A patch of sumac that keeps popping up across a yard is usually not many plants but one plant sharing a single underground root system. That puts the problem below ground, and anything that only removes what you can see leaves the real plant alive.1Virginia Tree Care. How to Get Rid of Staghorn Sumac and Other Sumac Trees The roots can still be beaten, though, by working with the plant’s own habit of pulling food down into them and by patience measured in seasons rather than weekends.
Why Sumac Keeps Coming Back After You Cut It
A sumac thicket is often linked by branching underground runners that send up new stems as they travel.2US Forest Service Research and Development. Rhus glabra, smooth sumac These runners sit fairly shallow, about 3 to 12 inches below the surface.3US Forest Service Research and Development. Rhus glabra, smooth sumac The main roots go much deeper, 7 to 8 feet down, and branch into many smaller roots.4US Forest Service Research and Development. Rhus glabra, smooth sumac The connected stems also share resources, so a shaded stem can be fed by stems in sun, and the parent can feed young sprouts in poor soil.5Acta Ecologica Sinica. Reproduction and community dynamics of staghorn sumac (Rhus typhina) in a coal-gangue area
The stems in a patch are usually one clone, often tallest in the middle and shorter at the edges. New sprouts can appear several feet from the nearest stem, even in lawn or beds. If you dig along a sprout, you usually find a horizontal runner leading back toward the patch.
Cutting is what sets the regrowth off. When a sumac stem is cut, a new shoot usually grows from the first bud below the cut.6Pleasant Valley Conservancy. Sumac Removal Cut at ground level, a dormant bud just above the runner wakes up and forms a shoot.7Pleasant Valley Conservancy. Sumac Removal Cutting the main stems does not remove the root system and can spark even more new sprouts from the roots.8ask.extension.org. Getting Rid of Sumac
The sprouts often come back stronger because sumac stores the sugars it makes in summer in its roots. Removing the top growth also removes the shade that held some buds dormant, which is part of why a flush of sprouts can follow within weeks. Mowing the same spot repeatedly often leaves a dense mat of short sprouts instead of tall stems.
Digging rarely gets the deep main roots, and broken runners can each sprout. Pulling sprouts by hand removes the top but leaves the bud-bearing runner. Cutting is still useful, but as a step paired with treatment, not alone.
Even shredded sumac roots and stems kept the ability to regrow, especially pieces of root.9Springer Link / PubMed Central. Vegetative regeneration capacities of five ornamental plant invaders after shredding Don’t leave chopped root pieces in a compost pile or garden soil.
Make Sure It’s Sumac Before You Treat It
Staghorn sumac leaves are made of many leaflets along a central stalk, and the leaflets have toothed edges.10BYGL | Buckeye Yard and Garden Line. Tree of Heaven vs. Sumac: How can you tell the difference? Its stems are covered in dense fuzz and have firm white pith inside.11BYGL | Buckeye Yard and Garden Line. Tree of Heaven vs. Sumac: How can you tell the difference? The fruit is fuzzy, starting green and turning red, and the fall leaves turn orange.12BYGL | Buckeye Yard and Garden Line. Tree of Heaven vs. Sumac: How can you tell the difference?
Tree of heaven is the usual mix-up. Its leaflets are mostly smooth-edged with a small notch near the base, and its twigs are smooth rather than fuzzy. Crushed leaves smell unpleasant, often compared to burnt peanut butter. Its seeds hang in papery winged clusters, not fuzzy red cones.
Poison sumac is a separate concern. It has smooth leaflet edges and drooping white or gray berries, and it grows mainly in wet, swampy ground rather than dry yards and roadsides. Red, upright, fuzzy clusters point to one of the common sumacs rather than poison sumac.
Using Herbicide to Kill the Roots
Two chemicals do most of the work here. Glyphosate is a nonselective herbicide, so it can injure grass and garden plants as well as sumac if it lands on their leaves. Triclopyr targets broadleaf and woody plants and tends to spare grasses, which helps when sumac grows through a lawn. Products come in different strengths, so check the percentage of active ingredient on the label before mixing.
For cut stumps, painting freshly cut stumps with glyphosate, sold as Roundup, keeps resprouting to a minimum.13Missouri Department of Conservation. Smooth Sumac Control The label suggests a 50 to 100 percent concentration for stumps, but 10 to 20 percent has worked.14Missouri Department of Conservation. Smooth Sumac Control Treat stumps within minutes of cutting, before the cut surface seals.
To do it, cut each stem close to the ground with loppers or a saw. Immediately brush or dab herbicide onto the whole cut surface, especially the outer ring. Work a few stems at a time so no stump sits untreated, and wear gloves and eye protection and follow the product label.
The other option is spraying fresh leaves with a triclopyr-based herbicide in late summer or early fall.15Virginia Tree Care. How to Get Rid of Staghorn Sumac and Other Sumac Trees At that time the plant moves nutrients, and herbicide with them, down into its roots before winter.16Virginia Tree Care. How to Get Rid of Staghorn Sumac and Other Sumac Trees Spraying in spring mostly burns leaves while the plant is pushing food upward.
A foliar spray works best on a calm, dry day so drift doesn’t reach other plants. Wet the leaves without drenching them to the point of dripping. Shorter regrowth is easier to cover fully than tall stems. Avoid mowing or cutting for a few weeks afterward so the chemical can move down.
Which method to pick depends on the patch. Painting cut stumps suits stands with a manageable number of stems, because you handle each stem by hand and little herbicide touches anything else. Leaf spraying suits dense patches of short stems where cutting and painting every one would take too long. Stump treatment can be done in any season the ground isn’t frozen, though it tends to work best in late summer to fall, when the plant pulls food downward.
One treatment is rarely final. Herbicide may not reach every part of a large clone, and killing the tops can still prompt surviving roots to send up suckers. Plan a follow-up schedule from the start.
Protecting Trees and Plants You Want to Keep
Roots of plants of the same species, or sometimes the same genus, can fuse together.17Washington State University Cooperative Extension. Chemical Control for Woody Plants, Stumps and Trees Herbicide, including glyphosate and triclopyr, can then pass through those root links into an untreated plant you want.18Washington State University Cooperative Extension. Chemical Control for Woody Plants, Stumps and Trees Some herbicides, notably picloram and dicamba and occasionally 2,4-D, also leak out of treated roots into the soil where other plants absorb them.19Washington State University Cooperative Extension. Chemical Control for Woody Plants, Stumps and Trees In treated chokecherry saplings, triclopyr and aminopyralid were found in nearby soil, and visible damage nearby matched where herbicide was found.20Weed Science. Herbicides in unexpected places: non-target impacts from tree root exudation of aminopyralid and triclopyr following basal bark treatments of invasive chokecherry (Prunus padus) in Alaska Avoid picloram and dicamba products near gardens, and be extra careful near ornamental sumacs you want to keep.
Damage to a shrub you never sprayed may show up weeks later, so a plant that looks fine on treatment day isn’t necessarily safe. The risk is greatest for plants growing very close to the sumac.
A few precautions help. Prefer cut-stump painting over spraying when sumac grows among shrubs you like, and shield nearby plants with cardboard while spraying. Read the label for warnings about the root zones of trees.
Afterward, watch neighboring plants and stop treatment if you see trouble. Herbicide injury often shows as twisted, cupped, or curled new leaves, or yellowing along veins. Different herbicides cause different symptoms, so the signs help identify the cause but don’t prove it alone. Drought, disease, and insects can look similar, so check whether the damage is concentrated closest to the treated sumac.
Non-Chemical Ways to Weaken Sumac
A common approach is cutting the patch twice in one summer, mid-summer and again late summer, to drain the food stored in the roots.21Pleasant Valley Conservancy. Sumac Removal The first cut, made once the new leaves have fully expanded, catches the plant when it has spent a lot of stored energy on growth. The second cut hits it again as it tries to refill reserves. Cutting in winter, when the plant is dormant, does little to drain the roots. Even so, this double mowing sets the clone back without wiping it out.22Pleasant Valley Conservancy. Sumac Removal Expect to keep it up every year if you rely on cutting alone. Skipping a season gives the roots time to recover, and results can be lost quickly.
Girdling means cutting a ring through the bark all the way around a trunk, which stops food from reaching the roots.23Oregon State College. Control of Undesirable Trees by Application of Herbicides During the Dormant Season The roots slowly use up their stored food while sprouting from the trunk is much reduced.24Oregon State College. Control of Undesirable Trees by Application of Herbicides During the Dormant Season It is slow, usually about three years for a girdled tree to die.25Oregon State College. Control of Undesirable Trees by Application of Herbicides During the Dormant Season Use a saw to cut two rings a couple of inches apart around the trunk, through the bark layer but not deep into the wood. It suits the few thickest stems, not dozens of thin ones.
Goats will browse sumac, but in one trial they nibbled only sprout tips and removed about 10 percent of it, versus 60 percent of a favored shrub.26USDA Forest Service. Angora Goats for Conversion of Arizona Chaparral: Early Results Goats alone are unlikely to clear a patch. Covering soil with clear plastic in hot sun heats it enough to kill weeds,27University of Minnesota Extension. Using the sun to kill weeds and prepare garden plots and tarping can kill roots near the surface.28Phil Hardberger Park Conservancy. Solarization – A Great Way to Combat Invasive Plants But sumac’s main roots run 7 to 8 feet deep, beyond the heated layer, so tarps suit newly cleared shallow sprouts rather than an established clone.
Combining methods works better than any one alone. Cut the patch, then tarp the area to suppress shallow sprouts, and keep mowing any edge sprouts every few weeks to starve the runners. Bag the cut material rather than spreading shreds that can regrow. Expect several years of effort and accept partial control.
Stopping Sumac at the Property Line With a Root Barrier
For aggressive root systems, barriers are commonly set 36 to 48 inches deep, and up to 60 inches for invasive species.29Americover. How to Install a Root Barrier The top should stick up 1 to 2 inches above the soil so roots can’t grow over it.30Americover. How to Install a Root Barrier Sumac’s runners stay within about a foot of the surface, so this depth blocks them.
A barrier makes sense when the sumac is on a neighbor’s land you can’t treat, or to protect a vegetable bed from a planted ornamental sumac. It costs more effort upfront but cuts years of sprout pulling.
Use thick, rigid plastic sheeting or similar material designed for roots, not thin garden plastic that runners can puncture. Thin landscape fabric lets roots grow through, so it isn’t a substitute. Metal sheeting is also used but is harder to work with and may rust over time.
To install one along a fence line, first kill any sprouts already on your side. Dig a narrow trench along the line you want to protect, and overlap and seal the seams so runners can’t squeeze through. Backfill, then check yearly for sprouts that crossed the top.
How Long It Takes to Get Rid of a Sumac Patch
Killing the tops triggers new root suckers, and these must be killed too to finish the clone.31Pleasant Valley Conservancy. Sumac Removal Check the treated patch within a few weeks and spray new sprouts, repeating every few weeks.32Pleasant Valley Conservancy. Sumac Removal Return the next year in late spring or early summer and spray any new shoots.33Pleasant Valley Conservancy. Sumac Removal Repeat in the third year, when there should be few or none.34Pleasant Valley Conservancy. Sumac Removal Buds that stayed dormant during treatment can wake later, which is why sprouts appear after what looked like success.
At each check-up, walk the patch and several feet beyond its old edge. New sprouts are small and soft and easiest to spray while short. Mark spots with flags where sprouts repeat. Each visit should find fewer sprouts; a rising count suggests roots the treatment missed. Write down the date of each visit and roughly how many sprouts you found, and note which spots keep producing them.
Finishing matters because staghorn sumac can change the bacteria in the soil it invades, possibly through chemicals from its leaves and roots.35PubMed. The invasive tree staghorn sumac affects soil N(2) -fixing bacterial communities in north China The ground may favor sumac over other plants for a while after it’s gone. Replant the area with grass or desirable plants once sprouts stop.