Using sheep to control weeds

After trying for years to kill leafy spurge and buckbrush with spraying, the Permans are using a different approach.

From high in the air, the windswept prairie has a quilted pattern of neatly stitched, 2-acre patches. It is almost as though a giant lawnmower dropped from outer space, its blade set low, grinding up turf and rendering the landscape a visual mosaic.

It was sheep that did it – over a thousand in one flock, chewing through the foliage while sequestered in their poly-wire night pens. Each square in line serves as evidence of their collective hunger from the night before.

It’s weed-control time on the Rock Hills Ranch in Walworth County, South Dakota, near Lowry. Sheep are a new idea for an age-old cattleman’s problem. Lyle Perman has been battling patches of broadleaf weeds on his prairie pastures, as did his father before him, since he and his wife Garnet started their cattle operation in 1976.

sheep grazing

After trying other methods over the years to control big patches of leafy spurge, buckbrush, and other undesirable plants with aerial spraying, spot spraying, and flea beetles, the Permans decided to try a different approach.

“We’re so excited about how well this is working we’re looking at doubling the sheep herd next season - to around 2,000 animals, and maybe cut back on the cows a little,” says Lyle.

Sheep were part of the operation in the early 1980s, but not for weed control, he says. “We brought them in as a diversification for income when we started ranching, but it was really bad timing. Cattle prices were poor, sheep prices were poor, interest rates were high, and then we made the mistake of buying some older ewes, and that didn’t work out very well.”

Sheep are back on the ranch again for diversification of the income stream and because they eat different plants than cattle do, explains Lyle. “We were having problems with a particular forb that’s not native – leafy spurge – and we knew sheep had a history of being a good consumer of spurge, wormwood sage, and others.” 

His concerns about sheep included fencing, predators, and management. Those problems were solved by working with a custom sheep contractor who not only provides the sheep, but also a Peruvian shepherd named Jesus and his crew of dogs. Employed by the contractor, the stocky, smiling shepherd and his dogs are assigned to the ranch for the summer and essentially live with the sheep. 


Astride his four-wheeler, a border collie deftly perched on the deck, Jesus herds the sheep slowly toward water after they are let out of their 2-acre night enclosure. A couple of Jesus’ large white Great Pyrenees dogs amble alongside the flock as protectors. Jesus arrives at the ranch each morning around 8:00 a.m., releases the sheep from their night pen and then takes them to water for a short period of time. Then he herds them to targeted areas during the remainder of the day.

dogs protection

The day pens, made of poly-wire netting, are laid out over patches of broadleaf plants that need to be controlled. Jesus then rolls up the flexible enclosure and moves it to new ground while the sheep are at the water. The night pens are on fresh ground every night. Two-strand poly-wire won’t contain the sheep. Poly-wire netting works best. 

Lyle watches the sheep traverse a steep hill. “The idea of keeping 1,000 sheep contained and protected from predators has always kept me from doing what we’re doing this year,” he says. 

sheep grazing fence

Leafy spurge is the target noxious weed. It’s not as much a problem in other parts of the world, says Lyle, because grazing land outside the U.S. usually supports multiple species. “They’ve got cows, they’ve got sheep, they’ve got goats, and I’m sure that that’s the reason they don’t concern themselves with it because it is a plant that something’s is always eating,” he says.

Luke explains his take on adding sheep to the family’s cattle operation. “I look at the three legs of the stool – the economics (does it make sense financially?), the environmental impact (is it going to accomplish what I hope it does?), and unintended consequences (will there be changes to our work flow, quality of life, and labor availability?).  Those are three things I’m always evaluating on every ranch decision.”

Economics don’t support spraying pesticides all over the ranch, says Luke. “Trying to rid the grassland of everything that cattle don’t eat is default reasoning.” Besides noxious weeds like leafy spurge and Canada thistle, there are undesirable plants like western snowberry and wormwood (sage). “We can approach it like problems that we need to get rid of,” he says. “Or are they resources we’re not using the right way?”

sheep dogs grazing

The broad-scale use of chemicals on the pastures doesn’t fit the Perman’s forage-based environmental goals. They would be using a broadleaf control to take out problem plants while removing many beneficial ones as well. After several years of considering sheep or goats, they made it happen in 2019. “We still use spot treatment of chemicals on certain areas and on certain types of weeds, but from what I’m seeing with the sheep we can scale that back over time,” says Lyle.

Lisa Surber, executive secretary of the South Dakota Sheep Growers Association agrees. “Weed populations like leafy spurge, spotted knapweed, and others have exploded exponentially, because sheep numbers across the West have gone down dramatically since World War II. Those two things are intimately related.” Targeted grazing with sheep can reduce populations of leafy spurge by 8% a year, she says. “That’s making dramatic inroads with the ability to recover that landscape for cattle grazing again.”

Luke looks over the sheep and scattered cattle. “Nature already had things in balance before we stuck our finger in it, so I always wonder what we can learn from how nature works. I’m not the first cattle guy to bring sheep onto his place. There’s always somebody out there that has already tried it and can give you some guidance. Talking to people who are not afraid to try new things is really helpful.”

Garnet Perman weighs in. “Thinking holistically instead of tackling one thing at a time is a better way to look at things. Nature is resilient, and it’ll figure out a way to solve the problem if you just work with it. Nature always wins in the end, so you might as well learn to work with it. That’s part of the message that we’ve tried to tell everyone through our experiences here.”

Sheep are social animals and don’t scatter as much as cattle, says Lyle. The mob grazing technique works well with containment of the sheep in moveable poly-wire fencing. By only grazing a patch of grass for 12 hours, the damage to native plants is nonexistent, he says. “It’s actually beneficial.” The sheep can eat a 100-square foot patch of leafy spurge in a matter of minutes, says Lyle. 


During a pasture tour of the Perman ranch, neighboring ranchers can see the flock chew through a big patch of leafy spurge. The first ewe bites off the tops of the invasive plant, and then following animals nip it lower and lower until there is only a stub left. This allows native grasses to grow taller and crowd out invasive weeds.

Lyle Perman

Lyle leans against the trailer loaded with tour attendees and talks about how diversity affects the end product: his grass-fed beef. “There are a lot of native legumes that are totally destroyed when you spray with a broadleaf chemical – the vetches, the lead plant, and the milkweed that the Monarch butterfly depends on. Spiderwort and goldenrod might not be high in forage value, but they are still plants that are part of the landscape. They’re deep rooted and they bring nutrients up to the surface. We’re not interested in destroying those plants, even though our cattle don’t eat them. The sheep will.”

Garnet tells is like it is. “Grazing management and biological controls have given us way better results than the chemicals have over time. Chemicals might work in a small patch that’s just starting, but once you’ve got a large-scale problem then management is the solution. People might wonder what those crazy Permans are doing now, but it’s gratifying when you see neighbors put in cross-fences. They’ve been watching and seeing what we’re doing.”

Seeing is believing.

Read more about

Tip of the Day

Agronomy Tip: Use Cultural Practices to Manage Weeds

Soybeans in a straight row. Tillage and crop rotation may be useful tools in weed management.

Talk in Marketing