By Marilyn Loser
Alamosa’s environment is more challenging than that of Colorado’s Front Range. However, we can learn a lot from the informative “Front Range Tree Recommendation List (FRTRL)”*. It rates trees from “A” to “D” and includes information on water needs, soil, availability and cold hardiness. Only trees that have been observed for 10 years are on the “A” list.
Sharron Harris, Executive Director of the Colorado Nursery & Greenhouse Association, chose a group of Colorado State University horticulturists, landscape architects, municipal foresters and nursery and greenhouse owners to develop the list.
The group's goal was to encourage anyone who plants trees toward a more diverse and resilient plant palette. It considered tree health, not looks. Just as in food crops, a tree monoculture "lends itself to pests and disease more easily," said Harris.
"Colorado is not the easiest place to have a garden or a landscape or grow anything," Harris says. "The tree that gets planted and dies in a year — that's not good for anyone."
I talked with local nursery/greenhouse representatives Ruthie Brown (Alamosa Green Spot) and Stephanie Coley (North River Greenhouse and Landscaping) to find out about their tree recommendations and inventories.
On the FRTRL “A” list is the Tatarian Maple which is available from the Green Spot this year and will be available from the North River Greenhouse next year. There are two specimens of this small tree on Main Street in downtown Alamosa – one in the 700 block by St. Ives and another in the 500 block by the Veterans of Foreign Wars.
Locust trees are popular at both local establishments. Thornless common Honeylocusts (gleditsia triacanthos v. inemis) Shademaster and Skyline rate the “A” list with the caution to wrap young trees to protect the tender bark. The North River Greenhouse also sells the Black Locust ‘Purple Robe’ (robinia pseudoacacia) which has stellar clumps of fragrant blossoms and was beautiful in Alamosa this early summer. It rates the “D” list due to possible borer damage. The few specimens I’ve seen in town don’t display borer damage symptoms such as dead, broken branches. I don’t know if our cold temperatures discourage the pest. Anyone know?
Many people have mentioned to me that our very windy and cool early spring weather followed by very warm weather produced weird tree responses. As I mentioned in an earlier column, my Hackberry and that in Jardin Hermosa Park looked dead when I expected them to leaf out. Stephanie mentioned that their Black Locust trees also leafed out and blossomed late. Perhaps this is a benefit as they might be less prone to early bud freezing with our unpredictable spring weather.
Ash trees are always popular as they grow relatively quickly in Alamosa. The Fraxinus species (which include the Autumn Purple, Patmore, Marshall’s Seedless only earn a “B” list as they are susceptible to a bore which has not yet been detected in Colorado. The Oak Leaf Mountain Ash (sorbus thuringiaca) is one of my favorites and is doing well around southern Colorado according to Ruthie. It only receives a “C” on the list due to limited observation. Trap wrap is suggested for young trees with tender bark.
Canada Chokecherries (prunus virginiana) received a “B”. This is one of my favorites locally and is sold by both nursery/greenhouses. Its leaves start out green and turn purple. The birds love the berries. Yes, it does sucker close to the trunk, but I’m willing to trim it back as I love the purple foliage and graceful form.
A favorite in Alamosa are crabapple trees as they are cold hardy and burst with color in early May when we’re weary of the long winter. Surprisingly to me is the “C” rating for Robinson crabs which indicates the Front Range doesn’t have a lot of experience with the tree. The one is my front yard is more than 30 years old. It has beautiful dark pink blossoms and is less disease prone than the Hopa Crab also found in the Valley. I think due to our cold temperatures, crabapples aren’t very disease prone here.
On the “B” list are native aspen (populus tremuloides) and Swedish Aspen (populus tremula erecta). The North River Greenhouse is now carrying the Swedish Aspen which is more columnar in its leafing habit and has more serrated leaves than our native aspen that tends to have a high crown and bare trunk as it ages. Ruthie doesn’t encourage our native aspen or many other populous species for yards as they tend to sucker. “You see more suckers around town this year due to the stress of wind and drought,” says Ruthie. On the other hand, they are cold hardy and do well at our altitude.
I encourage you to visit our local retailers and plant a tree! We need more.
Street Tree Inventory: About 600 trees were preliminarily inventoried in Alamosa west and south of the Rio Grande, north of Main, and east of Adams State College. The Tree Board is looking for volunteers to walk the sidewalks of their neighborhoods to complete the survey during August using provided forms and guidance. Interested? Please call me at 719.589.3295 or email Marilyn@AlamosaTrees.net. We’d love your help!
*Find the list on the web at http://www.ext.colostate.edu/pubs/garden/treereclist.pdf. For the Alamosa Tree list go to AlamosaTrees.net and click on the Tree Lists tab.
“Will urban sprawl spread so far that most people lose all touch with nature? Will the day come when the only bird a typical American child ever sees is a canary in a pet shop window? When the only wild animal he knows is a rat - glimpsed on a night drive through some city slum? When the only tree he touches is the cleverly fabricated plastic evergreen that shades his gifts on Christmas morning?” Frank N. Ikard, North American Wildlife and Natural Resources Conference, Houston, March 1968