A University of Manitoba instructor is puzzled by a strange weed found last summer in canola fields southeast of Winnipeg.
Gary Martens is hoping to hear from other farmers who have spotted purplish weeds that look like a cross between mustard and canola and do not seem to be killed by Muster or other Group 2 herbicides.
It has some hairs on the stem, but not as many as wild mustard. (Canola has none.) The weed has upright branches, like canola, as opposed to the wide, spreading branches of wild mustard.
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Canola sometimes gets a purple “sun tan” on its south side, noted Martens, remaining green on the other side. This plant is purple on both sides. Its pods are smaller than canola, and its seeds look like wild mustard.
“It could very well be wild mustard,” said Martens. “It is too early to say.”
During six years of scouting fields as a crop consultant for Team Landmark, a chemical applicator based in Landmark, Man., Martens had noticed the weed on occasion. However, this summer he started to pay more attention to it. Other people started to notice it, and see that it was surviving Muster.
In Martens’ experience, the weed has popped up in fields of Hyola, a hybrid canola. But he said the weed is probably not related to a canola variety. The weeds have come from fields that have seen a lot of canola and where farmers continuously used the same herbicide, he said.
Martens gathered seed from a field north of St. Pierre, Man., and from a farmer in Alberta.
He tested some of the seed for fatty acids and glucosinolates and found the composition unique. Now, he wants to count the plant’s chromosomes: “Once we do a count here, we can nail it down.” Wild mustard has nine chromosomes, the threads in a cell that carry genetic information about a plant. Black mustard, another weed, has eight chromosomes, Argentine canola has 19, and Polish canola has 10.
To count chromosomes, Martens will germinate the seed and look at a squashed root tip of the plant under a microscope once the plant reaches the two- to four-leaf stage. But so far, he has only been able to germinate two seeds out of 100 in a growth dish.
The rest of the seeds are dormant, a “survival strategy” of weeds.
Studies show when 100 wild mustard seeds are planted, 48 will germinate at some point during the first year, and another 14 sometime during the first five years. Martens now has the seeds in cold storage to simulate winter, and will vary temperatures to try to coax more seeds out of dormancy.
