by BRIAN LOCKHART
A small patch of giant ragweed in an isolated field in southwestern Ontario came to the attention of research scientists when a local crop farmer’s efforts to eliminate it failed.
“This is the first weed that has been confirmed as having a resistance to glyphosate in Canada,” says Dr. Mark Lawton, Monsanto Canada technology research lead for Eastern Canada.
But varieties of the weed have already proven to be resistant to the herbicide in the United States, he says.
Monsanto, an international agricultural products company, created the glyphosate molecule in the 1970s. It is the active ingredient in Roundup, the company’s systemic, broad-spectrum herbicide as well as in other brand name herbicides. The company has also developed the genetic technology to make certain crops resistant to glyphosate applications. In soybeans alone, Roundup Ready resistance varieties now make up more than 60 per cent of Ontario’s annual crop.
Rachelle Byl, horticultural sales specialist at Cardinal Farm Supply in Alliston, says glyphosate represents around 50 per cent of the weed control products they sell to the south central Ontario market.
Giant ragweed is native to North America and can reach a height of three metres if left unchecked. In Ontario it is predominantly found in the southwest.
“It’s a fairly common weed in corn and soybean growing areas,” says Dr. Peter Sikkema, plant agriculture professor at the University of Guelph’s Ridgetown campus.
Sikkema says the farmer contacted the university in the summer of 2008 after noticing he had “poor control with glyphosate.”
The university has researched giant ragweed control in corn and soybean production for several years.
The discovery of glyphosate resistant plants would be a “significant concern to the individual farmer who has it,” Sikkema says, especially if the aim is to control it in a soybean field.
There are good options to control the weed in corn and cereals, such as wheat, he explains: “But in soybeans we really don’t have alternative herbicides that provide effective control to the growers.”
Not all giant ragweed will be glyphosate resistant, he adds. “They are different bio-types. One plant will be susceptible and one will be resistant.”
University researchers have collected seed samples of the weed from 50 locations in the Essex County area, including the location where the glyphosate resistant type was found. Results from this study will be released in about a month, Sikkema says.
Lawton says building diversity into weed management strategy, is a good preventative practice to avoid agronomic challenges. Diversity can be achieved “through several methods including herbicides, tillage, and crop rotation,” he says. BF
Comments
Perhaps all the seed companies that think its wonderful to offer little choice beyond round up ready corn might want to take heed of this development. The southwest US that has had longer exposure to round up ready crops has developed a substantial number of round up resistant weed species. Biotechnology is a terrific advancement but forcing it on growers that don't want it will backfire badly. Exclusively relying on round up for corn and soybeans is a recipe for disaster and giant ragweed is the first of many unless the seed companies forgo short term greed for longer term benefit to the whole industry.
Agree with the earlier comment - biotechnology will backfire as the evidence is starting to show. From the seed companies, you can expect vigorous denial while they continue to focus on short-term gain ahead of long-term sustainability of the industry. But the question there is - where is anyone standing up for the what's really important - sustainability and best practice for health?
hopefully this stops RR wheat from being approved and costing us many markets. RR wheat will not make me money, it will cost money. wheat is the easiest crop to control weeds in already without RR. and so much for underseeding with clover or using .25l of glyphosate to kill the volunteer wheat the next year. I am all for biotech when it put money in a producers pocket but RR wheat must not be allowed.
Is it only the seed companies focusing on short term greed? Seems to me that there is no shortage of producers willing to buy the seed and spray it with roundup. Lack of choice, or good agronomics for producers? If nobody bought the RR seed you can be that the product offering would change pretty quickly.
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