Waxy covering on leaves?

What is the waxy substance on the top of leaves? - Linda F.

The waxy covering on plant leaves, young stems, and fruit is called the "cuticle". It is composed of cutin, a wax-like material produced by the plant that is chemically a hydroxy fatty acid. The purpose of this covering is to help the plant retain water. In arid regions, that is very important. In wetter regions, the waxy coating may help prevent infection by disease organisms. The waxy material may exist in the form of flat plates, or a mass of threads. It may be loosely formed, allowing easy passage of gases and water vapor, or it may be tightly formed, interfering with gas exchange.

In some plants, the waxy coating causes a bluish coloration. This bluish coating of wax can be rubbed off, leaving a greener appearance. It is this waxy coating that causes a blue spruce to appear blue.

More information is available in books on botany and plant physiology. Such books should be available at your local library.

Removing roots from old hedge?

What is the easiest way to remove roots from a large hedge that has been in this location for 10 to 15 years? Would you recommend poison (DDT) or drilling/grinding/digging roots away? - Tony

The method used to remove the roots from a long-established hedge depends on the type of plants and the nature of their roots. It is a good idea to remove them if the roots are very large and from a plant likely to sprout from the roots. You may find it just as effective to dig up the stumps and large roots surrounding them with a shovel or backhoe. Finer roots systems or roots that will not sprout may be left to rot in place unless the site is needed for planning. Even then, only digging in the area needed to plant the new hedge or flowers must be cleared of roots. An herbicide may be used but should be used carefully and according to the label directions. Roots may remain for a few years. Even then, the roots will remain in the soil and interfere with new planting. By the way, DDT was an insecticide, so it would not have killed the plants even when it was available. However, DDT is no longer available and is illegal to use. Perhaps you meant 2,4-D. This herbicide would work, but it may create difficulties if you apply it to the soil and if you plan to plant a new hedge in the same location. That is why it is important to read the label directions and follow them closely.

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!