Elm trees, especially the highly persistent Siberian elm, are notorious for producing aggressive sprouts that quickly colonize a yard or garden. These unwanted growths are technically called “suckers” when they emerge from the root system of an existing tree or stump. A true elm sprout is a sucker, an extension of the original tree’s root structure, making it incredibly difficult to eliminate permanently. The frustration of repeatedly cutting these sprouts only to see them return is a common experience.
Why Elm Trees Produce Aggressive Sprouts
The relentless return of elm sprouts is a survival mechanism rooted in the tree’s biology. Elm trees, particularly those susceptible to diseases, possess numerous dormant buds along their shallow, lateral root system. These buds remain inactive as long as the main tree’s canopy produces growth hormones that suppress their development.
When the main trunk or canopy is damaged, stressed, or removed, the balance of hormones shifts dramatically. This lack of growth-suppressing hormones signals the dormant root buds to activate, resulting in suckering. The extensive, shallow root network allows these sprouts to appear yards away from the original trunk or stump, ensuring the tree’s survival.
Physical Methods for Removing Elm Sprouts
Initial management of elm sprouts often begins with simple physical removal, best suited for small, newly emerged growths. Young sprouts can be removed by hand-pulling, ensuring you tear the shoot as close to the root of origin as possible. Tearing the sprout, rather than cutting it cleanly, damages the dormant bud more thoroughly and slightly reduces the likelihood of immediate regrowth.
For larger areas, regular mowing temporarily manages sprouts in a lawn. Mowing repeatedly severs the foliage, forcing the root system to expend stored energy reserves on constant regrowth. However, cutting sprouts will not kill the root system; it is a temporary control method that may even trigger more aggressive suckering over time. Applying a thick layer of mulch or using a landscape barrier can suppress new sprout growth by blocking sunlight.
Chemical Treatments for Stump and Root Suckers
Chemical treatment is the most effective method for achieving long-term control by killing the root system itself. Systemic herbicides, primarily those containing glyphosate or triclopyr, are used because they translocate, or move, from the application site down into the roots. The best time for application is in late summer or early fall when the tree naturally moves energy and nutrients down to the roots for storage, maximizing the herbicide’s effectiveness.
For sprouts with foliage, a foliar application of a glyphosate or triclopyr-based product can be sprayed directly onto the leaves, ensuring thorough wetting but avoiding runoff. To treat a recently cut stump, apply a concentrated herbicide solution immediately, ideally within five minutes of cutting. Applying the herbicide to the outer ring of living tissue (the sapwood) ensures the chemical is quickly absorbed and transported throughout the root system. Note that using herbicides on sprouts connected to a living tree may damage or kill the desirable parent tree.
Strategies for Long-Term Sprout Prevention
Achieving lasting prevention requires vigilance and targeted action against the root system. If the original elm tree was removed, the remaining stump and its root network must be completely killed to prevent suckering. This often requires repeated cut-surface herbicide treatments on subsequent sprouts, gradually depleting the energy stored in the root system.
Avoiding mechanical damage to the surrounding soil is equally important, as nicking or disturbing the shallow roots can stimulate dormant buds to sprout. Exercise caution when mowing, tilling, or digging near the former location of the tree. For persistent problems, an underground root barrier—a physical material buried vertically into the soil—can be installed to contain the root system. Monitoring the area for several years and quickly treating any new growth is essential for breaking the elm’s aggressive suckering cycle.