There is a lot of talk about fungus resistant grapes (sometimes called PIWI, from German pilzwiderstandsfähige). But the descriptor is maybe poorly chosen. The “fungus resistant” grapes used today are hybrids, in other words crosses between Vitis vinifera (the European vine) and American vines, Vitis somethingelse (labrusca, rupestris…). They are developed to have the American vine’s resistance to fungal diseases combined with the flavour profile of a Vitis vinifera.
But none of these hybrids, which are now slowly starting to spread in the vineyards, have total resistance to all three of the most common fungal diseases in the vineyard, mildiou (downy mildew), oidium (powdery mildew) and black rot, which has been noticed this unusually rainy year when even “fungus resistant” grapes were attacked.
This has led some to question their usefulness.
But the fact that they have good tolerance rather than resistance to fungal diseases does not detract from their usefulness. Potentially, spraying can be reduced by 80% with these grapes.
Read more: vitisphere
