Issue: November 15, 2008

Storing dahlia roots over winter.

Question:

I have a question about a small maple tree in the middle of our yard. I do not know if you can help with an answer, but I certainly appreciated your earlier advice about a honeysuckle. The leaves of this maple tree are yellowish and have brown all around the edges. The lower or central trunk of the tree has bark that is peeling, but the bark on the main branch looks fine. However, the leaves are as browning as described. Any thoughts on whether or how the tree might be helped?

Karen K.

Answer:

Most maple trees (sugar maple, Japanese maple, and others) will develop the symptoms you have described because they are best adapted to acid soils and more humid air. The calcareous (alkaline) soils and dry, frequently windy, conditions in New Mexico result in leaf scorch by mid to late summer.

Even if you keep your maples well watered, you can often not prevent the browning of the leaf margins. Our water contains high levels of dissolved solids (mineral salts) that can cause salt burn.

The peeling bark you described may just be the natural process of bark development if it is peeling in long vertical strips with new bark underneath the strips. This is a normal condition for silver maple trees. This maple has a silvery bark on the branches and silver-gray bark on the trunk. The leaves are fairly large, typical star-shaped maple leaves.

You can try to help by acidifying the soil, but in New Mexico that is a short-term solution, and in some areas not feasible because the soil contains so much calcium to ÒbufferÓ (prevent) changes in soil acidity. Even in places where you can benefit from acidification, the effect only lasts one to two years. You can try acidifying the soil by applying agricultural sulfur and watering it well, or using commercially available soil acidifier products. Apply these products at the recommended rates (do not make it stronger than recommended) and treat the soil at the treeÕs drip line and outward. Do not apply it near the trunk of the tree.

Another solution is the replacement of the tree with another tree that is better adapted to the growing conditions provided in New Mexico. There are some excellent trees that can provide fall color without the leaf scorch problem. These include the Texas red oak, Shumard oak, chinquapin oak, Chinese pistache, Raywood ash, White ash, and if you really like maples, the bigtooth maple that is native to some parts of New Mexico. Dr. Ralston St. Hilaire at New Mexico State University has been working with selected varieties of bigtooth maple to select those best adapted to our conditions and to make them available through the nursery industry. This is only a short list of potential fall color, shade trees for New Mexico. If a gardener chooses one of these trees, the cultivar should be one known to provide consistent color under our conditions. Look at trees growing in your community and ask which cultivars are producing the best color.

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 question!