PIWI Grape Varieties

PIWI refers to grape varieties that have a high level of resistance to mildew diseases, notable Powdery Mildew and Downy Mildew. The acronym is from the German term “Pilzwiderstandsfähige Reben”. Why is this term so popular right now? There is a huge interest by wine trade and industry in growing and making wine more sustainably and part of this equation is planting more disease resistant vines. More disease resistance means less sprays, and in a conventional vineyard that means less costs and less pesticide residues in your wine. But how do hybrid grape varieties and organic grape growing fit into this concept?

Hybrids 

 PIWI is a general term that includes hybrids but packaged as a hipper, more marketable term. Hybrids, a breed between European varieties and North American varieties, got a bad rap after they were planted in France as a solution to phylloxera-devasted vineyards in the late 1800’s and in Canada’s early wine days. Today, they are on approved grape variety lists for many European wine regions, British Columbia and Ontario, although somewhat marginalized, and of course celebrated in Nova Scotia and other north-eastern regions. They are gaining back popularity and we have consistently earned international awards for our L'Acadie Blanc sparklings.

Organic grape growing and PIWI

As mentioned, selecting disease resistant grape varieties are part of the sustainability equation in the sense that there are less chemical sprays. But what about an organic vineyard? This is where the dial moves and less resistant varieties can still be grown sustainably. We use the following organic strategies in our less resistant vinifera blocks of Chardonnay, Sauvignon Blanc and Pinot Noir: pruning for air circulation, horsetail and compost teas, sulfur and copper. There is also a philosophy that the vines can live with mildew diseases as long as we can keep the clusters disease-free, a sort of probiotic strength approach that is achieved by timing of sulfur and copper application around the flowering stage.