Chestnuts Roasting by an Open Fire...
—Michael Penziner, FRNC Docent
A family stands by a large dead chestnut tree, circa 1920. Photo: American Chestnut Foundation
The words of that song bring thoughts of those wonderful roasted chestnuts that are part of the tradition of winter. But we must tell you that the chestnuts you remember were not American chestnuts, they were either Italian or French. And that's because by the mid-20th century, over 4 billion of our native chestnut trees had been destroyed by an alien fungus, leaving a few patches of chestnut outside of the area of this northeastern forest. Our chestnut was the dominant tree in the northeast. One in every four hardwood trees was an American Chestnut (Castanea dentata); it grew straight and as tall as 100' high and had a trunk which could reach 14' in diameter. That is huge!!!
In the mid-1800s some Asian chestnut trees were imported into this area as landscape trees, and in 1904, at the Bronx Zoo, it was noticed that some native chestnuts were dying. A fungus, to which the Asian trees had developed a resistance over the millennia, had been brought in with those Asian trees, and spread to the American trees. The fungus infected any wound on a tree, and by changing the pH content of the sap effectively killed all the tissue above the wound. But that left the wood beneath the infection alive because it was successfully saved by chemicals which the tree produced closer to the roots. It's a complicated process, but that's the way it works. The effect is that some of the trees were not killed, but rather died down just to the area of the roots, so that they were able to grow and sustain new shoots for enough years to be just about ready for sexual reproduction, and at that point the new shoots died right back to the ground again without reproducing, until starting a new shoot once more. Now, the good news is...
We've got one of the live ones right here at the RNC!!!
And now for some more really good news. Researchers have been able to cross our native chestnut with a Chinese chestnut which is basically immune to the ravages of the fungus. So that gives us a tree which is 50-50 immune. Then they've crossed that 50-50 tree right back again to a Chinese chestnut to produce one that's 75% immune. Re-cross once again and the result of that cross gets crossed once more to the Chinese tree and you get a chestnut that's mostly American. Obviously, this has taken years and years and years, but the re-creation of the American chestnut and the impressive northeastern forest is well on its way.
