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A second application of in-crop herbicide is not always economical if the crop is well established, competitive and ahead of the remaining weed population. A second application can make sense if…
In-crop
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Grassy weeds are getting ahead of the canola in some fields. Timely weed control is essential… -
Wait for signs that canola plants have started regrowing before spraying after a frost… -
Weeds will be going strong with the sun, especially if they have established roots that reach moisture while newly seeded crop battles dry topsoil conditions. A second pre-seed burnoff may be in order or — if emergence is likely to be slow — the post-seeding pre-emergence window may be a little wider than usual. Either way, early weed control remains… -
Early weed control with lower efficacy is generally preferable to no control at all or late control with higher efficacy — as long as weeds are present and not frost damaged… -
Early weeds have large impact on canola yield potential. Past research has demonstrated an advantage of 3 bu./ac. for controlling weeds at the 1-2 leaf stage of canola versus the 3-4 leaf stage, and a 7 bu./ac. advantage for the 1-2 leaf stage versus the 6-7 leaf stage. Weed control timing has a huge influence on overall crop profit with… -
The first few weeks of the growing season is a great time to police fields for suspicious weeds. Look for weeds that lived through the pre-seed burnoff or post-emergent sprays while others of the same species have died. These few weeds could be resistant to one or more herbicide groups, and it would be good to nab them early. Diversification… -
While cleavers are a bigger issue in canola, given the competitiveness of the weed and the grade loss from weed seeds in the sample, growers have more options to effectively control cleavers in cereal crops. Effective cleavers management is best done with a whole rotation approach… -
Late weed control significantly increases the yield loss from weed competition, and it can also damage canola plants. However, the yield and economic risks from a later in-crop spray could make sense... —If growers use canola as a clean up crop for Group-1 resistant wild oats, narrow-leaved hawk’s beard, round-leaved mallow and other tough weeds, a second herbicide application may…
