They give off strong aromas of garlic, fermented cheese and methane, and are so rare that they can fetch up to £9,000 a kilo. Now, the puzzle that has baffled experts for more than half a century on how to grow the elusive white truffle on a commercial scale appears to have been solved.
This week, scientists at France’s National Research Institute for Agriculture, Food and the Environment (INRAE) will reveal that, at a secret location in Nouvelle-Aquitaine, western France, they have cultivated 26 white truffles.
While more than 90% of the highly prized black Périgord truffles sold are cultivated, previous attempts to grow their rarer white cousins have failed. This good harvest follows two productive years in the experimental planting during which barely a handful were grown.
“This significant increase in production is very promising,” said mycologist and project leader, Dr. Claude Murat, from INRAE and the University of Lorraine, Nancy. “It confirms that the truffle is well established.
“With black truffle it’s common to have few truffles at first and then a rapid increase, and it looks like white truffle is behaving the same way, which is good news for the future crop.”
Truffles, like many other fungi, form symbiotic relationships with certain tree species by attaching themselves to their roots. They deliver additional water and minerals to trees in exchange for carbon-based nutrients.
Scientists developed a way to inoculate trees with Périgord truffles in the 1970s, leading to the establishment of thousands of plantations in France, Italy and later Spain. The same technique failed with the Italian white truffle (Tuber magnatum), despite planting more than 500,000 seedlings in Italy.
Some truffles were found in plantations 15 to 20 years after planting, but because they were in areas where T. magnatum occurs naturally, the researchers believe they came from native fungi.
Starting in 1999, researchers from the INRAE and the Pépinières Robin nursery in France produced genetically confirmed oak trees that had been associated with Italian white truffle. These were planted in a series of truffle orchards since 2008.
Tests of soil samples from five sites, all outside the part of the country where the species occurs naturally, showed that the fungus was present in four of these.
Three truffles were found in the Nouvelle-Aquitaine orchard in 2019 and four in 2020. The 26 found in 2021 weighed around 900g in total. So far, 12 of the 52 oak trees planted in 2015 have produced truffles.
“This is the first time that Tuber magnatum fruiting bodies have been grown in significant numbers outside their natural range, so it’s a very exciting development,” said Professor Paul Thomas, a mycologist from Scotland, the company Mycorrhizal Systems works with commercial partners to develop black truffle. plantations “Many previous attempts have failed, so we still need to know more about how they did it and how to replicate it.”
Murat and INRAE mycologist Dr Cyrille Bach have given details of the conditions under which the truffles grew, in research to be published in Le Trufficulteur, the magazine of the French Truffle Federation this week.
“We need to see the results of more experiments, but this opens up what could be an attractive possibility for truffle growers to diversify into a new market,” said Alain Ambialet, president of the French Truffle Federation.
Rising temperatures and reduced water availability in Spain, Italy and southern France are, some say, opening up opportunities for truffle entrepreneurs further north, including the UK. “With acres of calcareous soil and less water stress, there is good potential for growing truffles, including white truffles in the UK,” Murat said.