Truffle cultivation in Sweden: Results from Quercus robur and Corylus avellana field trials on the island of Gotland

The edible, ectomycorrhizal Burgundy truffle, Tuber aestivum Vitt., grows naturally on the islands of Gotland and Oland, Sweden. In 1999, 240 inoculated Quercus robur and Corylus avellana seedlings inoculated with French T. aestivum were planted in 10 experimental truffle orchards (truffieres) on Gotland to investigate the possibility of truffle cultivation in Sweden. Truffle orchard management, mycorrhizal development and seedling growth were studied. Fourteen additional truffle orchards containing more than 2000 Q. robur were established during 2000 and 2001. In 2004, T. aestivum mycorrhizae were detected in all truffle orchards. In 2005, the first T. aestivum truffle was found, 6 years after planting. This is the first cultivated truffle in Scandinavia and despite the northerly location they were produced within a timescale comparable with France. Tuber aestivum mycorrhizae survived in soils which differed from naturally producing locations by having a sand content > 95%, pH ≤6.4 and calcium content ≤0.1%. In a second series of experiments Swedish Q. robur, C. avellana and Carpinus betulus seedlings were inoculated with Swedish T. aestivum. Eleven months after inoculation T. aestivum mycorrhizae were found in 0-78% of the seedlings, depending on species, inoculation treatment and substrate. Because of the continuing decline of oaks in Sweden and associated fauna and flora, truffle cultivation may favour oak forest restoration programmes as well as making a direct contribution to rural economies.