Herbicides are one tool for managing cleavers in canola, but there are many other “small hammers” in the toolbox as well.
Seeding rates, row spacing, control timing, and crop rotation all need to be considered, explains Ian Epp, agronomy specialist with the Canola Council of Canada, in this episode of Canola School.
“We can add a few of these small things together and have a net drop in cleaver return to the seed bank, which has a net benefit to the grower over the long term,” he says.
Cleavers can be a winter annual or a summer annual. Like all weeds, they’re are best controlled with they are small, which means glyphosate in fall and/or pre-seed can be effective, notes Epp. Higher glyphosate rates and tank mixes with other modes of action are also recommended to reduce the odds of developing resistance, while considering many cleavers are Group 2 resistant.
In-crop, Epp says they should be controlled early, in the 1-3 whorl stages, which might mean taking the sprayer out twice to control other weeds.
“It’s really important for growers, after they’ve planted their canola, to stage their cleavers and control them fairly early,” he says.
Since herbicide options are limited and the window for controlling cleavers is tight in canola and pulse crops, he stresses the importance of taking a rotational approach to managing cleaver populations and reducing the cleaver seed bank in cereal crop years.
While canola has the ability in the right circumstances to yield well at lower-than-recommended seeding rates, it’s not going to help with managing cleavers.
“Your herbicide has to all the heavy lifting as far as controlling the weeds. If we can bump up our seeding rates, we can actually reduce the amount of cleavers that germinate, that are competitive, and we can actually get a crop that canopies a little quicker,” says Epp.
Find more on controlling cleavers in this CanolaWatch article from the Canola Council.
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