Prevent weed patches from setting seed

September 5, 2019 - Issue 23

At harvest, farmers may opt to cut around patches that are heavily infested with weeds. They do this because green weed material can plug the combine or they don’t want that green material in the bin. These cut-arounds are easy to do when straight combining. The key is to destroy those patches with a mower or cultivator before they set seed. Depending on the weed, this may have to be done before crop harvest in order to stop seeds from maturing.

While at those patches, check to see why the weeds are so abundant. Was it a slough that was too wet to seed? Was it a sprayer miss? Are the weeds growing because disease or salinity wiped out the crop? Are the weeds herbicide resistant?

Clues that a patch of weeds are herbicide resistant: One, the patch has no clear boundary. (As Saskatchewan Agriculture weed management specialist Clark Brenzil describes, the patch will have diffuse boundaries that kind of follow machinery pathways, as the patch often spreads by the combine or soil-moving equipment spreading the seeds, but not distinct boundaries that we would see in a spray miss.) Two, the patch will be one species of weed that escaped the spray. Read more.

What species is it? If the patch is kochia, is it Group 9 resistant? In that case, you really want to contain it/destroy it as early as possible. Or is it a Group-9-resistant invader like tall waterhemp or palmer amaranth?

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