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Plant trees with their future size in mind; a common mistake is to plant spruce or pine trees too close to walkways and driveways, which they will quickly overgrow

July's Hot Topic:
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Let's Tell The Honest Truth!

Jim says: "If you're into masochism, you'll find pruning a barberry to be hours of nonstop fun. Don't wear white when pruning, though, as the bloodstains are terribly hard to remove..."

Stefan says: "It's a fast growing tree with fluffy white flowers in summer. As an added bonus, the flowers are perfumed with a repulsive odor which affords this plant with the alias of 'stink tree'..."

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Fellow Northscapers, there's a new storm brewing on the horizon. Chances are your yard or the landscapes nearby you are about to be affected by a very serious disease that is taking one of the most popular and important landscape trees from us in great numbers.

It's called bronze leaf disease, and it affects specific members of the poplar and aspen family (genus Populus). Unfortunately, it appears to affect the columnar Swedish aspen and Tower poplars the most. Here in the North we have precious few narrowly upright columnar trees (think of the famed Lombardy poplars of Italy). These are the pencil-like accents folks love to grow along the driveway or as a solitary to place emphasis in the landscape. Despite their grave shortcomings (vigorous suckering, weak branches and short lifespan to name a few), they are nonetheless indispensable.

Here in Manitoba large swaths of Swedish aspens and Tower poplars are being wiped out en masse by this disease. It's horrible to watch as the leaves turn a bronze-brown, eventually killing entire branches and finally the entire tree in a few short years. I have witnessed rows of stately upright poplars completely wiped out in two years. There is no known cure or even treatment for this disease, and it is very difficult to control its spread (much harder to contain than Dutch elm disease, for example). Sometimes the trees will recover on their own, but that just seems to be at the whims of fate.

This makes it even more imperative in my mind for plant developers to find or breed improved alternatives to these columnar trees. Columnar cedars are the de facto standard, but we are definitely over-planting them, and they are not nearly as forgiving as the aspens in exposed locations. The fastigiate (pyramidal) English oak is much more common in warmer climates but is not hardy in zones 2 through 4. Dakota Pinnacle birch is similarly columnar when young but appears to broaden with age, and birches are not the toughest trees on this planet.

Keep an eye out for this disease in your area - it is easy to identify from a distance. If entire sections of your tree are turning bronzy brown, it's probably infected. Too bad I can't recommend what to do from that point, short of getting out the chain saw...

- Jim K.