This is the first of a biweekly column where I will attempt to address the more common problems of trees, shrubs and woody plants in the Delta County area and provide solutions for these problems.
The Cedaredge Tree Board recently conducted their annual Sick Tree Day where a team of experts visited yards with problem trees at the request of the homeowner.
We visited 24 places in one day — quite an accomplishment, I might add.
As usual, quaking aspens were on the list of trees with problems. Aspens have a plethora of problems, more than most trees grown in our area. According to Colorado State University Extension experts, aspens do not do well at lower elevations where it is hot and dry. Aspens prefer well drained soils that are slightly acidic. Does this sound like our conditions?
They are not long lived trees and in fact in the wild they are succession trees, covering slopes that have lost their vegetation, providing cover until pines, firs and spruces can establish and take over. As these trees grow, they crowd and shade out the aspens, eventually replacing them. Under our conditions, we are lucky to have an aspen stay healthy and live twenty years.
But aspens are desired by many homeowners who love the Colorado mountain look that these trees provide. The good news is that they grow fast, stay relatively small and can therefore fit into smaller spaces and yards. Their bark is attractive, their leaves tremble in the breeze and their leaves have that wonderful golden color in the fall. And to be sure, there are many good looking, healthy aspen trees in our neighborhoods.
I must admit that when I moved to Colorado, I planted five multiple trunk aspen trees in my front yard. But unlike most folks, I reviewed the information on these trees and knew in advance that they could be trouble. I made the decision that I was willing to put up with the tree's many faults and live with the possibility that a chain saw might be the only solution if my trees decided to become terminally ill.
Now what are all the problems that can beset these majestic trees? A short list would include: Cytospora or other cankers that attack the trunk and major limbs, several leaf spot diseases, the poplar twiggall fly, aphids and oystershell scale. Environmentally-induced problems could be chlorosis or leaf margin burn.
Because aspens have problems doing well under our conditions, why not try to improve their chances with a few accommodations. First, try to buy a nursery grown tree. Most trees available come primarily from the mountains. Mountain-collected trees often already have disease and insect problems and are under stress from having so much of their root system lost when they are dug up.
If you must plant an aspen, choose the north or east side of your house in soil that is improved with organic amendment. This will help open up our tight clay soils and allow the tree's roots to breathe. Don't forget to mulch around the tree but not directly up against the trunk. These trees are not xeric plants and need moisture. The mulch will help retain moisture a little longer and keep the roots a little cooler. Don't forget to cage the trees if you live in deer country. Deer can cause severe damage to the tree's trunk with their antlers. Deer will also browse on the lower limbs.
Before you plant an aspen tree you should ask the question — do you really want to plant an aspen? Maybe not if you are unwilling to manage the many possible pests that attack these trees. Maybe not if you can't provide a planting site that improves its health chances. And definitely not if you are unwilling to put up with the suckering habit, especially in lawns and gardens.
That's all for this week. Next time I will continue our discussion of aspen trees, their many problems and solutions to these problems.
Jim Leser retired to Cedaredge after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a master gardener.
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