As we know, the Chestnut in the United States is a member of the Castanets genus, which is a small group of nut-producing timber trees. C. dentata, the American chestnut, was probably the most valuable timber tree in this country. Certainly it was the dominant tree in the vast hardwood forests. Unfortunately an Asiatic fungus, Endothia parasitica, which gained entrance to N.Y. about 1900, has all but exterminated the American chestnut in this country. Common in the hardwood forests of the eastern half of the United States, only an occasional sucker from the live root system isnow seen from Me. to Mich. and south to the Gulf of Mexico.
Sometimes the suckers become large enough to bear nuts arousing hope that eventually the American Chestnut may acquire resistance to the blight. The U.S. Forest Service, the state forestry departments and others, notably Dr. Richard A. Jaynes, have been crossing American chestnut with the Japanese species, Castaneacrenata and the Chinese species, both of which have resistance to Endothia. Some progress is being made, but hope of producing a timber-type hybrid with sufficient resistance to use in reforesting has not yet been realized.
Although a number of named varieties are available from nurseries, notably ‘Abundance’, ‘Carr’ and ‘Hobson’, because of incompatibility between seedling stock and the scion, many persons have had poor results with them. They are now turning to named selections of the Chinese chestnut which have been made by the USDA. Grafted trees come into bearing in 5 or 6 years. Seedlings often do not bear until 15or more years old. Chinese chestnuts have nuts as sweet as the American and often of larger size. Recommended are ‘Nanking’, ‘ Meiling’ and ‘Ruling’. All 3 produce large nuts of excellent quality. Although the Chinese chestnut is questionably hardy in Zone 3, it does extremely well over most of the country.
Very likely the resistance of both the Chinese chestnut and the Japanese Castanea crenata resulted from living with the disease for several hundred years. On that basis we may hope that eventually the American Chestnut will acquire a degree of resistance some day.
The Japanese Chestnut, C. crenata, is a spreading short-trunked tree that usually re-mains under 30 feet in height. Leaves are oblong, 4 to 7 in. in length with the margin serrated. The burr is about 2 in. in dia. and normally has 2 nuts, which lack the quality of the nuts of either the American or Chinese chestnut. It thrives in much of the country from Zone 4 south.
The Chinese chestnut, C. mollissima, may reach 50 ft. in height. The trunk, however, is short and the crown is broad. The elliptic leaves are coarsely toothed with a white pubescence along the veins. Native to China and Korea, the nuts, 2 normally to a burr, are large and sweet. Hardy from Zone 4 south, several producing orchards in the Midwest and the Middle Atlantic States yield plentiful crops of high quality nuts.
The Spanish chestnut, C. sativa, is a tall tree native to Europe, western Asia and North Africa. It has been in cultivation in Europe for many years. In this country, it is less hardy than either Asiatic species. The nuts are large and well filled when properly grown, but they lack the pleasant flavor of either American Chestnut or the Asiatic species. In recent years chestnut blight has reached Europe and is decimating the orchards of Spanish Chestnut.
The Chinquapin, C. panzila, is a shrubby American tree. Native from N.J. to Fla. and west to Tex. and Okla., its burrs are a little over an inch in dia. and normally contain a single nut. Leaves 3 to 7 in. long are coarsely toothed and have a white felt on the underside.
Interest in the chestnut for landscape use has in recent years been largely concentrated on the Chinese chestnut. It is an attractive spreading tree, both ornamental and equally serviceable as a shade tree. Neither the Asiatic nor the American chestnut is exacting in its soil requirement, but no Chestnut will thrive in soil where drainage is poor. A rocky well-drained hillside with a sandy loam is ideal for chestnuts.
The most serious insect pest is a tiny snout beetle which lays its eggs on the growing burrs in July. The grubs hatch and bore into the enlarging nuts within the burr where they feed on the kernel. These chestnut weevils can be controlled with any one of several pesticides, but it is advisable to inquire of the Extension Service of the State University as to timing and the specific chemical to use. Since this pest pupates in the soil under the tree, control may be had by pesticide treatment of the soil. Other insects are not usually troublesome.
The most serious disease of the Chestnut is the blight, Endothia parasitica, for which there is now no known control. It does not affect the roots which sucker freely. Such suckers sometimes live long enough to produce a few nuts. The U.S. Forest Service has acquired detailed information on several hundred American chestnut trees that have not been killed by Endothia. Records of persisting suckers are also in their hands. It is hoped that a disease-resistant American chestnut may be found to be reproduced vegetatively or to be crossed with a Chinese or Japanese Chestnut, thereby producing a resistant hybrid.