The Taming of the Shrew (Aspen)

Column by Carlos Valdez
Cooperative Extension Horticulture Agent
-The Taming of the Shrew (Aspen) … this consummate white barked beauty is difficult to grow in Los Alamos landscapes.

Aspen (Populus tremuloides) are trees with admirable beauty, and it naturally follows that we want our landscapes filled with what we find beautiful.

Unfortunately, try as we might, aspen are not well adapted to domestic landscapes, even here in Los Alamos.

They are short-lived, as expected from their role in forest ecology, and even properly cared-for trees may not reach 20 years.

Aspen transplanted into landscapes are collected primarily from the surrounding mountains.

A few nurseries offer container-grown trees and while these should not experience the same initial stress that wild-collected aspen do, later insect and disease problems are still probable.

Los Alamos property owners who may be considering investing in aspen should be advised that aspen are one of New Mexico’s most pest- and disease-riddled trees.

Aspen prefer the moist, well-drained, slightly acidic soil and cooler temperatures found at higher elevations.

Much of the soil in Los Alamos County is compacted and alkaline.

Aspen transplanted to such soils are at a disadvantage, especially considering that wild-collected trees loose much of their root system in the digging process.  

Aspen in the county are commonly susceptible to Marssonina leaf spot, cytospora canker, oystershell scale, poplar borer, tent caterpillar, bacterial slime flux disease, blotch leaf miner and galls.

These are some of the challenges faced by aspens, many of which have no solution.

It is advised that they not be planted lower than 7,800 feet in New Mexico.

That rules them out for much of Los Alamos County.

There are many characteristics which go into the making of a good landscape tree and suckering is not one of them.

Unfortunately, this is a predominate characteristic of aspen. Their colonizing propensity will most certainly lead to suckering in the vicinity of the tree. 

Meanwhile, the original plantings which were strategically placed are often short lived and tend to decline much sooner than desired.

Despite the numerous seeds that aspenssend floating in early summer, the trees reproduce almost exclusively by vegetative means.

These growth properties make it a much more appropriate choice for large acreages at high elevations where the trees can grow according to their own notions.

Another complaint about aspen in Los Alamos landscapes is that they do not develop as brilliant a yellow fall color as those in the mountains.

Differences in soil chemistry and texture, soil moisture, temperature and sunlight intensity all contribute to this problem.

If you are still bent on planting, or already have the timorous trees, there are several steps to take for bettering their chances.

Plant them in light, well drained, moist soils on the east or north sides of buildings.

Mulch and water well, especially if you are at a lower elevation. Remove diseased or damaged branches.

Remove fallen infected leaves. Remove branches or trees, as needed, to ensure good air circulation. If using sprinkler irrigation, water in the early morning so that leaves don’t stay wet.

Luckily we live in an area where aspen can be enjoyed in all there grandeur. So jump in your vehicles and take a joyride into the Jemez, pack a picnic lunch and take a hike.

For better alternatives, contact the Los Alamos Cooperative Extension Service at (505) 662-2656 or

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