The establishment of the highly destructive emerald ash borer in Minnesota will once again force us to re-evaluate what type of trees we should be planting. When Dutch Elm Disease devastated our urban and native forests starting in the 1950’s the same question was asked since so many communities had planted such large numbers of Elm trees.
The all too frequent answer to this question between 1960 and 2005 was to plant large numbers of ash trees. Seedless Ash varieties were available and ash were easy to grow in tough urban conditions. The results were the over-planting of ash trees, and great vulnerability to another disease or pest.
Planting so many ash trees was simply foolish and ignored the hard lesson learned of Dutch Elm Disease. Our response to the havoc being created by Emerald Ash Borer should be to plant a wide diversity of trees so if/when another devastating pest or disease comes along, we will lose a far smaller percentage of our urban forests.
When considering choices for shade trees, try to get a fairly even balance from the following families of trees: Oaks, Maples. Lindens, Hackberry, Birch, Horsechestnut, Ironwood, Yellowwood, Catalpa, Honeylocust, Ginkgo, Maackia, Aspen, Kentucky Coffee Tree, Amur Corktree, Locust, Willow and the many good new hybrid Elm varieties that are highly resistant to Dutch Elm Disease.
When considering Ornamental trees, try to achieve a balance from the following groups: small Maples, Flowering Crabs, Magnolia, Cherry, Plum, Lilac, Hydrangea, Forsythia, Ninebark, Euonymous, Bleu Beech, Pagoda Dogwood, Hawthorn, Weeping Pea Shrub, dwarf evergrens of various kinds, dwarf or narrow form Birches and Oaks, small Willows and the native Showy Mountain Ash.
As you can see there are plenty of options available in both shade and ornamental trees to help us avoid over-planting of one kind of tree. Be sure to make your choices to the varieties best suited to your particular site conditions of soil type, light availability, drainage, amount of space available, slope, possible pollution, presence of utility lines/other obstructions, and the regulations in your local unit of government.
If finding the right tree seems a bit challenging, you may want to stop by the nursery for some professional advice. Make your mind up to enjoy variety. Viva la Difference!
I am also sharing this post with my web blog for the Northfield News.