WARNING: TAKE MY ADVICE WITH EXTREME CAUTION OR NOT AT ALL.
Michael Pound, Times Staff
But the trees native to this area continue to struggle against a fungal disease, dogwood anthracnose, that attacks the trees' leaves and branches, often killing the plant if it goes untreated.
The fungus that causes anthracnose, called Discula destructiva, isn't native to the United States, said Michael Masiuk, a commercial horticulture educator with the Penn State Cooperative Extension office in Allegheny County. The fungus that has attacked trees in this area probably entered the country sometime in the 1970s near Connecticut and spread from there.
Beyond that, its origins are a mystery - it has yet to be identified on any dogwood species occurring outside the United States.
It arrived in Pennsylvania about a decade ago, Masiuk said, and was initially very destructive.
"It was devastating in both the trees that you'd find in the woods or in the trees at the nurseries," Masiuk said. "It has slowed some since then, but mostly because we've done a better job at understanding how it can be treated."
The disease reproduces when the spots produce spores in the spring. The spores are then spread, either locally by runoff from rain or over a longer distance by birds or insects. When the spores reach other trees, they bore into the tree, especially its leaves and smaller twigs, causing death of the tissue in the immediate area.
Anthracnose can strike other trees in the area, as well. John Smith, an arborist with Smith and Thompson Tree Service in Beaver Falls, said it's common in maples and sycamores, especially after a wet, humid spring.
Soggy weather is a key in all cases, Masiuk said.
"If we have a lot of rainfall during the time when the leaves are expanding, the fungus is going to spread," he said. "That usually means it's going to be a lot more widespread that year."
What does that look like? Masiuk said brown spots on leaves - sometimes with a purplish margin around the brown - or twig dieback are signs of anthracnose problems.
"If you see a lot of those on your tree, you should take a look at ways to treat it," he said.
There are some simple things that can help. Pruning out any dead twigs, and removing fallen leaves immediately should keep the disease from spreading further the following season. If that fails, a fungicide - Masiuk recommended Daconil 2787, available at garden centers - should help as well.
"Some of the treatment depends on how valuable the tree is," he said. "If you're talking about a tree that is the centerpiece of your landscaping, you should probably be more aggressive in treatment with fungicides."
Another possibility is planting trees that are resistant to the disease. Masiuk said researchers at the University of Tennessee developed a kind of dogwood, called Appalachian Spring, that has resisted the fungus.
Virginia borders PA so these considerations may apply
