In the early 1950s, James Carpentar of Salem, Ohio, discovered a large living American chestnut in a grove of dead and dying trees. A member of the Northern Nut Growers Association, Carpentar was very impressed with the tree as it showed no evidence of blight infection. Over the next several years, he inoculated the tree with active blight spores and mycelia, but failed to induce any infection in the tree.

Carpentar sent budwood to Dr. Robert T. Dunstan, a fellow member of NNGA and well-known plant breeder in Greensboro, N.C. Dunstan grafted the scions onto chestnut root stock and the trees grew well. He cross-pollinated the American grafts with a mixture of 3 superior USDA released Chinese chestnut selections: "Kuling," "Meiling" and "Nanking".

In 1962, seedling trees from the first cross began to bear. Selecting the individuals with the most hybrid characteristics, Dr. Dunstan crossed them back to both the American and Chinese parent trees. The resulting second generation was moved to Alachua in north central Florida at "Chestnut Hill Tree Farm", where the trees have been growing and bearing every year for almost 50 years.

Dr. ROBERT T. (BOB) DUNSTAN

Born in Windsor, North Carolina in 1901, the "runt pig of the last litter" of Dr. Henry Vaughn Dunstan, a surgeon and survivor of the Civil War. His father passed away when Robert was only six years old and he was raised by his mother and two older half-brothers.

Bob Dunstan went to college at Trinity College (now Duke University), paid for with skins he hunted and trapped in the Albemarle swamps near Windsor. Majored in languages, receives his PhD, and become a professor of Romance Languages at the Women's College in Greensboro, NC. While he was in college, he was house-sitting for a professor who was away on sabbatical in France. The professor collected roses and sent home some grape vines along with rose plants. This was how Bob Dunstan became interested in the plants and soon began experimenting with growing grapes. He said that on the weekends he would play grapes instead of golf.

The French wine grapes sent by his professor died, killed by a virus called Pierce's disease, while the native American muscadines and scuppernongs thrived. Bob Dunstan set about trying to cross the two species to see if he could create a hybrid that would bear the beautiful bunch grape fruit that made the wonderful wines of France and California. Because the two species have different numbers of chromosomes, all of his efforts in breeding failed; the hybrids were sterile. However, by chance, Dunstan tried doubling the number of chromosomes using the mutagenic chemical Colchicine. The use of the tetraploid vines enabled the hybrids to become fertile and produce seed! He sent plants to geneticist, Dr. Haig Dermen, at the USDA Station at Beltsville. Dermen confirmed the hybridity and Dunstan published a ground-breaking article in the Journal of Heredity describing his work.

The hybrid grapes produced by Dunstan's crosses proved to have excellent resistance to Phylloxera, an aphid-like insect that was decimating the vineyards of France. By grafting the French wine grapes onto the hybrid rootstock, the vines became resistant to the infestation. This discovery saved so many vineyards in France that the Societe du Vin gave Dunstan a national award of honor, and he traveled to Paris and gave his acceptance speech in French.

This technique became very important in the effort to establish a wine grape industry in the eastern United States. Dunstan became widely known in plant circles for his work and retired to Alachua, FL in 1962 to continue his breeding efforts full time. He produced a number of new varieties and his genetic material was used in further crosses by many other breeders. Bob jokingly referred to himself as "a pimp to pollen"!

Dunstan was also a member of Northern Nut Growers Association (NNGA). It was Dunstan's affiliation with NNGA that provided him with the cuttings of the surviving American chestnut that he crossed with Chinese chestnuts to produce the Dunstan Hybrid Chestnut.

 

References:

  1. Dr. Robert T. Dunstan retrieved from: www.chestnuthilltreefarm.com