A Greener View: Choosing trees to thrive in specific regions can be tricky
Aug 17,2007 00:00 by Jeff_Rugg

Q: I am trying to find several trees for my yard. I can't find them in the nurseries around town. Can you help me?

A: There may be a several reasons why the trees you are looking for are not at the local nurseries. They may not grow well in your region or they may be difficult to propagate, causing the nurseries to have a limited supply. Some trees are hard to grow or transplant, and are often only available at specific times of the year.

Newcomers to a region usually want to plant certain familiar trees. Sometimes the trees are impossible to grow in that region, and may require an especially good site on their new property in order to maintain tree health. Occasionally, the trees do survive in the region; however, they are such maintenance headaches that nurseries will not stock them in favor of trees that grow well.

For instance, several white birch tree species are native to northern states. They do not easily tolerate heat in the summer, since they are native to cooler climates. The farther south they are planted, the more water is needed; they should be planted along the edge of a lake or stream if grown where the summer temperatures reach the 80s or 90s on a regular basis.

When deciding on a tree, many people have a specific feature of the tree in mind. White birch trees have white bark, making a pretty ornamental tree. In warm climates where the birch won't grow, a substitute for the white bark would need to be found. A sycamore might work; however, it grows much larger than the birch, and also has a higher maintenance cost as it loses large pieces of bark and develops the white trunk. Another substitute could be a crepe myrtle. It is much shorter than a sycamore or birch and its bark is not as white, but it does have pretty flowers.

It is rare that you will find a tree that is a perfect substitute for another tree. The closest substitute will be one from the same family of plants. In the case of the white birch, there is a Japanese birch that tolerates warmer temperatures than the North American birches, but is still not a good tree for the southern United States.

Most urban locations have an ordinance specifying the types of trees and their locations in the landscape. The list of recommended trees is sometimes very limited, which leads to serious problems when a pest or problem affects only that kind of tree. Many cities were stripped of their elm trees when Dutch elm disease came along. A similar situation is occurring in the Midwest with the emerald ash borer killing ash trees. Some municipalities have a list of trees that are not allowed; it may be an important list to see.

Check with your local nurseries to see why they don't have the specific trees you want and what trees they would suggest as substitutes. You will be better off planting trees that are best suited for your region. If the trees you want are only partially suited, you may have to be careful in choosing the right site for them to grow, or else you will be in for a lot of maintenance trying to keep the tree healthy.

Q: My pecan tree, which I believe produces Stuart pecans, loses limbs every year. The leaves fall off once it becomes heavy with leaves, pecans and rainwater. Many limbs are bowed under the weight now.

Do you have any thoughts on the matter?

A: Some pecan growers actually shake their trees to get some nuts to fall off early so the trees don't have broken branches later, but this is impractical after the trees become larger. There are several stress-related problems that cause trees to loose branches or nuts early. It can be a water-related problem where irrigation could help. Or it could be due to deficiencies in specific micronutrients such as zinc.

Another common problem for many trees that lose small branches is an insect called a twig girdler. If the branches falling off look like they have been neatly pruned, the insect could be the problem. Squirrels also nibble on branches, causing the ones heavily laden with nuts to fall. Have a licensed arborist take a look so he can determine the exact cause.

E-mail questions to Jeff Rugg at info@greenerview.com.

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