The Journal Gazette
 
 
Tuesday, November 23, 2021 1:00 am

Chestnut blight keeps trees from growing locally

Ricky Kemery

Question: I would love to grow American chestnut trees on my property to harvest the nuts for the holidays. Is this possible?

Answer: The quick answer to this question is no – though work on developing resistant American chestnut continues, but not without some controversy.

The American chestnut was once common in the Oak-Chestnut dry woodlands of the eastern United States. Chestnut blight – a fungal disease (introduced from trees from China) at the Bronx Zoo in New York in 1904 – killed approximately 3.5 billion American chestnut trees in less than 50 years. Chestnuts are considered functionally extinct because the blight fungus does not kill the tree's root system underground. American chestnuts attempt to survive by sending up stump sprouts that grow vigorously in logged or otherwise disturbed sites but inevitably succumb to the blight and die back to the ground. It is very rare to find even a stump sprout chestnut in the forest.

Chestnuts were fast-growing, rot-resistant, and the wood was used to make cabin logs, barns, furniture, fence posts and railroad ties. Sweet, acorn-size nuts were prized by wildlife. Cherokee people made dough from the crushed nuts, treated heart troubles with the leaves, and dressed wounds with astringent brewed from the sprouts. In Appalachia, the heart of the tree's native range, generations of people were rocked in chestnut cradles and buried in chestnut caskets.

The edible nut contains twice the amount of starch as a potato. Farmers would sometimes let their cows and pigs into the forest to forage for the nuts. People also ate chestnuts, which they not only roasted but ground into flour to make bread, cakes and puddings. Chestnut ripening coincided with the holiday season and turn-of-the-century newspaper articles often showed train cars overflowing with chestnuts rolling into major cities to be sold fresh or roasted.

The American Chestnut Foundation has worked to implement a breeding program that would hybridize American chestnut with the naturally blight resistant Asian chestnut. These trees are then backcrossed to produce a blight resistance tree that preserves the genetic and growth characteristics of the American chestnut. Hundreds of thousands of hours of painstaking work across many years has gone into this breeding program. Some hybrids as a result of the ongoing and uncompleted breeding program are now available on the market, yet critics say that release of these hybrids for sale is premature.

Controversial efforts to produce genetically engineered chestnuts is also underway. American Chestnut Project scientists claim that genetic engineering will provide a faster solution. After experimenting with various genes and combinations of genes, they have settled on using a gene sequence derived from wheat that causes the tree to produce an enzyme, oxalate oxidase, which inhibits the spread of the fungus once established, making it less lethal to the tree

Enthusiasm for genetically engineered American chestnuts has so far been underwhelming. Some scientists and citizens are wary of introducing GMO trees into the wild.

One can purchase Chinese or European chestnuts online for the holiday meal. Be wary of sources that claim they sell truly resistant native American chestnut trees.

The Plant Medic, written by Ricky Kemery, appears every other week. Kemery retired as the extension educator for horticulture at the Allen County Purdue Extension Service. To send him a question, email trich@jg.net.


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