Elms: Love 'Em Or Hate ‘Em

By Marilyn Loser

I’m referring to the Siberian Elms of which Alamosa has in abundance. I know some people who love them. One couple planted some on their property after World War II.  They’re very proud of the trees that now shade what was once low scrub.

I hate them. I am constantly pulling up seedlings or cutting saplings that have grown steathily in the Rocky Mountain currant patch or wild rose garden.  In fact, as I write, my hands itch from scratches I got removing elm shoots in the roses.

Siberian Elms (scientific name: ulmus pumila) were introduced in early 1900’s after being collected in the Far East by an employee of the United States Department of Agriculture (USDA). The USDA encouraged planting these elms in shelter belts across the prairies after the Dustbowl days. Its rapid growth and tolerance for drought and cold initially made the tree a great success.

Siberian Elms are sometimes incorrectly referred to as Chinese Elms (ulmus parvifolia). Chinese Elms produce flowers and winged seeds (they remind me a bit of maple seeds) in early autumn. Siberian Elms disperse round seeds in the spring. I’ve seen their seeds totally fill gutters along the 300 block of West Street.

One reason we have so many Siberian Elms is that they do well in our extreme climate.  They resist Dutch elm disease and endure cold, heat, aridity, wind, and poor soil.  So what’s not to like? They have brittle wood and weak crotches, making their limbs susceptible to breakage, especially in high winds. And as mentioned before, they are prolific seeders. It seems every seed that can find a tiny nook with a drop of water happily germinates. Siberians also have a shorter life span that most elm species.

Unfortunately, many Siberian Elms in Alamosa are ugly and unwanted. They spring up in vacant lots and alleys. Without proper care they struggle along looking half alive with gawky, bare branches sticking out every which way.  They also snuggle next to foundations and sidewalks, lifting both.

Of course, there is always at least one exception to a rule.  I’ve come to respect a beautiful elm out of my home office window – it’s to the east so the seeds blow to my neighbors’ yards, not mine.  It’s just outside the fence of Jardin Hermosa, where it gets healthy doses of water from the park’s watering system.  It’s wider than high, is full and is very graceful.  I begrudgingly understand why someone would want one of these trees.

As many people will recall, the United States had millions of elm trees (especially American Elms) arching over “Main Street USA” in hundreds of towns and cities providing cooling shade and softness to the landscape. But by 1970, Dutch elm disease killed between 77 and 100 million trees in the United States (reports differ on the number). Cleveland, Ohio, witnessed the first case of the disease in the US in 1930. 

Apparently the killer arrived in a shipment of logs from France and spread quickly. The mass planting of elms was one of the culprits in their downfall. While the European elm bark beetle is well known as a spreader of the disease, the deadly fungus also spreads underground from the roots of one victim tree to the roots of another. If elm trees were interspersed with other species, the disease might not have been quite so devastating.

This devastation may have started the movement to avoid monocultural tree plantings. Arborists now strongly suggest planting a variety of trees in an area.

So what to do? Much research has gone into developing Dutch elm- resistant trees. In fact, Colorado State University is participating in the Nation Elm Trial. It’s a large-scale, 10-year scientific project to assess strengths and weaknesses of relatively newly developed elm cultivars.

One strong contender in the project is the “New Horizon” Elm (ulmus japonica x pumila 'New Horizon').  The Wisconsin Alumni Research Foundation developed this tree, derived by crossing a Siberian Elm with a Japanese Elm, and patented it in 1994.  It is an upright oval, dense and compact, with a finer textured appearance than most elm species.  It is NOT a prolific seeder, should have stronger branching than the Siberian Elm, and should do well in our climate. We’ll see.  I’m very hopeful.

Since it is a new cultivar ultimate size and zone information isn’t known precisely. The first planting I know of in Alamosa was in December 2008 in the Jardin Hermosa playground.  The tree is doing well, prompting further plantings in Friends Park and Cole Park this year.

I once had a best friend who lived on Elm Street in Denver.
Suburbia -- where developers bulldoze trees, then name the streets after them.” Attributed to Bill Vaughan and seen on Forester Rob Santoro’s car bumper.