ARBORICULTURE Trees require pruning and TLC

One of the big killers of trees is planting them too deeply.
KNIGHT RIDDER NEWSPAPERS
PHILADELPHIA -- This is the season when diligent homeowners stand outside and gaze up into their trees. Not to admire the foliage -- to make sure their trees are in good shape to withstand winter storms.
Some whose trees were toppled by Isabel or other recent storms may be replanting this fall. It's important to choose the right tree for the right place -- and to plant them properly -- to avoid problems.
Regardless of what happened during recent storms, before winter comes, responsible homeowners will do what they always do around this time: a visual check of all their trees.
What are they looking for?
Leftover storm damage or anything else that looks like a potential problem: "hangers" caught in the canopy (branches that haven't fallen, but could); dead branches; branches that are damaged but not fully broken.
"The first step in pruning any tree is removing damaged, broken or dead branches," says Paul Meyer, director of Morris Arboretum of the University of Pennsylvania. "Then, shortening or removing branches that are brushing houses or rubbing on gutters, shutters or shingles, followed by a general light thinning out of the tree."
Most of that should be done by a professional arborist, he points out. Homeowners should never climb trees or attempt to cut anything that's more than a few feet off the ground.
"Most large trees ideally should be visited by an arborist every three or four years," Meyer says. "If a branch falls occasionally, it's not necessarily an indication of anything in particular. Branches most likely to break are branches that are in decline, so some of that can be spotted by an arborist."
It's a good idea to use a certified arborist, such as those who belong to the International Society of Arboriculture.
"It's a voluntary certification system, but certification assures a basic level of knowledge," Meyers says. "And don't feel shy about asking for a certificate of insurance. Arboriculture is dangerous work, and you want to make sure that your contractor is adequately insured. That's often the difference between a cheaper arborist and a more expensive arborist: The one without insurance can operate much more cheaply than the one with."
You also can avoid potentially costly problems by growing trees that have the right attributes for their sites.
Fashion mistake
Don't be swayed by what's in fashion. A couple of decades ago, everybody was crazy about the Bradford pear. This cultivar of the callery pear seemed like the perfect tree: It was drought-tolerant, transplanted easily, didn't mind urban conditions, and had beautiful white flowers in spring and lovely color in fall.
But people didn't realize until later that it also is very brittle, and that the narrow angle at which its upright branches join to the trunk make it intrinsically weak.
"It's pretty predictable that they will come down in a major storm," Meyer says of those branches. "When you have a trunk that divides into two at a narrow angle, the tendency is to split out and break away."
He mentions the Aristocrat as one alternative, a cultivar that reputedly has better branching and more resistance to breakage.
"But the broader issue is of diversity, and the importance of not getting hooked on one kind of tree," he says, adding that Bradford pears "have been grossly overplanted" in many communities.
"There are no perfect trees, so the way you deal with that is to hedge your bets," by planting a variety of trees.
So you wouldn't want a Pyrus calleryana "Bradford" close to your house. Nor an ash.
An arborist's stringent pruning may have bought it some time -- at least it didn't shed any more limbs during Isabel -- but maybe it's simply getting old and brittle. Trees have a natural life expectancy, and for an ash that could be 80 to 120 years, according to Meyer (although it might also last 50 additional years).
"So many of the trees that we enjoy were planted 80 to 100 years ago, and in many cases, they are over-mature. It's time to replant," he says. "For the most part, our grandparents planted a lot of the trees whose greenery we enjoy, and we haven't been keeping up with the losses."
Look to the future
And often when we do replant, we choose fast-growing, inexpensive, smaller flowering trees.
"But we also need to be growing the heritage trees of the future," the big ones that tend to be slower-growing as well as long-lived, and often are more expensive, Meyer adds.
"For example, black gum, black oak, white oak and even, in some appropriate areas, things like hickories that are an important part of our forest flora. They drop nuts, so you wouldn't want them as an urban street tree or a patio tree."
Or, if you want a big tree that grows a bit faster, consider the London plane tree, a favorite for urban conditions.
"There are two relatively new cultivars, Columbia and Liberty, that are highly disease-resistant to the [sycamore] anthracnose problem," he says, referring to the fungus that has bedeviled many sycamores, especially in this year's wet conditions.
"They rehybridized the American sycamore and the Oriental plane tree, and the chief aim was disease resistance."
Whichever tree you choose to plant this fall, take note: Things have changed a bit on the planting front. Experts no longer advise to add a lot of rich amendments to the soil in the planting hole, for example.
"If you have an organic, highly amended soil that changes abruptly to a heavy soil in the surrounding landscape, that works like a pot," Meyer says, and could cause the plant's roots to girdle rather than growing out into that heavy soil.
Instead, dig a hole much wider than the root ball -- but no deeper, because one of the big killers of newly planted trees is planting them too deeply. Even if you backfill the hole, the fill settles and the root ball ends up being too deep.
"The key thing that most people don't realize is that roots need oxygen, and if you plant them too deeply in heavy clay soil, they don't get the oxygen they need to grow," he says.
So plant the tree so that the root crown -- that little flare of the trunk -- is 2 or 3 inches above the surrounding grade. (If you see a tree trunk going into the ground like a telephone pole, it's probably planted too deeply.)
Protect it from drying out by creating a soil "saucer" around the tree to channel water to the roots, and then cover the whole area with 2 or 3 inches (but not more) of organic mulch. Feather the mulch out from the center so there is no buildup around the trunk.
Whatever you do, avoid creating those so-called "mulch volcanoes" that you see so often in suburban front yards, with mulch piled a foot high around tree trunks. All that does is smother the roots and provide a cozy home for rodents that want to gnaw on the bark.
Finally, consider buying a "water gator" for your newly planted treasure. These are water reservoirs that you can fill quickly with a hose and position around the tree's trunk, where they allow water to drip slowly onto the root ball.
As nurturing goes, you could think of it as the horticultural equivalent of a baby's bottle.