(DW) - Grape rot fungus costs the global wine industry millions each year. Amid health concerns over chemical solutions, a natural alternative is being tested in France's Bordeaux region - with positive initial results.

Saint Emilion, one of Bordeaux's most prestigious winemaking areas, is home to a vineyard called "The Grace of God." Owner Thierry Audier's great grandfather started making wine here a century and a half ago.

Come September, the new leaves on the vines and bunches of grapes the size of walnuts will be heavy bouquets of dark fruit. That is, if they survive the botrytis (also known as grape rot or bunch rot). The fungus usually ruins around a quarter of the crop, sometimes more.

To combat grape rot, Audier has been testing a natural pesticide called Mevalone, developed by Eden Research out of the United Kingdom.