It’s a good year to be a kochia plant.
That should come as no surprise to growers. The tumbleweed-like plant has become a common sight this year, popping up over crop in what seems like larger and more frequent patches, some of which now show less response to glyphosate.
Weather conditions were a large part of the problem, according to provincial weed specialist Tammy Jones.
Kochia fares well in dry conditions, she said, something that Manitobans are well acquainted with this year. Likewise, heat is its friend, and Manitoba Agriculture has noted above-average heat units this summer, including at least one record-breaking week in early to mid-August.
Salinity also promotes the weed, Jones said, and low-lying, high-saline risk areas have become prime habitat.
“It’s more tolerant of salinity than many crops and most weeds,” Jones said. “After a couple of wet years and then you have a dry year that draws down that soil moisture but leaves behind the salts, we have more salinity issues popping up than we have for a couple of years, so then the kochia can take advantage of those spots.”
While she has no concrete numbers on kochia prevalence this year, Jones has noted a distinct uptick in the weed anecdotally across southern Manitoba.
“We’re certainly seeing an intensity that we haven’t seen in other years as well,” she said. “Especially in some of the row crops such as soybeans that aren’t necessarily as competitive, that kochia seems to be really getting ahead of the soybeans. But even in canola we saw it, which is typically a very competitive crop. We’re seeing that there’s still kochia that’s still managing to outcompete the crop. It doesn’t matter which crop you’re looking at.”
Kochia ranked 30th on Manitoba’s top weeds, according to the 2016 weed survey by Manitoba Agriculture and AAFC.
Glyphosate resistance, perhaps one of the greatest kochia-related talking points around the coffee shop this this year, is also on the rise.
Rejean Picard, Manitoba Agriculture extension specialist in central Manitoba, highlighted the issue in a recent Crop Talk webinar.
Picard noted budding resistance issues even in a field without a strong history of glyphosate.
“This area in particular has some issues with that particular weed already, so that’s an area where there’s already salinity and some issues with that,” he said.
Samples from the field tested medium, or likely to develop resistance.
“If the farmer were to continue to grow glyphosate-tolerant crops, there could be come crossing of these different weed plants and end(ing) up with a higher level of resistance here,” Picard said.
Neighbouring farmers had also complained of resistance issues, although no testing was done.
The region is not alone.
Lionel Kaskiw, farm production adviser in southwestern Manitoba, says he sent two kochia samples from south of Souris for testing last fall. Both tested high for glyphosate resistance.
“The issue is definitely something that we’re seeing in the south and west part of the province,” he said. “It’s something that producers are definitely going to have to look at, not only in your chemical rotation, but in the crop rotation.”
Jones expects to update her map of glyphosate-resistant kochia in the coming months. The number of affected municipalities will jump once data is collected, she predicts. Five municipalities had reported glyphosate-resistant kochia as of 2016: the RM of Emerson-Franklin, RM of Macdonad, RM of Grey, RM of Dufferin and the RM of Brenda-Waskada in the west.
Jones, however, cautions that some may assume they have glyphosate-resistant kochia after weeds survive an application, but do not test. In truth, she said, that plant may have emerged after herbicide application or was guarded from the spray by the surrounding canopy.
“Management now will save you a lot of headaches in the future and knowledge is power,” she said, urging producers to test for resistance. “Knowing what you have to deal with just makes a ton of sense as far as I’m concerned. It’s not an embarrassment. It happens somehow or another. Just know what you have so you can manage it better.”
The province has announced a harvest weed survey this fall, which includes resistance testing.