the investigators in this field, Van Fleet,[1] of the United States Department of Agriculture, crossed Asiatic and European forms with the American chestnuts, the latter consisting of Castanea dentata, the forest tree, and C. pumila, a shrubby species growing in the southern states. The last species appears, by-the-way, to be somewhat resistant to the blight. Van Fleet says:
The results of these undertakings have been successful, in the main. The appearance in 1907 among our plantings of the terribly destructive new bark disease organism, Endothia parasitica, put a summary termination to the experiments with C. americana (dentata) and its derivatives, but selection work has since continued with self and chance-pollinated individuals of the chinquapin and Asiatic types.… The Asiatic chestnuts, and the chinquapin-Asiatic hybrids, are plainly highly resistant. Few have shown any appearance of infection and when noticeable the injury is quite local in character. Second generation seedlings of chinquapin-crenata crosses show no disease at all although always exposed to infection.
The nuts produced by these chinquapin-Asiatic hybrids are of decididly superior quality, so that, if they continue free from disease, they will solve the problem from the standpoint of the chestnut orchardist. It is doubtful, however, whether they will ever attain the size of forest trees. But it is quite possible that an immune variety for timber purposes may be produced by crossing a form like the Chinese chestnut, C. mollissima, with our native forest tree.
Work of this kind is extremely valuable and, although slow in yielding results, may eventually prove to be the only means of continuing the existence in our land of a greatly esteemed tree.
- ↑ Van Fleet, Walter, "Chestnut Breeding Experience," Jour. of Heredity, 5: 19–25, 1914.
