+Introduction+
Just about forty years ago the first blight resistant chestnuts were introduced into the Southeast. This event was to have more far-reaching effects than could be foreseen at that time, as is illustrated by the present extensive interest in the growing of these chestnuts as an orchard crop.
Chestnut blight, a fungus disease of the native American chestnut (Castanea dentata (Marsh) Borkh), first appeared on Long Island in 1904 and destroyed this magnificent nut and timber tree. A Phytophthora root disease added its toll so that a bearing tree of this species is a rarity in the East at the present time. The U. S. Department of Agriculture began making introductions of two species of chestnut from the Orient in 1906, both of which were resistant to the blight which was then destroying the native American chestnut. Of the two species, the Japanese chestnut (C. crenata Sieb. and Zuce.) and the Chinese chestnut (C. mollissima Bl.), only the latter proved to have much merit other than blight resistance and chestnut growing in the eastern United States in recent years has been confined almost entirely to the Chinese chestnut.
About twenty-five years ago, after the first introduction from the Orient of seed nuts of blight resistant chestnut species, the U. S. Department of Agriculture distributed a few seedling trees to various interested growers in the Southeast. Some of these trees are still growing and bearing good crops of nuts and have reached rather large size. The distribution of trees produced from nuts imported at subsequent intervals was continued by the U. S. Department of Agriculture until rather widely scattered planting of several species under varied soil, climatic, and cultural conditions was attained. As time passed it became clear that only the Chinese chestnut had promise as a commercial crop for the production of nuts. As a timber tree none of the introduced species has as yet shown outstanding merit.
[Footnote 2: Formerly Associate Pomologist, U. S. Pecan Field Station,
U. S. Department of Agriculture, Albany, Georgia.]
+General Observations+
The Chinese chestnut grows well throughout the southern part of the natural range of the American chestnut and southward to the Gulf Coast, and possibly even into central Florida. Farther north it apparently grows and produces better crops along the Atlantic Coast than inland, thus indicating the need of this species for a long growing season and freedom from late spring and early fall frosts. In the plantings in Georgia, from Atlanta to the southward, no loss of crop from late spring frosts has ever been noted. In the Gulf States and northward along the Atlantic seaboard the Chinese chestnut tree is vigorous, healthy, and productive, coming into bearing at a fairly early age and thereafter producing regular crops. The trees grow to be rather large in size, developing a somewhat rounded form with a spread of branches about equal to the height. Without pruning when young many sprouts usually develop near the ground so that the mature tree has numerous trunks of about equal size, with the lower lateral branches resting on the ground.
Nearly all of the Chinese chestnut trees being grown at the present time are seedlings and exhibit a wide range of tree and nut characteristics. A few trees develop a somewhat more upright type of growth than that commonly seen, but this type is generally less productive than trees of more spreading habit, and the nuts are smaller and less desirable. Some trees showing the most upright type of growth originated from nuts imported from the more northern provinces of China and may represent a distinct strain or form of Castanea mollissima. The degree of incompatibility exhibited when southern China strains are grafted on northern China strains would indicate the same conclusion. Unfortunately, several different species or strains have been included in the plantings of most cooperators with the U. S. Department of Agriculture so that seedlings resulting from cross-pollination of these types may exhibit an even wider range of characteristics and performance from the standpoint of commercial production than is commonly seen at present. A few of these hybrids may be superior to pure C. mollissima seedlings in certain important respects because of hybrid vigor, but taken as a whole the best types of C. mollissima seedlings are superior to the other blight resistant species for purposes of nut production.
The earliest introductions of blight resistant chestnuts from the Orient are represented by very few trees in the Southeast, but a small number of plantings of trees distributed in 1926 have been observed. These are producing good nuts and the trees are quite healthy, regardless of conditions of planting except when they have been given no attention of any kind. In one planting the trees were planted about 10 feet apart on the square with the result that they are tall and spindly with nut production only in the tops and very light on a per tree basis, which indicates the need of adequate spacing if the trees are to be vigorous and productive. Incidentally, this close spacing has not resulted in a desirable timber type of growth.
In two other plantings the trees are planted in cleared areas in cut-over timber and then given no further attention. In both locations a few trees are still living but are of no value either for timber or nut production. In still another planting on a bench about halfway up a mountain, where infrequent cultivation or mowing is practiced, the trees are growing and producing moderately well but the nuts are small. A few other scattered plantings of a few trees each are doing well around homes though receiving only moderately good care.