Today, European winegrowers face several severe challenges they have never experienced before. On the one hand, there is the ongoing climate change, which threatens viticulture in established regions with higher temperatures and highly variable weather conditions. But it also allows the production of wine in new regions previously thought too cold for grapevines. On the other hand there is a general trend for more sustainability in agriculture as the public demands sustainably produced products and politics passes new regulations for environmental-friendly and sustainable agriculture, e.g. by reducing the amount of pesticides used. Winegrowers will need to adapt to these challenges if they want to meet the demands and continue to produce high quality wines.

One of the options for adaptation are new, disease-resistant grapevine cultivars (also known as “PIWIs”) adapted to the changing climate. The European grapevine varieties, while being able to deliver high quality wines with good viticultural traits are unfortunately highly susceptible to the main pathogens of viticulture, most prominently downy mildew and powdery mildew. However, there are wild grapevine species, mostly in North American and Asia, which harbor natural resistances against these pathogens. Grapevine breeders aim to develop PIWI varieties by harnessing these resistances of wild species and combining them with the beneficial traits of our traditional European grapevine varieties, for example with the high quality of the wines.

The Julius Kuehn Institute – Institute for Grapevine Breeding (JKI) has been breeding PIWI varieties since almost one century and its breeding program will be described in detail as a general example for the development of new grapevine varieties by the many breeders and breeding institutions worldwide. The best breeding lines are selected over a timeframe of around 20-25 years in a four stage breeding scheme in which the different stages have different priorities for selection. E.g. resistance properties are the most important trait in the first stage, the seedling stage, whereas wine quality is the main selection criterion especially in the later stages.

As one of the first results of its PIWI breeding program, the JKI released the PIWI variety ‘Regent’ in the 1990s and it was very well adopted by German and European viticulturists and is still the PIWI variety with the highest acreage in Germany today. Two new varieties and their potential to face the challenges today's viticulture needs to deal with will be discussed in detail: ‘Calardis Blanc’ and ‘Calardis Soleil’.