THE PIWI most common belong to the varieties Bronner, Cabernet Carbon, Cabernet Cortis, Gamaret, Helios, Muscaris, Johanniter, Prior, Regent and Solaris. Most of them are of German origin because historically Germany is the country most attentive to the selection of Pilzwiderstandfähig, that is i resistant vines with mushrooms, in acronym PIWI. Austria and Switzerland follow.
In Italy, Veneto, Trentino Alto Adige and Friuli Venezia Giulia lead the research on PIWI, with work that sees the Edmund Mach Foundation - Agricultural Institute San Michele all’Adige, Innovitis (private institute based in Bolzano), the University of Udine and the CRA-Vit of Conegliano Veneto (Treviso) at the forefront. The latter, in particular, began a selection process aimed at the production of resistant vines starting from Glera and Raboso Piave.
Furthermore, Veneto Agriculture, on behalf of the Region, has planted two vineyards with varieties and selections of PIWI created by the University of Udine and the Experimental Institute of Friborg. In compliance with the law that in Italy subjects i fungus resistant vines to precise limitations. In particular, that which prohibits the allocation of the grapes harvested from PIWI to the production of DOC and DOCG wines (article 8, paragraph 6, of Legislative Decree n.61 / 2010).
Why the PIWI?
Because the European vine, Vitis Vinifera, is very sensitive to the attacks of powdery mildew and the devastating ones of downy mildew and botrytis, the two most feared fungal diseases of the vine. It has always been, not now, and that's why the first selections of vines PIWI they began between 1880 and 1935. The results, however, have long been poor and have damaged the image of resistant varieties as wine grapes. Today, more than a century after the first attempts, the selections of pilzwiderstandfähig give us wines that are difficult to distinguish from those obtained from traditional grape varieties. But it is also the concern for climate change that raises the attention of winegrowers for PIWTHE.
How are PIWIs selected?
The process of selecting the fungus resistant vines follows a standard pattern. First the crossings are made, then the seedlings are obtained which are exposed to the fungus (according to the criterion of the best exposure) and finally the resistant specimens are selected which will be evaluated from the enological point of view. Sometimes this selection is supplemented with marker-assisted selection which, on younger vine specimens, can highlight genotypes with resistance genes.
In both cases the process of selecting the PIWI it is very long. Just think that that of the Regent, one of the first fungus resistant vines to have been put on the market, it took more than thirty years. The trial began in 1967, registration was only possible in 2001.