Evaluation of INRA chestnut interspecific hybrids

In France traditionally chestnut orchards are made of trees from Castanea. sativa species. Today, modern orchards are planted with inter-specific hybrid cultivars. This material shows some resistance to ink disease, and it is used as own-rooted nut varieties or as rootstocks for cultivars. Chestnut growers still consider these hybrids as not performant enough. Since 1986, an inter-specific hybridization program using French C. sativa clones, C. crenata and C. mollissima species, has been developed to create new cultivars resistant to Phytophthora and producing fruits of good quality. This program has yielded approximately 7000 hybrids between 1987 and 1996. These hybrids were placed in breeding orchards for evaluation between 1992 and 1999. During 6 years, each hybrid was observed and tested for fruit and agronomic criteria, resistance to ink disease and lately for resistance to chestnut canker. Today, 25 hybrids grafted onto 2 interspecific rootstocks have been planted in orchards in Dordogne and Bordeaux according to the "French fruit varieties Chart". Three hundred hybrids would be tested in 2004 for the last evaluation year. Three or four interesting hybrids would be planted in commercial orchard in next future. This work is a collaboration with the French chestnut growers and particularly the Douville CIREA station.