Sumac species, such as Staghorn (Rhus typhina) and Smooth Sumac (Rhus glabra), are often admired for their foliage but are notorious for their aggressive, spreading growth habit. These woody plants develop extensive underground networks of rhizomes that rapidly send up numerous new shoots, or suckers. Simply cutting down the main trunk is ineffective and often results in a dense thicket of regrowth due to the deep, resilient root system. Complete eradication of an established sumac colony requires a comprehensive, multi-step strategy combining physical removal with targeted chemical treatments to eliminate the entire root structure.
Physical Removal Methods
Physical removal is most practical for young, isolated sumac plants or as an initial step before chemical treatment. For small saplings, manually digging out the plant can be effective, but it is labor-intensive. Careful excavation is necessary because any remaining root fragments or brittle runners have the potential to sprout new growth.
For larger, established colonies, cut all stems down close to the ground using a handsaw or loppers. This action depletes the energy stored in the roots and limits new photosynthesis, though it will not kill the plant. A technique known as “starvation” involves repeatedly mowing or cutting all new foliage as soon as it appears throughout the growing season. By preventing the leaves from producing food, this consistent removal slowly exhausts the underground reserves, but this method may take multiple seasons to be successful.
Systemic Herbicide Treatment
Systemic herbicides are required to achieve permanent eradication because they translocate the chemical throughout the entire plant’s extensive root system. The most effective active ingredients for woody plants are concentrated formulas of glyphosate or triclopyr. Triclopyr is often sold as an ester formulation mixed with oil. These herbicides work best when the plant is actively moving sugars downward to the roots, which occurs during the late summer and early fall before dormancy sets in.
Cut-Stump Treatment
The Cut-Stump treatment involves immediately applying a concentrated herbicide solution to the freshly cut surface of the main trunk. The chemical must be applied within minutes of cutting, before the plant forms a seal over the wound. This ensures absorption into the cambium layer—the thin, living tissue just beneath the bark. Targeting the cambium is necessary for moving the systemic chemical down into the root system to kill it entirely.
Basal Bark Treatment
Alternatively, the Basal Bark treatment is suitable for stems less than six inches in diameter that have not been cut. This technique uses an oil-soluble triclopyr ester mixed with a basal oil carrier, which is applied directly to the bark of the lower stem. The mixture is sprayed completely around the circumference of the stem, from the soil line up to 12 to 18 inches. This allows the oil to penetrate the bark and carry the herbicide into the vascular system. This method is highly selective, minimizing damage to surrounding vegetation, and is an excellent choice for targeted removal.
Managing Suckers and Preventing Recurrence
After the initial treatment of the main plant, the most significant challenge is the inevitable emergence of new suckers from the surviving sections of the root system. The death of the main stem often stimulates the root system to produce a flush of these new shoots. Vigilant post-treatment monitoring is necessary, as the eradication process often extends over two or more years.
Treat new suckers when they are small and have fully expanded leaves. A foliar spray containing a triclopyr-based product or glyphosate can be used, but careful spot-spraying is necessary to prevent drift onto desirable plants. For suckers near sensitive plants, a more precise approach involves wiping or painting the herbicide directly onto the leaves or freshly cut stems.
To prevent new growth from establishing, physical barriers can be installed. Deep trenching and the installation of a vertical root barrier, such as thick plastic sheeting or sheet metal, can block the lateral spread of rhizomes. Maintaining a dense ground cover or consistently mowing the area will also help suppress new sumac shoots over time.
Essential Safety Precautions
Working with herbicides and removing woody plants requires careful attention to safety to protect the individual and the environment. When applying concentrated herbicides, mandatory personal protective equipment (PPE) includes long sleeves, long pants, chemical-resistant gloves, and eye protection. Always read and strictly follow the mixing and application instructions on the herbicide product label, as this is a legal requirement.
Differentiate common, non-poisonous sumac species from Poison Sumac (Toxicodendron vernix), which contains the severe skin irritant urushiol. Poison Sumac typically grows in wet, swampy areas and has smooth stems and white or greenish-white berries, unlike the common red-berried varieties. If Poison Sumac is suspected, professional removal is advised. If contact occurs, thoroughly clean all tools and clothing with rubbing alcohol or a degreasing soap. Cut sumac material should never be burned, as inhaling smoke containing urushiol can cause severe respiratory distress.