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My wife and I were driving through the neighborhood about a week ago, and she noticed a number of trees that have become, it seems, her favorite among all others.  It's not surprising, they are one of my favorites as well.  "What are those trees?", she asked me.  They're Dogwoods, I replied.  Happy that I could finally identify one of her "What's that tree called" questions, I thought I had put the matter to rest.  Unfortunately, she followed up with the question "Why are they called Dogwoods."  Much as it pained me to do so, I had to utter the three most excruciating words in the English language for many men:  "I don't know."

My curiosity piqued, I started googling Dogwoods later that day.  I learned several bits of interesting trivia about them, as well as the derivation of their name.  But what I mostly read about was something that saddened me greatly.

America is losing her Dogwood trees.  If you live in the Northeast, along the Appalachian Mountain range or in the Piedmont region of the South, chances are you are aware of this already.  You may see it happening around you.  For others, who know the tree only as an ornamental landscaping tree that delights with its mid Spring white or pink flowers...you may only be aware that your tree has been doing poorly lately, or your neighbor's Dogwood died.

What's happening?  And why are they called Dogwoods, anyway?  For that, and more, stick around and have a read.

The American Dogwood Tree is of the genus Cornus, which derives from the Latin word for bull's horn.  The term attests to the wood's hardness.  The most common variety of Dogwood used ornamentally in landscapes is Cornus Florida.  The flowering Dogwood.

The common name dates from 15th century England.  Most probably from the Celts, who used the wood of the tree to shape into dagges.  That was the Celtic word for dagger, or shiv.  The wood of the tree was called Dagge wood, and tree came to be knbown as a Dagge tree.  Over time, and with Anglicization, it evolved into Dog Tree, or Dogwood.  When English colonists first arrived in North America, they immediately recognized the Dogwood trees that are so prevalent in our forests' understory.  West of the Rockies, from Northern California north through Oregon, Washington and British Columbia, another species of Dogwood is found, Cornus Nuttallii.

I have always admired this tree.  In the springtime, one can drive through Ohio's Hocking Valley, or better yet hike in its woods, and see the trees flowers sprinkled throughout the woods.  In the fall, the Dogwoods are immediately recognizable by their dull red foliage that contrasts with the mostly yellow leaves of the other trees.  But, as an understory tree, the Dogwood is relatively small.  I never considered it to be a source of hardwood of any import.

It is no longer used much for its wood, but there was a time when it had some very common, if specific, uses.  Due to the woods hardness, density and resistance to cracking, it was sought after to make the wheel bearings in many of the wagons used by pioneers here in America.  Similarly, it was the wood of choice in making early spinning looms on the frontier, and even up into the Industrial Age by commercial spinning factories.  Remember when golf woods were actually made from wood?  The better clubs used dogwood for the heads, since the wood so rarely cracked or split, and had a nice grain.  The wooden tennis rackets of 50 years ago also often used dogwood in their construction.

Though its use commercially has all but vanished, the trees simple beauty remains to grace the forests of much of the Eastern United States, and in suburban landscapes throughout much of the country.  But sadly, that may not be the case for too much longer.

In 1978 a disease was noticed by foresters that was attacking Dogwoods in the forests of New York.   It was also observed among the Dogwoods in the Pacific Northwest almost simultaneously.  In just 4 short years, it had spread at an alarming rate in the Northeast, and had already killed many of the Dogwoods there.  At first, scientists were stumped, on pun intended, as to the causative agent of the disease.  It was finally identified as Discula destructiva, a previously unknown, and seemingly brand new fungus.  It has since been commonly referred to as Dogwood Anthracnose.

Within the short span of just 15 years after its initial observation in isolated forest tracts, the disease had spread south from New York to Georgia, and had moved along the Appalachian mountain range from Pennsylvania to West Virginia, Kentucky and eastern Tennessee.  In some areas within that geographic range, the die off has been alarming.  In others, it has been only moderate in terms of tree death, but is still widespread as a disease that weakens, if not totally kills, the Dogwood trees.  Here's a link to a map that shows just how extensive the infestation currently is:
http://www.invasive.org/...

One researcher has reported that, after revisiting an area where he first observed the disease in the Chattahoochie National Forest, there were almost none to be found several years later.  In Connecticut's Catoctin Mountain National Park, a survey done in 1984 showed that 97% of the trees were infected by the disease, and a third of them were already dead.  Resurveyed 4 years later, the Dogwoods had suffered an 89% death rate.  In ecological terms, that is a pretty rapid decline.  And it continues.  What it means for the forest ecosystem is still an unanswered, but important question.  We are talking about losing much more than just natural beauty.

Today the disease is to be found throughout the Eastern forests.  It seems to be most severe at elevations above 3,000 feet, where microclimatic conditions favor the fungus' spread.  Between 2,000 and 3,000 ft, the impact is widespread but more moderate, and below 1,000 ft the Dogwoods have managed to survive with the disease to a much greater extent, though still show its effects.

I won't bog you down with details about the pathology of Dogwood Anthracnose, you can google it if you want those details.  But in a nutshell (is that another pun?), it causes lesions on the leaves and attacks tender shoots or suckers emerging from the trunk.  Any damage to the bark, say from deer foraging or rubbing their antlers, or broken branches, provides an open pathway for the fungus to invade the living cambium of the tree, which invariably results in the tree's death.  There is no effective, practical treatment for the native Dogwoods in our forests, though methods have been developed which can save individual trees that are determined to by of "high value", and those methods have practical implications for the Dogwoods used ornamentally in our suburban landscapes.

But many questions remain unanswered.  Where did the fungus come from?  Was it introduced into our forests from elsewhere, or did it mutate from another fungus, perhaps as a result of changing climate?  How would it's disappearance alter the forest ecosystem?  How would it impact wildlife?  Many birds forage on the tree's berries in the fall, which have one of the highest fat content among other food sources.  Migrating birds that feed upon them need this energy source to continue their journey.  Over-wintering birds like grouse and turkeys depend upon it to survive the cold.  So do rabbits, squirrels and deer.  The leaf litter they drop is high in Calcium, and there are questions as to how the micronutrient profile of the forest soil might change.  Would that affect other trees and vegetation?

Then there are the Dogwood festivals that are held throughout the country each Spring.  Would Charlottesville, Atlanta, Fayetteville and several other cities still continue, if the tree they celebrates were to disappear?  What would Paducah, KY's "Dogwood Trail" be like without Dogwoods?  Can anyone really imagine driving along the Blue Ridge Parkway in Spring without seeing the pink and white blossoms dotting the mountains?  Over half of the Dogwoods in Western North Carolina have already died, and in the more densely shaded parts of the forest almost 90% are dead already.  

If you have a Dogwood in your yard, here's what you can do to protect it as best you can, for this disease is everywhere, not just in the native forests.  Dogwoods have shallow root systems, and are easily stressed in times of drought.  So if it is dry, water your tree.  Don't use a sprinkler that wets the leaves, for that will only facilitate the fungus' growth.  Use a bubbler or soaker hose.  Try not to damage the bark by rubbing up against it with the lawn mower or scoring it with your string trimmer.  Remove any suckers that emerge from the trunk or lower branches.  It is helpful to remove grass from under the drip line, and put down mulch that conserves water and inhibits weed competition.  An annual application of all purpose fertilizer helps improve the tree's vigor, and a vigorous tree is better able to fend off a mild anthracnose infestation.  Prune damaged twigs or limbs, and apply a pruning treatment to the fresh cuts to seal them.  If you are considering a dogwood, but haven't yet planted it, site selection should be considered.  Deep shade will promote the fungus, but as understory trees Dogwoods prefer filtered light or at least afternoon shade.  As with any garden or landscaping issue, your local agricultural extension service will have detailed information more specific to your location, and it's only a quick google search away.

In the meantime, enjoy these trees in their natural state while they last.  When driving through the countryside in the Spring or fall, look for them and appreciate their beauty.  It may be fleeting, and who knows what the next 15 years will bring?  Our forests, like The Times, they are a'changing.

Originally posted to Keith930 on Sun Jun 24, 2012 at 09:59 AM PDT.

Also republished by Appalachian Journal and Community Spotlight.

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