KNOXVILLE, Tenn. — Dogwoods in lawns and gardens don’t appear to be seriously threatened by a disease ravaging wild trees in mountainous or shady areas, a University of Tennessee plant pathologist said Friday.
Dr. Mark Windham said dogwood anthracnose is not as great a problem as feared for landscape dogwoods because they stay dryer and warmer than those in the woods.
Windham, a UT-Knoxville associate professor of entomology and plant pathology, also reported the finding of four dogwoods in Maryland that may be resistant to the disease. If tests confirm their resistance, he said, a years-long process of
cross-breeding to produce a resistant dogwood may not be necessary.
”In the landscape, we’ve found that unless Tennessee trees are above 1,400 feet or the landscape is deeply shaded, the disease doesn’t appear to be a problem,” Windham said.
He and other researchers have found the disease causes much greater damage to wild trees on northern mountainous slopes than those facing south.
”The foliage of trees on a southern slope often reaches temperatures above 95 degrees. The (disease-causing) fungus won’t grow at temperatures above 80 degrees,” Windham said.
In Knoxville, where the Dogwood Arts Festival opened its
17-day run Friday, he said the only yard or landscape dogwoods heavily damaged by the disease were those sprayed by an irrigation system or on high, cool ridges.
”If you can fertilize the tree when necessary and water it at the base, you can keep most trees healthy if you’re in an area where the disease is present,” he said.
Windham said new dogwoods should be bought from a certified nursery with inspected stock and planted facing the south where they can get maximum sunlight.
The worst outbreaks of the disease in Knoxville have been on the ridges in Fountain City and in three West Knoxville yards with irrigation systems, he said.