Minnesotans love their maple trees. Maples make up more than 20 percent of the trees in the state. With their bright fall color, fast growth and dense canopies that shade house and yard, what's not to like?
But as our climate changes and new invasive tree-eating insects march toward Minnesota, it might be time to look at alternatives if you're planning to add a tree to your yard next growing season.
Some maples already are struggling in Minnesota, for reasons that aren't entirely clear. When I was answering questions last year at the State Fair's Minnesota Tree Care Advocate booth, one of the most common was, "What's wrong with my maple?" People described trees that should have been in their prime that were dropping branches, not leafing out and showing increasing dieback in the canopy.
While some of this could be linked to improper planting or drought, experts at the University of Minnesota say it's time to break our reliance on maples. If we keep planting maples and a new disease or insect arrives, we could end up with the situation we already face with ash trees. Ashes, Minnesota's third-most popular tree, are expected to be decimated by the emerald ash borer.
Maples are a favorite of Asian long-horned beetles, an exotic pest that moved from the East Coast as far west as Chicago before an intense decadelong effort to eliminate the pest in Illinois beat the bug back to Ohio. The beetle has no natural enemies in this country, and some experts say it has the potential to do more damage than Dutch elm disease, chestnut blight and gypsy moths combined.
So it's a good time to make our urban forest more diverse. The job may be even more urgent in cities: in Minneapolis, a 2005 tree count shows that more than 28 percent of the city's trees are maples.
Here's some options to consider:
Among big trees, the handsome Kentucky coffee tree is underused here. Reaching 50 to 70 feet tall, it's a great statement tree to replace big elms, ashes and silver maples. Look for male cultivars like "Espresso" that have no seed pods; the University of Minnesota has a similar introduction called "Stately Manor" that may be hard to find in nurseries.