Weed control window closing

Rain has set back weed spraying. Early canola crops are near the end of their spray windows, even though some fields have not received a first pass and some fields got a first pass but need a second.

Label application windows:

Glyphosate: Anytime up to and including the 6-leaf stage of canola.
Liberty: Cotyledon stage up to the early bolting stage of canola.
Odyssey/Absolute: 2- to 6-leaf stage of canola.

Herbicides applied after the approved crop stage could cause early flowers to be aborted. (Click here to learn how.) Growers are advised to assess what will create the greater losses — weed competition or loss of the first set of flowers? Canola typically produces more flowers than it can support. The plant can produce more flowers to compensate for early flowers that were lost, provided stress later in the flowering period does not limit this ability.

Aerial application may be required to spray within the application window if fields are too wet for the ground rig. Avoiding ruts is an additional benefit. Click here for aerial spraying tips. Note that Centurion has received emergency registration for aerial application on canola for 2011. For more information, click your province for a link to your guide to crop protection: Alberta Saskatchewan Manitoba

Minimize ruts with ground rigs. If you plan to use the field sprayer, wider tires and lower tire pressures can improve sprayer flotation and reduce rut depth. If the operator doesn’t have time to switch tires, make ruts parallel with the intended direction of travel for the swather and combine so growers can keep up their harvest speed.

If drift risk is keeping you off the field, consider a coarser spray to reduce drift. Click here for Tom Wolf’s tips on how to reduce the drift risk. Click here for photos of drift damage to canola.