Chestnut

Two breeding programmes shaped most of the named chestnuts a grower can buy today, and they were aimed at two different diseases.

In the United States the target was chestnut blight. Crossing began in the 1930s, pairing susceptible American and European trees with resistant Chinese and Japanese ones — work carried on at the Connecticut Agricultural Experiment Station, where Arthur Graves started making crosses in 1930 on his own land in Hamden and deeded that plantation to the state in 1950.

In France the target was ink disease, caused by a Phytophthora oomycete. The Laffite nursery in the Basque Country began breeding hybrid chestnuts in the early twentieth century, and INRA followed from the 1960s; from 1971 the work at INRA Bordeaux produced hybrids closer to the European species, and those now underlie French chestnut production. Several arrived as natural C. sativa × C. crenata hybrids found in the orchard at Migoule rather than as controlled crosses.

The practical consequence for a planting is that most European hybrids on offer are sativa × crenata, most American orchard cultivars are mollissima or complex hybrids carrying dentata, and the two groups were selected against different pathogens.