American chestnut spreads new roots

Crossbreeding is a key strategy in the battle against an imported fungus that affects American chestnut trees

By Environmental News Network staff

Will the blight end the chestnut?
The farmers rather guess not,
It keeps smoldering at the roots/And sending up new shoots
Till another parasite/Shall come to end the blight
- Robert Frost

'Tis the season for roasting chestnuts on an open fire.

American tradition once dictated that, with the arrival of winter, chestnut lovers would harvest the morsels by the bushel and devour them like pistachios.

That tradition has faded just as the American chestnut tree has declined over the past century. But scientists are gaining new ground in a long effort to bring the tree back to abundance.

For 30 years, Sandra Anagnostakis has attempted to combat a deadly chestnut tree pathogen that was introduced to the United States from Asia at the turn of the century.

In a nutshell, all those years have allowed Anagnostakis to develop a keen instinct for saving American chestnut trees.

Dubbed "the redwoods of the east," American chestnuts once grew to heights of 100 feet. But when the foreign tree fungus hit in 1904, the complexion of eastern U.S. forests changed. After flourishing for some 40 million years throughout their range, from southern Maine to northern Georgia to the Ohio Valley, the trees were virtually wiped out in less than 50 years.

Today, the majority of chestnut trees are shoots that have sprouted from old chestnut-tree stumps. The new trees grow to a maximum of about 40 feet.

A blight canker is visible on this stem

"American chestnuts turned out to be really susceptible to the fungus," Anagnostakis said. "By the time (plant) pathologists got around to making inquiries about the disease, it had made its way up and down the East Coast."

To restore the "emperors of eastern forests" to their original grandeur, Anagnostakis and colleagues at the Connecticut Agricultural Experiment Station have crossbred American chestnuts with blight-resistant Asian chestnut trees. Using a biological control imported from Europe in 1972, they discovered two genes responsible for the resistance.

Since then, Anagnostakis has devoted her career to creating a disease-proof hybrid. Her patience hasn't worn thin.

"We can expect fully resistant hybrids in the next 10 years," she said.

"At the very least, we will be able to maintain American trees as nut-bearing populations. Then, if we plant our new resistant hybrids out into these plots, they will cross with native trees. The first generation offspring will be intermediate in resistance, but in subsequent generations trees with full resistance will be produced."

Copyright 2000, Environmental News Network, All Rights Reserved

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Connecticut Agricultural Experiment Station

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