May 5, 1999 | By: Aimee D. Heald

Nearly everyone can appreciate the beauty of a flowering dogwood tree. The native Kentucky tree often is the victim of some nasty pests. Now it faces the adversity of powdery mildew.

"Powdery mildew symptoms may appear in mid-summer, long before the white powdery spores of the fungus, that causes the disease, are visible." Extension Plant Pathologist for the University of Kentucky College of Agriculture, John Hartman said. "Affected parts of leaves develop a mottled yellowing, or turn light green or yellow and develop brownish patches."

Hartman also said in some cases, the fungus is barely visible, yet in others it is more prominent. The disease can begin as light, reddish-brown or irregular purple blotches on the dogwood's leaves, which eventually turns to dark brown to tan patches.

Powdery mildew progressively increases from early June to early September. The most severely affected trees could be wilted and brown by late summer and the youngest leaves may be distorted and curled.

"Although it would appear to weaken trees," Hartman said. "Powdery mildew does not appear to be lethal. We have observed that under high disease pressure, flower production is decreased the following year."So, what can Kentuckians do to help out the dogwood's plight? Hartman said to avoid cultural practices that stimulate succulent growth, such as applying nitrogen fertilizer, heavily pruning and excessively irrigating. Also, apply mulch over the root system, prune out dead branches, and provide good air movement and light penetration by judicious pruning of nearby vegetation.

Do your part by planting dogwood species that resist powdery mildew, such as oriental dogwoods and cultivars. Make sure future generations can enjoy the beauty of dogwood trees in Kentucky.


Writer: Aimee D. Heald (606) 257-9764

Source: John Hartman (606) 257-5779