Tools for Cleaver Management in Canola

Cleavers are quickly becoming one of the top weeds of concern in canola crops in western Canada. It is estimated that Cleavers are the number 3 weed in canola, and there’s increasing concern that they are developing resistance to certain in-crop herbicide groups, eventually including glyphosate. Cleavers are very competitive in canola and their seed size and shape are very similar to canola so they can cause significant reductions in grade. A spring pre-seed glyphosate application is the most effective way of controlling winter annual cleaver populations, before they advance too much to be controlled in crop. Higher rates of pre-seed glyphosate are required in order to control larger winter annual cleavers.

Controlling summer annual cleavers is a different story; they tend to emerge right after the crop is planted and may grow large too quickly to be controlled by in crop herbicide applications. In the past some growers have fall applied residual products, such as Edge, to help control cleaver populations. Due to weather conditions this fall, fall herbicide applications were difficult to make, however there are some different management strategies.

In 2012 and 2013 the University of Saskatchewan conducted research regarding Cleaver control in canola. Their results showed that pre-plant applications of glyphosate and certain tank mixes followed by standard in-crop herbicide applications provided good control of cleaver populations, usually greater than 85-90%. One of these tank mix options is, Command Herbicide, a newly registered soil applied, pre-emergent, residual herbicide for early season management of Cleavers in canola. Its active ingredient is clomazone, the only registered group 13 herbicide in western Canada, which is great for resistance management. Command can be used in front of any herbicide tolerant canola system. “It is your first line of Cleaver control in front of canola,” said Nolan Kowalchuck, Account Manager for FMC Agriculture products in Alberta. “You can expect up to 4 weeks of residual control for your canola and because Command is a group 13, a new mode of action, it is an additional tool in the battle against herbicide resistance.”

Control tips:

• If possible control cleaver populations the year before you seed canola. In cereals there are some good options for in-season cleaver control.
• Fall glyphosate applications are an important control method if you have heavy populations of winter annual cleavers.
• Whenever possible, add a different herbicide group to your pre-seed glyphosate applications, that targets cleavers, resistance management is becoming more and more important.
• If you are straight cutting your canola, pre-harvest or harvest aid applications can also help control cleaver populations.