Issue: September 27, 2003

Removing sprouts on "pollarded" tree

I recently had an olive tree pollarded. It's doing great; however, there are tons of sprouts coming up from the ground around the tree and the lower trunk. Since I want to encourage growth at the top of the tree, I've been cutting the sprouts off. But, I'm tired of doing this by hand every couple of weeks. Is there anything I can do to permanently stop the tree from forming sprouts in these areas?

There are some contact (non-translocated) herbicides that may be useful here. When applied to the new sprouts, they will kill the new growth without entering the rest of the tree and damaging it. However, there is always a chance that the damage will extend beyond the point you desire or that it will not go far enough and will leave the base of the new shoot with its associated buds. These buds at the base of the killed shoot will then grow and the problem will persist. This also happens when you prune off the sprouts. For more information about non-translocated (contact) herbicides, contact your local Cooperative Extension Service agent and explain what you are wanting to do.

The best method of dealing with the sprouts on the trunk is to "glove" them - rub them off with a gloved hand when the sprouts are very young and tender. In this manner, you will remove most of the buds that will form at the base of the sprouts being removed. This must be done very often (the opposite of what you are seeking) but the long-term effect will be more to your liking. The non-translocated herbicide may be more useful for sprouts at the very base of the trunk.

Any time a tree is pruned severely, it is very likely that you will get the response you have observed as the tree attempts to compensate and replace the lost leaf area. If this tree is an older tree, as I suspect it is, then the pruning was not true pollarding. In true pollarding, there is no cutting of growth more than two years old. In proper pollarding, one-or-two-year- old sprouts are cut back to their base. Obviously, this must be repeated at least every other year. Knobs (or knuckles) form at the point to which the branches are pruned back each time. The buds formed at the base of the removed branches are located in the tissue of these knuckles and provide for growth in the following year.

If an older tree is cut back, a similar type of growth will develop, but the process of cutting branches more than two years old is much more damaging for the tree and can create some hazards that don't develop with true pollarding.

Tree wind damage

We had a large Bradford Pear tree damaged by the wind last Thursday. The tree lost two large limbs that basically took out about 1/4 of the tree. Is there anything we can do at the site of the breaks to help the tree heal, or will the entire tree need to be taken out?

Trees were damaged by wind long before we invented wound sealers. Sometimes the damage caused major problems, but usually the plant's own mechanisms took care of the problem. Our pruning sealers and other materials that we smear over wounds have been shown to (at best) be ineffective and (at worst) to make matters worse.

If you feel that you need to do something (more for your sake than the sake of the tree), use a thin, light-colored (white or tan) latex paint. This can "breathe" and is less likely to allow rapid fungal growth under it by holding in excess moisture as do other pruning sealers. If you choose not to cover the wound, carefully clean up ragged tears in the bark with a sharp knife. Give the tree adequate care to allow natural growth of the tree to close over the wound.

If the form of the tree is severely damaged, you may want to replace the tree; otherwise, care for it as described above.

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!