for more information contact Sandra L. Anagnostakis, The Connecticut Agricultural Experiment Station, Box 1106, New Haven, CT 06504, phone 203-974-8498, fax 203-974-8502
The appeal of chestnut, both for timber and for nut production, has prompted importation and experimentation in the U.S. for many years. In 1773, Thomas Jefferson grafted European chestnut scions (Castanea sativa Mill.) onto American chestnuts (C. dentata (Marsh.) Borkh.) at his home, Monticello, near Charlottesville, Virginia (1). E. I. Du Pont de Nemours moved from France to Bergen Point, New Jersey (in 1799) and then to Brandywine, Delaware (in 1802) where he planted European chestnuts himself, and gave them to friends and acquaintances (10).
G. Harold Powell's 1900 report from the Delaware Agricultural Experiment Station discusses the early history of Japanese chestnut trees (C. crenata Sieb. and Zucc.) in the United States. They were first imported by S. B. Parsons of Flushing, New York who obtained seed from plant collector Thomas Hogg in 1876. These `Parsons' Japan' were sold as original seedlings and their offspring, and two planted in Connecticut in 1876 still survive. William Parry of New Jersey imported 1000 grafted trees from Japan in 1882, and selected many of the early named varieties. Luther Burbank imported 10,000 nuts from Japan in 1886, and sold selected seedlings by mail-order, and to other nurseries.
Our first records of crosses between chestnut species typify the whole history of chestnut breeding in the U.S.: the work was done by both an interested amateur and by a professional botanist. George W. Endicott of Villa Ridge, Illinois was growing `Japan Giant' at the end of the last century, and used pollen from an American chestnut tree to produce Japanese X American hybrids in 1895. One of these hybrids produced six burs in its second year, and was named `Daniel Boone'. This variety was strongly self-fertile, which is rare in chestnut (11). The other early hybridization work was done by Dr. Walter Van Fleet, then an associate editor of the Rural New Yorker Magazine. In 1894 he used pollen of American chestnut on flowers of the European (or European-American) cultivar `Paragon' and planted the progeny in Little Silver, New Jersey (12). Van Fleet went on to make thousands of crosses, using many species, between 1900 and 1921. His early crosses used the native chinquapin, C. pumila and European and Japanese cultivars. In his later work he included the Chinese chestnut, C. mollissima Bl. Wild seed of "Castanea species" collected in Tientsin, China were imported by the US Department of Agriculture (as PI#34517) and planted in 1912 at their Bell (Maryland) Experimental Plot. Van Fleet had over 900 of these trees to observe and use there, in addition to subsequent importations made by the USDA plant explorer Frank N. Meyer. Van Fleet's S-8 (its row and tree location in the nursery) was crossed by Arthur Graves in Connecticut with a forest-type Japanese to produce the cultivar ‘Essate Jap’. Van Fleet did not have records on the parents of S-8, but H. Nienstaedt concluded in his 1948 thesis that it was C. crenata X C. pumila, based on the results of other crosses of these two species (9).
The USDA Yearbook of Agriculture for 1937 carries an article by H. L. Crane, C. A. Reed, and M. N. Wood, in which they discuss nut breeding in the U.S. Their work at Beltsville, Maryland and the work of R. B. Clapper and G. F. Gravatt at Glenn Dale, Maryland, and A. S. Colby at the Experiment station in Urbana, Illinois involved making and testing hybrids for their resistance to chestnut blight and their fitness throughout the US. The USDA work was continued by J. D. Diller and F. H. Berry until the project was terminated about 1960.
The contribution of many interested nut growers has been very important, both in spurring on the scientists and in educating the public. In Connecticut, physicians R. T. Morris and W. C. Deming planted many kinds of chestnuts and experimented with crosses and culture. Fred Ashworth in New York and Alfred Szego on Long Island, and many other faithful members of the Northern Nut Growers have contributed immeasurably.
The longest-continuing chestnut breeding program in the United States is that in Connecticut. Nut growers such as Morris and Deming encouraged The Experiment Station to study chestnut management before, and resistance after chestnut blight engulfed the state. Dr. Arthur H. Graves planted trees on land that he owned in Hamden, Connecticut, and started making crosses in 1930. Two of his students, Hans Nienstaedt and Richard A. Jaynes, maintained trees, made crosses, and contributed greatly to our knowledge of chestnut in general. In 1950 Graves deeded his land with the Sleeping Giant Chestnut Plantation to the state, to ensure that the work would continue. Since then the Plantation has been maintained by The Connecticut Agricultural Experiment Station, and is probably the finest collection of species and hybrids in the world.
The early Connecticut breeding work focused on making hybrids that were combinations of species, looking for single ideal progeny that could be propagated clonally. R. A. Jaynes joined the Experiment Station staff in 1962, and with A. H. Graves (who died in December of that year) published a bulletin on Connecticut hybrid chestnuts and their culture. Jaynes cooperated with the Virginia Division of Forestry to plant over 10,000 hybrid chestnut seedlings in the Lesesne State Forest in Virginia. These are still being observed by T. Dieroff, so that promising trees can be selected.
With Jaynes retirement in 1983, responsibility for the chestnut breeding program fell to me. At the urging of Charles R. Burnham, a prominent geneticist, records were searched for hybrids that were products of resistant X susceptible trees, and any that were backcrossed again to the susceptible parent species. Burnham felt that a few generations of backcrossing and selecting, followed by crosses of those products (Fig. 1), would allow selection of trees that had the form and nut quality needed, combined with resistance to chestnut blight (2). These trees would produce "true to type" offspring, and allow reforestation with chestnut.
Because of the long-term commitment of The Connecticut Agricultural Experiment Station in maintaining records and valuable trees, this project is proceeding smoothly. Many Asian trees in Connecticut have been evaluated for survival in our climate (some for 120 years, so far), resistance to chestnut blight, timber form, and nut quality. Selected trees have been used to make new hybrids with American chestnut trees kept alive using biological control by hypovirulence (a virus disease of the chestnut blight fungus). Experiment Station trees are also being used by Dr. F. V. Hebard, chestnut breeder for the American Chestnut Foundation. Two first-generation-backcross trees [(Chinese X American) X American] are now 50 and 43 years old. The hybrid made by Diller in 1946 was called `Clapper'(6), and although the original tree has died, two grafts survive at the Connecticut Experiment Station farm. Our other old BC1 tree was made by Graves and Nienstaedt in 1953, and we call it `Graves'. Both have timber form, good blight resistance, and acceptable nuts.
Selections are being made now for orchard as well as timber trees. Some of the complex hybrids made by Jaynes have the Chinese shrub C. seguinii in their background, and are compact dwarfs. I have used these as dwarfing rootstocks (to get early flowers on short trees), and am using them in crosses with chestnut trees with exceptional nut quality to select short, reliable nut producers.
The work at The Connecticut Experiment Station will continue, and the renewed interest in chestnuts should allow cooperation with many people -- amateurs and scientists -- to speed our progress towards usable chestnut timber stands and a new nut market in the United States.
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