Alberta legislation lists 75 weeds Province could see orange and meadow hawkweed downgraded from prohibited noxious status
INDUS, Alta. — A war has been waged on weeds since farmers first plowed fields thousands of years ago.
Alberta wrote a law against weeds just after it joined confederation, and while the list of 19 troublesome plants has changed, the threats never go away.
“We need to make sure weeds are regulated so they don’t get out of hand,” said Gayah Sieusahai of Alberta Agriculture’s pest surveillance branch.
Some weeds, such as pigweed, dandelion, shepherd’s purse and stinkweed, are not listed in the act anymore because they are so prevalent.
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The act was most recently revised in 2010 with 75 weeds listed.
The weed lists are reviewed regularly. The most recent proposed changes would downgrade orange and meadow hawkweed to noxious weeds while keeping most other types of hawkweed on the prohibited noxious list.
In Alberta, a prohibited noxious weed designation means all growing parts must be destroyed, while a noxious weed must be controlled.
The category of nuisance weeds was removed because there is no way to control them all.
The list includes 29 noxious weeds, which must be controlled to prevent further spread. They include burdock, yellow toadflax, sow thistle and leafy spurge.
Municipal bylaws could elevate a particular type to a prohibited noxious weed.
Many prohibited noxious weeds on the list are not yet in Alberta.
“We put them on the list to keep them from entering the province, but some are here,” Sieusahai told a weed school in Indus June 4.
Many of the prohibited noxious weeds arrived as ornamental plants, said Nicole Kimmel, a weed specialist with Alberta Agriculture.
Some immigrants used them for medicinal purposes or to make dyes.
Kimmel said some troublesome plants resemble native species. For example, giant hogweed can be confused with cow parsnip. It has not been found in Alberta but is growing in British Columbia’s Lower Mainland around Vancouver.
Others are unwelcome because they carry disease. For example, common buckthorn may carry the fungus responsible for oat rust.
Common barberry arrived as an ornamental, but it carries the fungus responsible for stem rust. It was one of the first plants to be placed on a weed list in the United States in 1918.
“It was devastating wheat crops, and we can’t live without wheat,” she said.
The saltlover plant has toxins that can kill livestock. One gram of oxalate per one kilogram of body weight could be fatal in nine to 12 hours. It is a growing problem in the western United States.
For more information, check www.abinvasives.ca/fact-sheets or www.agriculture.alberta.ca/weeds.
