Viticulture: Fungus-resistant grape (FRG) varieties need plant protection too
The wet summer of 2021 caused extensive damage to Switzerland’s vineyards. Fungal diseases such as downy mildew, in particular, took their toll on the grapevines. A survey conducted by the cantonal offices for viticulture in German-speaking Switzerland shows that FRG varieties are also affected by downy mildew and require plant protection products to protect the crop.
Friday, June 24, 2022
As reported by the Swiss Journal of Pomology and Viticulture (Obst- und Weinbau), FRG varieties were also affected by fungal infestations last summer. This was shown in a survey taken by around 130 wine producers. According to the results, about 73 percent of the FRG plots surveyed were affected by downy mildew. Of the standard varieties, 96 percent of the plots were affected by the fungal disease. In addition, FRG varieties were affected by the disease at a later stage, according to the survey, whereas symptoms of downy mildew were detected in standard cultivars even before the flowering stage. The disease did not appear in FRG varieties until the period between flowering and berry ripening.
More treatments in difficult years
Significant differences can also be seen in the diseased grapes. While only 9 percent of the standard-variety plots were free of diseased grapes, this figure was 50 percent among the FRG varieties. Although FRG varieties prove more resistant to downy mildew than standard varieties, they still need to be treated with plant protection products. In normal years, they require two to three treatments with copper and sulfur, according to Obst- und Weinbau. Last year, up to five treatments were required, depending on the variety.
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