Researchers in Saskatoon are developing a biological herbicide to battle Canada thistle that consists of flax oil, water and selected disease-causing organisms.
Thomas Wolf, a research scientist at Agriculture Canada, and his four-member team have been working on weed control at the centre since 1995 and recently began experimenting with flax oil.
They are targeting weeds such as Canada thistle and green foxtail that have major economical impacts on crops.
The team is trying to develop a way to use oils to keep fungi spores moist as they are applied to crops. The idea is to apply disease-causing organisms that attack weeds, but leave the crop alone.
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Normally, spores need moisture to germinate and infect their targets. That poses a problem given the normally dry conditions on the Prairies. But oils retain moisture and therefore stay on Canada thistle longer than water, which quickly evaporates.
“Flax oil is currently one of our focuses because of our funding (from the Flax Development Commission) but we have an ongoing program that looks at a
variety of oils,” Wolf said.
After isolating a potential pathogen, usually a fungus or bacterium, researchers test it to determine which crops and weeds it attacks and in what environmental conditions it works best.
“Any disease that will cause a desired symptom and gives us the host range we need is a potential candidate,” said Wolf.
However, oil alone might not be the solution.
“We have to keep practical constraints in mind here,” Wolf said. “In some cases, the disease must have water, as oil isn’t a suitable substitute … and we have to remember that producers may not be able to spray a whole tank of oil.”
So researchers are looking for the right blend of water, flax oil and other constituents.
After the ingredients have been tested individually to be certain they do not harm the crop or the disease, the mixture is sprayed on the weed and various crops to see how it affects each.
Wolf is trying to develop a formula that producers can use with standard spray machines.
Although his research is still in its infancy, Wolf believes biocontrol will be an attractive complement to herbicides.
In the end, one group to benefit will be flax producers.
“We are hoping that (the research) helps in terms of the agronomic package that will help maintain and increase yields and the quality of the product,” said Linda Braun of the Flax Development Commission.
“One of our long-term goals is to develop clear weed control recommendations. Anything that is going to help the flax producer be a good steward of the land and maximize his return with flax is worthwhile looking at.”
