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Spring 2011

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

April 26, 2011

Devastated dogwoods

 |   An exotic disease is wiping out flowering dogwoods in the Appalachians.

Flowering dogwood, Cornus florida, infected with anthracnose.

As dogwood blooming peaks in late April, rusty-red splotches may appear on some flowering dogwood blossoms. These aren't the allegorical crucifixion-nail stains always seen at the tips of the flower bracts, but rather something truly diabolical: dogwood anthracnose, an exotic invasive fungus that is rapidly annihilating native dogwood trees.

Since it was first noticed in New York the late 1970s, Discula destructiva may have already wiped out more than half of the native

dogwoods in the Appalachians. Central Maryland has lost almost 75 percent of its dogwoods; 80 percent of Northern Virginia mountain dogwoods are gone. In some areas the tree has vanished.

Forest health may decline if deprived of the dogwood's contributions. The tree pulls calcium from the soil, concentrating it in its leaves. When leaves drop and decay, the mineral becomes available to other organisms and helps prevent acidification of soils. Many birds and mammals depend on

dogwood fruit as a food source in the autumn.

Dogwoods tend to be more resistant to anthracnose if they grow in higher-temperature, low-humidity areas with plenty of sunlight and adequate soil moisture. Regular controlled burning of forest floors helps maintain some of those conditions, and may be the most effective way to ensure the survival of this beloved native tree.

SOURCES: Cornell University, North Carolina State University, International Journal of Forestry Research, Forest Ecology and Management, forestencyclopedia.net