When fields are too wet for the sprayer, canola growers do have options for aerial application.
—Roundup WeatherMax is the only glyphosate registered for aerial application at this crop stage. All conditions are outlined in detail on the label.
—Liberty (glufosinate) is registered for aerial application at this stage. Remember, Liberty works best at higher water rates.
—None of the Clearfield herbicide partner products is registered for aerial application on Clearfield canola.
—Poast and Assure II have aerial labels.
In summary, the benefits of aerial are: In many regions, weeds are ahead of the crop. If that’s the case and fields are too wet for the sprayer, then aerial spraying may pay off. Weeds up and growing before the crop have a significant impact on crop yield. (See the table at the bottom of this article on canola losses due to wild oat, taken from page 31 of the Saskatchewan Guide to Crop Protection.) Aerial spraying also avoids wear and tear on sprayers and on the field when conditions are wet. Ground sprayers can leave deeps ruts to contend with in subsequent spray applications and at harvest. Crop once growing in those rutted areas is now gone. And getting a sprayer unstuck can be a long, messy job.
In summary, the downsides to aerial are: You need to leave buffer zones. For Roundup WeatherMax, for example, the buffer zones for aerial application in Roundup Ready canola are 40 metres for shelterbelts and other fields and 5 metres for aquatic habitat. Aerial application also represents another cost for a crop that does not have the profit potential it had before the delays and the moisture stress. On that note, in very wet conditions, growers should make sure the crop has recovered before stacking on the extra expense of aerial weed control. “If that field’s going to be dead a week from now, how much do you really want to invest in it?” says CCC senior agronomy specialistDerwyn Hammond.