While most pastures across Saskatchewan were blanketed with snow this past winter, the landscape will change quickly as warm weather arrives. Native prairie plants such as northern wheatgrass and needle-and-thread will soon spring to life, however their undesirable counterparts, such as leafy spurge, will too.
Leafy spurge is a perennial invasive weed many farmers and ranchers are unfortunately all too familiar with. Listed as a “noxious” species under the Saskatchewan Weed Control Act, producers are legally obligated to control leafy spurge, which is incredibly aggressive in pastures, hay land, wetlands, creeks, and ditches. Left uncontrolled, small patches quickly become large, continuous, thick infestations which choke out desirable forage, resulting in reduced productivity and impaired ecological function on entire landscapes.
Leafy spurge has a few key features, including showy yellowish-green bracts, milky sap, and waxy leaves. When the seeds are mature, the seed pods can shoot new seeds up to fifteen feet from the plant, and its root system extends down thirty feet. Because it is so tenacious, leafy spurge usually can’t be controlled with a single type of management, but rather a combination of many control measures.
Grazing is one control option that has great potential. Leafy spurge is a highly nutritious plant, and one that sheep and goats readily eat. Stuart Chutter, a producer and contract grazer from Melville, SK, has experience shepherding large herds of sheep and goats in prairie community pastures in order to control leafy spurge.
“Last summer, we ran 4,000 sheep and goats – in two flocks – to cover the land twice over,” Chutter explains about a recent leafy spurge control project in a community pasture. The timing of grazing is important to set the spurge back and drain down the plants’ energy reserves, he added.
“You want to graze spurge twice, preventing it from going back to seed,” he says. “Graze it early in season then hit it before it flowers again. This decreases the seed bank so there are not any new seeds being dispersed,” Chutter says. It’s been a learning opportunity, saying that they grazed the same pasture with a herd of 1,600 just once in 2016, and found that they had much better control in 2017 and covered more acres.
Herding sheep on a large prairie landscape can be unpredictable. “Herding was described to me as when you go out every morning and you’re kind of like what disaster is going to happen today? Or what adventure?” Chutter laughs. Each morning, Chutter or another herder would use a quad and a couple of dogs to lead the sheep to a specific spurge infestation. Each evening, around supper time, as the sheep started bunching up, they would bring the flock back to their night pen, or build a new pen for them using portable electric fencing. This reduced predation issues and also ensured they covered the pasture adequately.
“There is a large problem with leafy spurge across Saskatchewan and sheep need to be part of the solution,” Chutter says matter-of-factly, but acknowledges there are a few obstacles. Herding is very labor intensive and challenging, and it can be hard to find people willing to spend their entire summer herding sheep. Sourcing sheep suited to a contract grazing project can also be tricky. Finally, producers are often able to access funds for chemical control, but funding is harder to secure for contract grazing. “A balance needs to be struck in order for it to be feasible for a herder and affordable for a landowner,” he says.
Other control options also exist for leafy spurge, and using a combination of options is best. Chemical control is useful, depending on soil type and location of the infestation. Cultural control, like mowing, bagging and burning, can be very helpful in reducing the vigour of the infestation, especially for smaller infestations that require strategic control, such as along right-of-ways or roadsides. Biological control, like leafy spurge beetles, which feed on and weaken the root systems of the weeds, can also be helpful, particularly as the beetle population regenerates each year.
“Spurge is a nasty beast and takes a long-term commitment and a multi-disciplinary approach – spraying, grazing, biocontrol,” Chutter says. “Finding success in controlling spurge is really a long process. One year isn’t going to solve a spurge problem but I think over time we are seeing significant changes in the landscape of grazed land versus ungrazed land,” he says.
— Article supplied by Saskatchewan Prairie Conservation Action Plan
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