance of young water-rich leaves. In high humidity conditions, young shoots can freeze at -2 to -3°C, whereas in drier conditions (humidity <60%), they can withstand -4 to -5°C. These frosts never kill the vine but can destroy the harvest. Frost resistance strategies at the grape variety level include:

• Planting late-ripening varieties (Carignan, Mourvèdre): late varieties have delayed budburst, and the later the budburst, the less exposed it is to frost. Among these varieties is Mourvèdre. Originating from Spain, it is widely grown in southern France. Its late budburst and long phenological cycle make it less vulnerable to spring frosts. However, its late ripening requires favorable climatic conditions late in the season to reach optimal maturity. Traditionally, it was said in Provence that Mourvèdre must "see the sea" to ripen properly, highlighting its need for autumn warmth. However, even the latest varieties are not late enough for this strategy to fully protect production from frost.

• Agronomic research is working on clones and rootstocks to guard against March-April frosts with selection of late individuals that have not yet developed buds.

Mourvèdre

See also frost defense strategies (beyond grape variety choice): Protecting vines from frost

Drought adaptation

The vine is very sensitive to drought. Air bubbles appear in the sap-conducting vessels and prevent water transport when the xylem water potential drops below -2.5 MPa on average.

Marked differences exist between varieties facing water stress. Those resistant to diseases are the most sensitive to drought. With a P50 of -1.8 MPa, representing the water potential causing 50% loss of hydraulic conductivity, Floréal is the most sensitive variety, followed by Vidoc and Voltis. Thus, 50 days without water is enough to kill Floréal. Conversely, Pinot noir is the most drought-resistant variety, with a P50 of -3.5 MPa. It would take about 150 days without water to kill it.

Traditional varieties Pinot noir, Merlot and Syrah often outperform new disease-resistant varieties. Their vascular system better maintains hydraulic conductivity under stress.

See also drought defense strategies (beyond grape variety choice): Adapting the vine to climate change

Resistance to heat waves

A study conducted at Institut Agro Montpellier identified six genomic regions linked to tolerance to extreme temperatures, including genes involved in oxidative stress management and thermal signaling. These findings open the way for targeted genetic selection to improve grape variety resistance.

Grape varieties show varied responses to heat waves. Some, like Grenache and Mourvèdre, suffer from accelerated ripening and water stress, while others, like Carignan, although adapted to harsh conditions, show limits under extreme heat.

The best heat-adapted varieties are:

• Late-ripening varieties: a late variety requires more heat to reach maturity. It will therefore be better adapted to warmer climates and potentially less impacted by heat waves (depending on when the heat wave occurs).
• Vineyards also test varieties from other regions or countries with warmer climates. In Bordeaux, the Vitadapt program tests 52 varieties including some from Languedoc, Portugal (Touriga) or Greece (Assyrtiko, Lagiorgitiko).

See also heat wave defense strategies (beyond grape variety choice):

• Implementing shading systems in viticulture
• Adapting the vine to climate change

Uncertainties and limitations

Adapting grape varieties to climate change is a complex topic with divergent opinions depending on sources, contexts, and evaluation criteria. For example, while some studies consider Mourvèdre and Carignan vulnerable to heat waves due to accelerated ripening and water stress, other research includes them in adaptation programs (e.g., the Vitadapt program in Bordeaux), highlighting their late budburst and ability to preserve wine balance. These contradictions likely arise from the diversity of terroirs, viticultural practices, and production goals. The same applies to disease-resistant varieties like Vidoc and Floréal, where uncertainty remains about their behavior under very high temperatures.

Thus, rather than a single answer, the question of grape variety resistance to global warming requires a nuanced approach, taking into account local specificities and ongoing developments.

All these innovations come with challenges: long processes (15-20 years of R&D), appellation acceptance, and balancing multiple resistances. Research programs like CepInnov in Burgundy aim to reconcile these imperatives with regional typicities.