European grapevine (Vitis vinifera L.) is susceptible to powdery mildew (Erysiphe necator (Schwein.) Burrill), downy mildew (Plasmopara viticola Berl. Et de Toni) and grey mould (Botrytis cinerea Pers.). Several Vitaceae species from North America and Asia, throughout evolution, have developed resistance mechanisms against some fungi. First grapevine hybridsor offsprings of such vines were not as tolerant to these fungi as breeders wanted or expected. The most frequent problem was »foxy« aroma typically for American Vitis species. With several backcrossing with European grapevine (Vitis vinifera L.) they achieved that in the obtained hybrids the genome of European grapevine prevailed. In Slovenia some interspecific varieties 'Johanniter', 'Solaris', 'Muscaris', 'Souvignier gris', 'Fleurtai', 'Soreli' and 'Merlot Kanthus' were introduced, and in 2020 their inscription in the Vine selection is expected. After several years of introduction under Slovenian climate conditions the variety 'Johanniter' has shown the most tolerance to fungi of powdery mildew and downy mildew. Generally, the yield of most interspecific varieties varied among vintages causing the biggest problem. Despite the fact that vineyard planted with interspecific varieties are tolerant to certain fungi they have still to be treated with pesticides, but on a smaller scale, like vineyards in integrated pest management.
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