The scientists also try to determine which part of the plant is best to attack: The seeds, to prevent new plants from taking root, or the roots, to kill the plants outright. The insects are screened to make sure they don't eat related plants or destroy agricultural crops. Testing has become more stringent, officials say. And now, American scientists are finding that a weevil released in the late 1960s to control nodding thistle is attacking some native thistles. Instead, the toads became a national blight. Australia introduced cane toads in 1935 to eat a type of beetle that was destroying sugar-cane fields. Gypsy moths were brought to North America a century ago to buoy the silk industry.
LEAFY MS AGENT FREE
"Science has improved, but the weed problem hasn't, simply, I think, because we have so much transportation and so much free access," she said.Īlong with the growing concerns about the impact of non-native weeds, there have been some eyebrows raised about introducing foreign species. has a list of 21 noxious weeds that require control under legislation, the problem seems to be getting worse, Ms. DeClerk-Floate's work.Īs hound's-tongue and other weeds progressively infest the province's rangeland, fewer cattle can be supported, said Elaine Russell, a spokeswoman with the B.C. Ranchers, land owners and environmentalists are among those closely watching Dr. Hound's-tongue can be toxic to cattle and horses, hinders other plant growth and affects natural water reservoirs. So far, the European weevils are wiping out the tall flowering plants on plots where they have been released, according to Rose DeClerk-Floate, the lead researcher on the project, also based at the Lethbridge facility. The voracity of the Mogulones cruciger, or root-feeding weevil, is currently being tested in B.C.'s East Kootenay Valley against this foreign weed. Among the up-and-comers is hound's-tongue in British Columbia's southern interior and Alberta's foothills. Major concerns now include knapweed and leafy spurge in Western Canada and purple loosestrife, which has swept like wildfire across the country. Nodding thistle is being controlled by using seed weevils, while root beetles have gobbled up tansy ragwort and St. These projects have primarily been conducted through the federal agriculture agency and there has been some notable success. Since 1952, more than 70 exotic insect species have been unleashed from coast to coast in battles against 21 types of weeds. "What we're trying to do is re-establish that predator-prey relationship and get control."
Bourchier, who is based at the Lethbridge Research Centre in southern Alberta. There's a suite of herbivores that are feeding on them," explained Dr. "Most of these plants are not problems in Europe where many of them come from. All this has spurred the search for the best foreign insects, known as biological control agents, to contain the spread of foreign scourges. Spraying massive tracts of rangeland may not be practical and there are concerns about chemicals getting into the water as well as the impact on non-target organisms. Leafy spurge is among an increasing number of weeds taking over Canada's landscape by crossing borders with ease in an era of global trade and transport. "We're trying to get it established in each municipal district in southern Alberta over the next three years and then use those sites, as we get them established, for redistribution to ranchers," Dr. Scientists plan to let loose 270,000 beetles here this year to see if they can control the spurge population. As it infests meadows, it is preventing some butterfly species from colonizing. This yellow-flowered weed, which can grow to a metre in height, is muscling out plants on pastureland where cattle graze. That's good news for ranchers as well as native flora and fauna. "We're getting very good results," said Rob Bourchier, referring to the Aphthona lacertosa, a European black beetle, which has caused visible damage at 80 per cent of monitored sites since it was released four years ago. Now, a scientist at Agriculture and Agri-Food Canada thinks he has finally found the bug that's up to the job. Fourteen species of foreign insects have been released in Alberta since 1965 with a mission to munch their way through leafy spurge, a noxious European weed that infested the province 80 years ago.