Fungus on Eastern Seaboard killing native flowering dogwoods

November 23, 1990|By Knight-Ridder

WASHINGTON -- The native flowering dogwood tree, prized for its springtime flowers and brilliant scarlet hues in fall, is threatened with destruction by an incurable disease sweeping the Eastern Seaboard, plant experts say.

In Maryland's Catoctin Mountain Park, where the presidential retreat Camp David is, the fungus already has killed 90 percent of the dogwood trees, known as Cornus florida.

In the dozen years since the fungus, called anthracnose, was detected in the New York Botanical Gardens in the Bronx, it has killed dogwoods in forests and woodlots from New York to Georgia and Alabama and as far west as Ohio.

An aggressive invader, the disease had a fourfold increase in its territory in 1989, according to surveys by the U.S. Forest Service. Disease spores borne by wind and water infected 2.1 million acres, most of it along the spine and ribs of the Appalachian Mountain chain.

"There's a lot of false hope that this is not going to be a Dutch elm disease or a chestnut blight," said Dr. Frank Santamour, a tree expert at the National Arboretum, referring to diseases that devastated other U.S. tree species in this century. This year the disease invaded the arboretum's 444-acre grounds in northeast Washington, which is planted with 70 varieties of the flowering dogwood.

Santamour exposed dogwood seedlings gathered from Maryland and 16 other states -- Alabama, Arkansas, Connecticut, Florida, Georgia, Kentucky, Louisiana, Mississippi, New Jersey, North Carolina, Ohio, Pennsylvania, Virginia, Michigan, Missouri and Oklahoma -- to the disease. All the trees died, he said.

"These results indicate that there is probably little hope for the selection and development of an anthracnose-resistant plant," Santamour concluded in the scientific journal Plant Disease.

Instead, he recommends replacing the dogwood with a remarkably similar tree, the Chinese dogwood, which is resistant to the blight.

But other plant pathologists hold out more hope for the native dogwood, saying that its popularity with weekend gardeners will prove to be the tree's salvation.

The trees most likely to survive are planted in a sunny spot in the suburban landscape, they say, where they receive regular watering, pruning, mulching and -- as a last resort -- spraying to keep them healthy.

Although there is no known cure for the disease, nurseries continue to stock the tree, which remains a favorite with gardeners and is a staple of the suburban landscape.

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