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8/28/00

Contacts:
Jeff Iles, Department of Horticulture, (515) 294-0029, iles@iastate.edu
Elaine Edwards, Extension Communication Systems, (515) 294-5168, eedwards@iastate.edu

Yard and Garden Column for the Week Beginning Sept. 1

No Bad Trees

By Jeff Iles
Extension horticulturist
Iowa State University Extension

In her most famous book "No Bad Dogs," the late Barbara Woodhouse describes how there really are no difficult dogs, only inexperienced owners. While dog owners (dog guardians if you prefer) might not totally agree with her thesis, I must confess after my wife and I enrolled our dogs in an obedience class in which we were the focus of the training, not the dog, life with our four-legged friends has become more predictable and enjoyable. So if there are no bad dogs, couldn't we make a similar statement regarding trees? Or are some trees simply bad news?

Actually, the more I evaluate tree performance in the landscape, the more I'm convinced that trees give us problems only when we force them to perform in situations for which they are poorly designed. I mean, you wouldn't take a Pomeranian pheasant hunting would you? So why do we continue to plant silver maples under power lines or Colorado spruce 5 feet from house foundations and then curse them when they outgrow the site? I think the time has come to stop laying blame at the roots of our trees and instead, accept responsibility for where we locate these valuable landscape components. Allow me to illustrate.

River birch is the classic example of a tree species saddled with a bad reputation through no fault of its own. With its peeling, cinnamon-brown bark and proven resistance to the bronze birch borer, river birch has become the birch of choice in many residential and commercial landscapes. But in our rush to embrace this useful tree, we either forgot or never bothered to investigate its site requirements. The fact is, river birch prefers to grow where the soil is a bit on the acidic side. But if you plant it in a new housing development where soils are typically poor and usually alkaline, I can almost guarantee your river birch will begin to display the sickly yellow foliage associated with a mineral element deficiency brought about by high soil pH. Pin oak, swamp white oak and red maple will behave in a similar manner, but are all of these bad trees? I hardly think so.

Another tree we love to lambaste is the Austrian pine. Seemingly thousands upon thousands were planted in the 1960s and 70s, and many of them are still with us today; however, most have the aesthetic appeal of an old Ford Pinto. You see, a couple of disfiguring conifer diseases caught up with them, and now instead of being the ace of the conifer lineup, Austrian pines have been forced into early retirement throughout much of the Midwest. Are they bad trees? Let's just say that Austrian pines would prefer to spend their time in a drier climate. In fact, travel 700 miles to the west and Austrian pine is still as popular as $1/gallon gasoline. Why? Less rainfall and lower humidity keeps disease infection levels very low.

And then we have the crabapples. Those nasty disease-prone trees are best known for dropping their messy fruit and leaves in mid-summer, right? Not that my crabapple friends need me to defend them, but let's not paint with too broad of a brush here. Keep in mind there are more than 700 different kinds of flowering crabapples from which to choose. And yes I'll concede that somewhere in that throng there probably are a few bad apples you'd rather not bring home to meet the folks. But, most, if not all of the selections found in Iowa nurseries and garden centers today have smaller, more persistent fruit and excellent resistance to disease. I just hate it when people make fun of the crabapples!

What about sycamore and catalpa? Certainly these behemoths with their large leaves and obnoxious fruit have to be considered bad trees. Don't get me started! When you decide to build your swimming pool or deck under the spread of their canopies do you really expect them to respectfully refrain from shedding their parts? Kind of like giving your new puppy the run of the house all day and expecting him not to...well...you know.

Had enough or do you need one more example? O.K. Silver maple is not a bad tree! There, I said it. Seriously, for golf courses, parks or other large properties, silver maples, planted far away from homes, places of business, garages and other important structures, can be very useful trees. Why? Because they grow fast and have relatively few serious insect and disease problems. Of course you wouldn't want an entire landscape filled with them, but there's no shame in planting a few silver maples to temporarily lend structure and visibility to a landscape until slower-growing, more desirable species mature.

Oh, and what about the 'Canada Red' cherry. You know, that little ornamental tree with purple leaves, black corky growths on the stems and lots of suckers shooting up around its base? Hey, wait a minute. That really is a bad tree!

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ml: isugarden


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