Common burdock was a problem of increasing severity on the Maple Creek, Sask., ranch of Eric and Ann Lawrence, until some sheep came to the rescue.
Burdock is a biennial that reproduces by seed and reaches about one to two metres in height. It thrives in moist habitats such as the two steep and narrow coulees on the Lawrence ranch.
“It has a large, very sticky seed that gets tangled in the livestock’s hair coat, causing an unsightly mess,” said Eric.
“Seeds are then spread wherever the livestock graze. As the seeds break up, particles of seed get into the animals’ eyes, causing irritation which sometimes creates enough injury that it leads to an eye-cancer situation. We’ve had to cull four or five animals every year, which was getting expensive.”
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Each year, the Lawrences spent about six days hacking and burning the mature plants before turning their 200 cows onto the coulees they use as winter pastures.
“It was a filthy job. The stalks are tough and up to two inches in diameter, the burrs get in your clothes, the seed particles are irritating and, no matter how careful you are, they re-seed anyway. It was wicked,” said Ann.
Some producers have successfully used
2,4-D to control burdock, but this is practical only in open coulees with small burdock populations. And the Law-rences raise cattle without the use of chemicals.
In frustration, they turned to their sheep-ranching neighbors, Dale and Dawn Montgomery.
Unlike cattle, sheep will more readily graze broad-leaf plants such as burdock, and easily move through thick brush and up and down steep slopes.
The Lawrences hoped that if the sheep repeatedly grazed the burdock, seeds would not be produced and, over time, the burdock population would drop.
“The Montgomerys were open to the idea, so Dale, Dawn and their Border Collies spent last summer herding about 1,000 sheep through the mile-long coulees. They made two passes, which grazed first growth and regrowth, for a total cost of about $3,000 per year,” said Ann.
Monitoring the sheep-grazing trial and providing a portion of the shepherding cost this year was the Grazing and Pasture Technology Program.
“We are interested in addressing grazing problems in practical ways, then spreading the word,” said Bob Springer, a rangeland agrologist with the program in Swift Current, Sask.
“We also support the concept of multiple-species grazing, which works well in this case because the cattle and sheep have different diets.”
To spread the word, a field day was held in September. The visual impact of the practice was heightened by the grazing-exclusion cages that had been set up to compare grazed and ungrazed treatments. The grazing program will support the project next year as well, said Springer.
Economically viable
Even without outside support, the Law-rences think the cost of sheep grazing would be justified in the short term if it effectively controls the problem.
“From what we can see this year, seed production has stopped. But next year will tell the tale. We stopped the burr infestation in ’97 and ’98, but we won’t know if we have also stopped the new growth of these biennial plants until well into the growing season of 1999.
“Still, we think we are ahead of the game. It was getting worse all the time. Every year, every plant produces 300 to 400 burrs with a zillion seeds in each burr. If you leave them and they get in the hides, the problem spreads across the country.
“Because we’re dealing with a biennial plant, we expected this would be a three-year project. But we’re hoping to see a fairly dramatic difference next year,” said Ann.
