Frequently I am asked by people living in newer neighbourhoods, "What trees should I plant?"
With the well-known problems of American elms with Dutch elm disease, the impending issue of ash trees being killed by emerald ash borers, as well as columnar tower poplars and Swedish aspens dying by the hundreds from infestations of poplar borers and poplar fungal canker diseases, people ask: "What else can I plant that is going to stay around and be healthy for a long time?"
One of the trees I definitely recommend are the varieties of linden trees. I have a Little Leaf linden in my yard, and the city has been planting many Dropmore lindens on boulevards and in parks. Occasionally I see Green Spire linden, too. At this time, lindens do not have any significant issues.
All lindens have a pleasing symmetrical shape. Many lindens, except those with a spire-like shape, look like large beehives. This makes them ideal for formal European gardens where symmetry and perspective over longer distances is important.
Linden and its other related cousin tree, the basswood, are members of the botanical family called Tilia. Linden trees are highly adaptable to grow on clay-loam soils, which typically occur in most urban areas of southern Manitoba. The smaller leaf lindens grown in Manitoba were originally selected from European trees.
For most yards, a little leaf linden would be ideal. The indigenous, or naïve linden, is the basswood. This tree grows very tall (there are basswoods here more than 30 metres high). This is definitely not a species for a small city lot.
Any tree, where care practices have been ignored, will have problems. The linden is no exception. The thin bark of linden trees makes them susceptible to damage from mowers, vehicles and rabbits, especially when the trees are young. The bark should be protected with a removable sleeve tube or wrapping during the winter, up to a snow height of at least a metre from the ground. Rabbits will crawl along the top of piled snow and feed on the thin bark to get at the sweet frozen sap.
As I said before, I have not encountered any significant fungal or bacterial disease damaging or killing lindens.
If the bark has been damaged, it must be sealed with an approved pruning tar or tree wound dressing. Insects are not usually an issue on these trees, but if the tree has been placed under stress from some other cause, such as digging into the roots, infestations can occur. The most common of these are scale insects, whose small oval hump-like bodies are often strung out along the twigs like dark pearls.
If you have seen these insects — fortunately they are not too common — there are two strategies you can employ to deal with them. Right now, they can be wiped off with a cloth or even your fingers.
The second strategy can be done next April by spraying a horticultural dormant oil (typically in mid-April) on the buds, twigs and branches before the leaves appear in May. For scale pests in larger trees, you might have to call a licensed pesticide applicator to do the spraying higher up.
So if you are looking for a tree to add to your garden or to replace a tree that has died, think of the lindens. They are a beautiful tree.
Over the years I have made a number of suggestions for planting different kinds of trees. Please contact me if you want further ideas for new trees.
Michael Allen M.Sc.F., RPF (ret’d) is a consulting urban forester, tree diagnostician and certified arborist. He owns Viburnum Tree Experts. He can be reached at 204-831-6503 or 204-223-7709. His website is treeexperts.mb.ca