Quaking Aspen (Populus tremuloides) is probably the tree most coveted by homeowners in the Steamboat area.
Aspens are fast-growing but relatively short-lived (20 years) trees attaining heights up to 50 feet. Cold and hardy but with poor drought resistance, aspens grow best in sunny locations at elevations of 7,000 feet and higher. They prefer moist, well-drained soil and good air circulation.
The beautiful white bark of an aspen is very thin and can be damaged by lawnmowers, weed trimmers, and animals rubbing and clawing. When the bark is injured, insects and diseases tend to enter through the wound, which can shorten the life of your tree. A protective covering wrapped around the trunks of aspens for the first couple winters after they've been transplanted to your yard or garden can help prevent sun, wind and animal damage.
If wildlife is a problem in your yard, you might want to protect the tree buds and leaves during the spring and summer with repellent sprays until the trees grow tall enough to be out of the reach of browsing animals.
The best time to plant aspen trees is in the spring. This gives the tree roots all summer and fall to become established.
Aspens reproduce by both seeds and its root system. There are male and female trees, distinguished by the fuzzy catkins (of males) or cottony seed tassels (of females). Often an original "mother" tree is started by seed, then produces many suckers from its root system. These suckers can be a problem if aspens are planted in a yard or garden, but can be a great way to develop an aspen grove in an open meadow.
Aspens are prone to numerous problems including cytospora canker, leaf spot, twig gall fly and other pests. A new product that the Cooperative Extension office has found to be highly effective for insect control on Aspens is the systemic Bayer Tree and Shrub Insect Control containing imidacloprid that lasts all season.
The trees are also susceptible to Marssonina Spot which is a fungus, Marssonina populi, found in fallen leaves and brought on by wet weather and poor air circulation. If the infected leaves are not removed and destroyed they could continue to infect the tree causing defoliation, reduced growth and possibly the death of the tree. A fungicide applied in a timely manner can help stop the spread of this fungus and prevent further injury to the tree.
Aspens are not easy trees to grow and keep healthy, but the rewards of the work they entail are so worth it in all the seasons -- from the glowing chartreuse leaves that burst out in the spring through the continual movement of the trembling leaves as summer winds blow through to the gorgeous yellows and peach fall colors and the beautiful shadows and silhouettes in our winter landscapes. No wonder it's a Steamboat favorite.
Deb Babcock is a Master Gardener through the Colorado State University Cooperative Extension office in Routt County. Questions? Call the CSU Cooperative Extension office at 879-0825 or email to: firstname.lastname@example.org