Birch problems

A landscape designer created a plan for my front yard that included a clump birch tree. It was planted at the end of March 2005. The top branches of the tree have continued to look as though they were wilted. I called the nursery, and they sent someone to look at it. They said it was a result of borers. Can a birch tree be saved if the top 1/3 seems to be affected? The leaves on the top are green; they are just wilted. The nursery is willing to replace it, but would the soil be contaminated? They just received new trees from San Diego. These trees have not yet acclimated to Albuquerque, but the nursery said they could replace my tree with one of those. What do you recommend?
- Judy B.

Have you confirmed the presence of borers by finding holes in the bark or a tunneling under the bark? Borers are a possibility, but there are other possible problems as well. Look for signs that the borers are indeed present.

The bronze birch borer is a common birch problem. You didn't say which species of birch you have planted. Some species are more resistant to the borers than others.

If borers are the problem, the tree may survive but may never prosper. The soil will not be infested by the borers. They do not live in the soil. They live in the tree.

I wonder if the problem is that the root system is not able to supply sufficient water to the top of the tree. Since this is a newly planted tree, the root system is limited in size and unable to provide sufficient water for the top of the tree. As the root system develops, more water will be available for the top of the tree.

If you choose to replace the trees, you may want to consider using a different type of tree. Although the birches may grow in New Mexico (especially at higher elevations), they tend to need more water than many other trees and are susceptible to soil and insect problems that other trees may resist. If you want the birch, consider the fact that the white-barked birch is the least well adapted to New Mexico. The river birch and other birch trees with reddish-brown bark tend to be better candidates for growing in New Mexico. All of these require considerable water.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your questions.