ASK THE GARDENERS. Questions & Answers
Q I regularly read and enjoy your question-and-answer column. However, I have never seen anything about olive trees. After seeing the olive groves in California, I wonder if we could grow a tree or two on our own property in South Carolina. It is not important that it bear olives, but it would be nice to have a stately olive tree. Also, is the Russian olive related to the regular olive? Mrs. J.R.
We, too, have seen olives growing, but never delved into their culture, since we cannot grow them outdoors in our area. We recently received an extremely interesting book: ``The Feast of the Olive,'' by Maggie Blyth Klein (Aris Books), and became fascinated with the history of the olive, as well as its culture. A bonus in the book is the generous space given to recipes.
According to Ms. Klein (and our other references), the olive tree will grow in almost any well-drained soil. If you have full sun, and the temperature does not go below 15 degrees F., you can probably grow some olive trees, provided soil drains well. They will tolerate drought, but do best if watered the same as you would any other evergreen. Once established, they are almost impossible to get rid of. Be aware that if the trees produce fruit, it purples anything it falls on. So the trees should be planted away from buildings and recreation areas.
Russian olive (Elaeagnus angustifolia) and autumn olive (E. umbellatus) are no relation to regular olive (Olea europaea, sometimes written O. europa). Narrow, silvery-colored foliage and olive-shaped berries account for the inclusion of the word ``olive'' with these two species of Elaeagnus. Both provide excellent sources of food for songbirds. They survive in all but the hottest areas of the United States.
Q We moved to Atlanta in midsummer, where we now have a home with many evergreens in the yard. During late summer I noticed what looked like spindle-shaped woven bags hanging from branches. Some were moving around. Upon opening them, I found each had a worm inside. They were obviously chewing on foliage. I picked off what I could find and destroyed them, but periodically I find more of them. Is there a safe spray I can use on them?
What you have are called bagworms. Eggs are laid in late summer inside the bag by a female moth, which is almost wingless. The black male mates with the encased female through a hole in the bottom of the bag, which is made of incredibly strong silk, plus bits of evergreen foliage. The female dies after egg-laying.
In spring, eggs hatch and larvae crawl out of bags to begin feeding and constructing their bags, which they move around. Since they are of the Lepidoptera family, you can spray with Bacillus thuringiensis, which you may find in garden stores as BT, Dipel, Thuricide, or other trade names. Read the label to find if Bacillus is listed. It is best to spray as soon as eggs hatch and larvae are outside of the ``parent'' bag. They will probably emerge in May in your area.
If you have a garden question, send it along with a self-addressed, stamped envelope, to the Garden Page, The Christian Science Monitor, One Norway St., Boston, MA 02115.
Doc and Katy Abraham are nationally known horticulturists.