Brushing his hand over crackling vine leaves, French winemaker Gregory Guibergia was relieved a wildfire only scorched the edge of his vineyard but he feared its smoke would ruin this year's vintage. In the last row of his fields in southeastern France, the wind rustled through the brown leaves of vines that overheated during a blaze that swept the region this summer. But plants further away were largely intact, with enough green leaves for their grapes to continue to mature in time for harvest next week. Guibergia said he was lucky after several wildfires in the surrounding Var region in recent weeks, which sent thousands of people fleeing – including Hollywood star George Clooney and his family – and destroyed more than 6,000 hectares (15,000 acres) of land. Read moreBad news for Bordeaux: France's celebrated wine industry faces wake-up call over wildfires But "the big question is whether or not we will have a burnt taste during the wine making", Guibergia told AFP. "We won't know straight away." He is one of many winemakers to be worried in France's main rosé-producing region, where flames have destroyed hundreds of some 30,000 hectares of vineyards, according to expert estimates. Guibergia, who has been in the business for 25 years, said he planned to pick the grapes and turn them into wine in several separate batches to help limit damage from any contaminated fruit. But he still dreads the possibility the product of his 25-hectare vineyard in the village of Correns could be declared undrinkable, and that he'd be unable to sell some 90,000 bottles. Lab tests In the surrounding region, experts have been testing grapes to see if they are still fit for wine. "An hour or two of exposure is enough to trigger glycosylation, or the binding of smoke to the sugars in the grapes," said oenology consultant Clement Prelat, who is advising winemakers in the area. "This smoky taste will only reveal itself after fermentation."