Excessive sucker growth at a tree’s base or along the main stem usually indicates a problem, especially if it occurs on a tree that has not previously put out suckers.
Some trees naturally produce suckers as a reproductive strategy. These include aspen, Canadian red cherry, Russian olive and sumac, which produce a large quantity of suckers if the plant is cut down.
If the sucker-producing tree is not one of these, look for foreign material restricting or girdling the tree, insect or disease organism, and the overall growth rate.
Bracing material originally used to stake the tree upright during planting often is left on the tree, which can restrict the outward expansion of the tree. They also can restrict the flow of water, nutrients, and hormones within the tree’s cambial zone (living layer), which is just under the bark.
Suckers usually grow below the restrictions as the tree tries to replace or compensate for the portion of the tree that is being harmed. Woundwood sometimes grows out and over the restricting material; however, this is most often the exception rather than the rule. Most times the whole tree or a portion of the tree will die as a result of the restriction. If a late spring or early snowstorm occurs, a tree with a restriction will often break at the restricted point.
Excessive sprouting from the roots may indicate a restriction at the base of the tree. Often, burlap or nylon rope was left on the root ball when it was planted. If this restriction is left in place, there is potential for the whole tree to fail and fall down.
If you find restricting material, remove it immediately. If the material is embedded in the wood of the tree, cut as much out as possible without cutting into the tree.
Avoid this problem by removing stakes and braces a year after trees are planted. In windy areas, the stakes and braces may need to be left on for two years. Braces and straps installed on storm-damaged trees should also be removed after two years.
Boring insects also can cause sucker growth in the main branches or along the trunk of a tree. These insects bore out galleries in the living layer of the tree, causing restrictions in the natural flow of the tree’s vessels. The presence of sap or resin, frass (wood dust), or holes in the tree indicate a problem with boring insects. Chemical sprays can be used to kill the pests when they are actively laying eggs, but once the insects bore into the tree, they will not be affected by chemicals.
There also are some diseases, such as cankers, that can cause restrictions within the vascular system of the tree. Cankers can be identified by discolored bark, a sunken area in the bark, “pimples” along the bark, or a wound that does not appear to seal over. Cankers can be difficult to diagnose and a certified arborist should be called to look at the problem.
Sucker growth also can occur if a tree is in severe decline. Check the growth increments of the branches to measure past growth rates of the tree. Declining lengths over the years indicate a declining tree.
Suckers should be cut off as close to the tree as possible. A product that stops suckers, such as Sucker Stopper RTU, can be sprayed on the cuts to inhibit future growth. If you have additional questions, call a certified arborist. To find one, visit treesaregood.com.
Robert Brudenell is a certified master arborist and owner of The Natural Way Inc. Send questions to robert@thenaturalwayinc.net.
