How to deal with shoots from tree stumps

Q.   I was alerted to an article you wrote in 2004 about killing off cottonwood and elm tree root shoots or sprouts. I am building a new house in Sarasota, Florida, and had to remove a 50-plus year old Kapok tree of great height and girth, as the roots were growing into where the structure is intended to be. Since the tree itself was removed a few months back, I have now noticed new shoots coming up from and around the remaining root structure. Do you think Round Up or another herbicide (what kind?) would solve the problem, or what do you suggest?

A. The Kapok tree (Ceiba pentandra) is a tropical tree and will not grow in New Mexico, but the answer to your question is relevant for many trees that do grow here in New Mexico. For New Mexico gardeners curious about this tree, it is also known as Java cotton or Java kapok. This tree is actually in the cotton family and the fibers around the seeds can be used like cotton. It grows to be one of the largest trees in the world and has a very extensive root system. Trees in New Mexico may also have extensive root systems that may cause the problems described in the question and may require management to reduce the problems.

There are several products labeled as brush and stump killers that can be used on freshly cut stumps to translocate into the root system and kill a portion of the root system and prevent sprouting. However, since the tree was cut several months ago, chemical treatment of the stump is not appropriate because the tissues required for carrying the chemical into the roots are dead and no longer functioning.

In this case you will need to use a translocated herbicide that can be absorbed through the leaves and thin bark of new shoots. The product you mentioned, Roundup, is one such product. It and other glyphosate-based herbicides may be diluted and used according to directions to be absorbed into the new sprouts and translocated into the roots. Glyphosate are non-selective herbicides that can kill most plants that absorb the chemical.

Other herbicides that will work are those labeled for use on broadleaf plants. They will not harm grass when used properly, but will kill broadleaf plants. This selectivity may be a useful characteristic in your situation. Based on the extent of the root system and size of the tree before cutting, you will need to treat repeatedly whenever new sprouts appear. If this is in a lawn, the selective herbicide may be a good choice. As always when using herbicides and other chemicals in the landscape, be sure to read, understand and carefully follow the label directions.

Gardeners who prefer to avoid use of herbicides in their landscape will find that elbow grease and persistence are effective substitutes. Mechanically removing sprouts as soon as they appear and depleting stored food reserves in the root system will finally result in elimination of the sprouts. This will take some time, but so will the use of herbicides.

In time, as the roots decompose, you will notice the soil sinking in lines radiating from the trunk. The lines of collapsed soil will be most noticeable where the roots were large. This is true of the Kapok tree and other trees. However, this also hints at another method to manage the sprouts from the base of the trunk. You can construct a compost pile over the old trunk of a tree and by maintaining moisture and adding lawn and kitchen wastes, you can speed the decomposition of the trunk. This will speed the cessation of sprouting from the trunk. Do not use herbicides if you wish to use the compost in your garden (some can persist in the compost and cause problems, others will not).

I also recommend that you contact your local Land Grant University Cooperative Extension Service agent for recommendations of products labeled for use in your state. In Florida, you can find your County Extension Service at http://sfyl.ifas.ufl.edu/map/index.shtml (or call UF/IFAS Extension Sarasota County at 941-861-9900, email sarasota@ifas.ufl.edu). In New Mexico, you can find your local NMSU County Cooperative Extension office at http://aces.nmsu.edu/county/.

Send your gardening questions to Yard and Garden, Attn: Dr. Curtis Smith at cwsmith@nmsu.edu or leave a message at https://www.facebook.com/NMSUExtExpStnPubs. Curtis W. Smith, Ph.D., is an Extension horticulture specialist, retired from New Mexico State University’s Cooperative Extension Service. NMSU and the U.S. Department of Agriculture cooperating.