This article is adapted from a 2020 Alberta Grains webinar presentation from Dr. Breanne Tidemann's early season weed control considerations - 'In the Field' webinar and was created in collaboration between Manitoba Crop Alliance, Saskatchewan Wheat Development Commission, Saskatchewan Barley Development Commission and Alberta Grains.
Early season weed control can be key to optimizing yield and giving your crop a good head start. Even small weeds compete with your crop for moisture and nutrients while also acting as a host for insects and diseases. Controlling weeds while they are small prevents competition with the crop and in many cases improves herbicide efficacy. This is especially true for some of our more troublesome weeds.
1. Scout, scout and then go scout again.
Scouting is the key to early season weed control. This means boots on the ground and getting out to see what is there (no driving by at 60 km/hr viewing the field from the truck!). Effective weed control relies on knowing what you are dealing with. Make sure to move crop residue around as weeds can be hiding under the stubble. Under cold stress, weeds can be purple in colour rather than green. While this can make them difficult to see, it is still important that they are controlled, so it is critical to scout thoroughly. While scouting, pay special attention to:
Which species are present?
It is important to identify weeds by annual, winter annual or perennial to know what management strategy will work best. Winter annuals include stinkweed, shepherd’s purse, cleavers,
downy brome,
Japanese brome, and narrow-leaved hawks’ beard. Control of winter annual weeds is usually most effective in the fall. These weeds germinate in the fall and begin growing again very early in the spring. If control of winter annuals is required in the spring, careful attention must be paid to weed staging and herbicide choice, as many herbicides cannot control larger winter annuals.
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