Tag Archives: trees

Is a new tree on your wish list?

Not all gardeners enjoy reading seed catalogs.  If you are more interested in planning for a new tree then here are a few resources to get you started.

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Aspen Suckers – Persistence Pays!

For many years, my property line was bordered by a small patch of aspen trees planted by a well-meaning neighbor. They were lovely for a few years but despite good care, things began to change – fungal diseases, insects and visible cankers, anemic fall color, as well as “gifts” in the form of aspen suckers peppered both lawns. While I’m not a lawn zealot, these suckers can rather quickly turn into a mini grove of trees as aspens reproduce by sending up shoots from the root of the mother tree. Suckering sometimes indicate that mom is on the decline, which in this case was true.

In early spring 2014, the owners decided the aspens were beyond saving and they removed the ten year old trees. With the trees gone, the  suckers continued to sprout with a vengeance, as the remaining underground root stock tried to offer us replacement aspens.

To win this battle, before every mowing (and sometimes more often) we diligently removed the tender new shoots and their roots by hand and dabbed freshly cut larger suckers with a product recommended by our local garden center (look for active ingredient Ethyl 1 Napthaleneacetate). Ideally, we would have tackled this without chemicals, but in this case, we were advised to go this route. Additionally, we aerated the lawn and over-seeded the grass to make it healthier and thicker, hence more difficult for suckers to emerge. To discourage sucker production, we were vigilant about not over watering.

I am proud to say that this year our persistence has paid off. We’ve not had a single sneaky shoot in the lawn or adjacent garden bed, even with this year’s abundant moisture. The remaining root stock appears to have died out, so (fingers crossed) the suckers are gone for good. For more info on reducing tree  suckers and seedlings: http://www.ext.colostate.edu/ptlk/1538.html

Our experience is very common. Aspens are beautiful in the mountains, but ill-suited for the urban landscape. At lower elevations they are frequently disease prone, insect plagued and short lived. Since they thrive in moist, well-drained and slightly acidic soil and at higher altitudes, the Front Range soil, which is predominately compacted, alkaline and clay, is just not ideal.  If you already have aspens on your property, here is information which may help you keep them at their best: http://www.ext.colostate.edu/ptlk/1701.html

If you are thinking of adding trees to your front range landscape, check out this list of tree recommendations from Colorado State University http://www.ext.colostate.edu/pubs/garden/07418.html

Written by Linda McDonnell, a Denver County Master Gardener since 2013

One Less Ash Tree for Emerald Ash Borers

yellow tree leaves
When I planted a white ash tree about 10 years ago, I never dreamed I’d be chopping it down while it was still healthy. But I did just that earlier this season and took the loppers to the tree while it was sending out new leaves.

I decided to take action now instead of waiting for the Emerald Ash Borer (EAB) to take it out one day in the future.

It wasn’t an easy decision. I liked this tree a lot, especially in the fall when the leaves turned a brilliant yellow. But it’s only a matter of time before the dreaded EAB makes its way into my landscape and forces my hand.

The tiny Emerald Ash Borer has already caused the death or decline of tens of millions of ash trees in at least 20 states and now it’s in Colorado.

I chose to remove the tree this season to avoid my limited options in the future. Like other ash-tree owners, I’d have to decide whether to budget for the expense of treating a taller tree with insecticides every one or two years to prevent EAB damage or wait for the borers to kill the tree slowly and then hire someone to remove it for me.

Now that this ash tree is gone, I can take my time and find another kind of tree to replace it.

Then I’ll be able to focus my preventive efforts on the much larger ash that shades most of the front yard. That tree is more valuable and will be worth the cost of treating it, once the time comes.

Right now, home owners and urban foresters in and around Boulder are trying to make the same kinds of decisions. They’re deciding whether to treat their trees with insecticides — while weighing the costs with the environmental hazards; measuring the effectiveness with ease of application.

If you have ash trees on your property, you’ll have to make similar decisions in the future, too. Now’s a good time to start thinking of what you’ll do once the EAB invades your landscape. Would you remove a healthy ash tree as a drastic measure to prevent EAB in the future?

There are some good resources to help you decide, including CSU’s Department of Bioagricultural Sciences and Pest Management website and the Colorado Department of Agriculture EAB website that includes an Ash Tree Zone interactive map and a way to sign up for the EAB newsletter to stay informed.

By Jodi Torpey
A Denver master gardener