Emmy Varley

Truffle farmers never had to worry about demand. It is the supply side that is worrying, with global warming an ever more present threats to their success.

“You don’t market the truffle, you manage its scarcity,” said Jean-Charles Savignac, president of the French Truffle Growers Federation.

The 2010-2011 season’s output was a meagre 25 tonnes, a severe shortfall blamed on a lack of water, which is vital for the Tuber melanosporum, the scientific name for the black truffle cherished by gourmets.

“If we had supplied 100 times more, it would all be sold,” said Mr Savignac, recalling that annual harvests of 200 to 300 tonnes in the 1960s, sold without the slightest difficulty.

He said a century ago output reached a “somewhat mythical 1,000 tonnes,” and still found takers despite a smaller world population and far more difficult delivery means.

Explanations for the ever-shrinking supply began with the rural exodus that emptied the French countryside after World War II.

The truffle’s natural habitat was affected as farmland gave way to natural reforestation or bush, according to truffle expert Pierre Sourzat, who added that sometimes very effective competitors – other fungi that colonise tree roots – encroached on its territory.

Weather variations are no help. “The truffle, which is very sensitive to water, is something of a marker of climatic changes,” remarked Mr Savignac.

In the summer of 2003, when a devastating heatwave gripped France, “three-quarters of natural truffles vanished,” he said.

“In the plantations, two-thirds to three-quarters of the trees stopped producing the following years. Other mushrooms that are more adapted to drought beat out the truffle.

“Every year, we plant 300,000 to 400,000 trees in France, or around 1,000 more hectares dedicated to the truffle.

“With such a larger park to rely on, in the worst years we can reach an output of around 20 tonnes instead of the 10 tonnes we would get if nothing were done.” The sector also benefits from regional government subsidies, for example to fund experiments on improving production techniques. The region’s truffle growers hope this season will be better than last year’s, when only 500 kilos of the coveted Causses du Quercy truffles – which connoisseurs say has an “initial nose of strawberry jam”– were produced.