1 - Tree of Heaven is not a desirable landscape tree and takes some effort to remove if it invades a landscape.

Q.

Do you have any recommendations for treatment to manage Tree of Heaven in an Albuquerque yard?

- Judy O.

A.

For gardeners who do not know this tree, Ailanthus altissima, or Tree of Heaven, it is a tree to avoid. It is weedy because it spreads rapidly and out-competes other plants. Management is easiest if it is not in your garden. Management is still possible once you have it, but the earlier you begin dealing with it, the easier it is to eliminate or at least manage.

This tree has large, odd pinnately compound leaves that look like gigantic pecan leaves. The leaves release an unpleasant fragrance when crushed. The stems of this tree are very weak and have a large pith. The tree produces numerous seeds with large, corkscrew-shaped wings to help them disperse and start new trees. These trees are also able to reproduce themselves from sprouts produced by adventitious buds that form on their roots. The tree grows rapidly even in difficult environments and out-competes more desirable plants. These are the characteristics that give it the designation "weed".

When managing this plant, the first line of defense is removal of seedlings before they can establish an extensive root system. Physical removal of seedlings and established trees is effective, but must be repeated as new sprouts form from the stump and develop from the roots as well. All new sprouts should be removed as soon as they develop. By quickly removing sprouts you will eventually deplete the stored food reserves in the extensive root system and the tree will gradually begin producing fewer and fewer sprouts. By removing the tree and sprouts, you will prevent development of seeds and new plants from seeds.

Sprouts may be treated with herbicides as they develop or may be physically removed by digging or cutting them below the soil line. If you choose to use herbicides, choose a product labeled for managing broad-leaf weeds. Apply the product according to the label directions. Once method you will find on the label of some herbicides is "frill application". In this treatment you will apply the herbicide without dilution into numerous cuts just below the bark into the phloem and cambium tissues. Phloem is the vascular tissue that carries materials from the top of a tree downward to the roots. By using this type of treatment, you will be applying the chemical only to the target plant and not to other elements of the environment. This treatment also increases the efficiency of the treatment by putting it where it can translocate most deeply into the root system and more quickly cause depletion of stored food reserves needed to produce new sprouts. Multiple treatments or multiple physical removals of sprouts will be needed. Persistence and frequent treatment will be required. Without persistence, you will have little success managing this weedy tree.

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.

Links:

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook page.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!