15 Follow us on @PrairieFarming Better Farming | October 2024 come to mind. These are weeds that emerge in the fall, survive the winter and continue growing in the spring,” says Tidemann. “The problem is that by your pre- seeding burn-off, some of those weeds will be out of the stage of control because they’ve been growing since fall.” These winter annual weeds include cleavers, shepherd’s purse, and stinkweed. Prang adds, “Winter annuals are strong competitors for water and nutrients in the spring. These weeds have a head start. You want to make sure you’re controlling them from the end of harvest to freeze-up, weather dependent.” For perennials, Canada thistle, quackgrass, and perennial sow-thistle are just a few of the weeds that producers should be watching for. Prang says that fall is also an ideal time to control perennial weeds. “If we have a really nice, long fall it will be crucial to manage these weeds. Usually, they are best controlled from mid-September to mid-October and you need the weeds to be growing after harvest to get control,” explains Prang. Tidemann adds that this is because the plant’s energy sink will move as it prepares for winter. “A lot of systemic herbicides will move from source to sink. That means they will move from where they are applied to where the sink is in that part of their cycle. If they are growing it will move to the stem; if they are flowering it will go to the flower,” says Tidemann. “In the fall, most plants start to put their resources to the roots to be able to regrow from the root system the next spring. “So, to get control of the plant and not just the top growth, applying in the fall to get into the root system will be more effective.” During and after harvest is also an ideal time to identify which weed species are present in the fields, as well as any challenges with the current year’s weed control. As producers combine, they have a chance to see the whole field from above. They can evaluate how the crops yielded, and see problem patches and spray escapes as they drive. They can also determine if there are specific species which appear to be escaping control. These would be candidates for herbicide resistance testing. “Scouting is a big part of it. The best way is to have boots on the ground, seeing how many weeds are in the field and what kinds there are,” says Tidemann. “Weeds in environmental stress conditions can change colour. Some of those weeds will go almost purple in colour, so you won’t see the field green up and might not notice the weeds from a drive-by or an image.” Prang also encourages producers to keep their crop rotation in mind and consult their agronomist when selecting control options. Post-Harvest Cleanup ...when flexibility and yield unite ™ ® Trademarks of Corteva Agriscience and its affiliated companies. © 2024 Corteva. Optimum® GLY is the highest yielding glyphosate-tolerant trait on the market, created to unlock agronomic excellence. Pioneer® brand canola hybrids with the Optimum GLY trait allow you to make the herbicide applications you need without impacting the yield potential of the hybrids you love. Learn more at Pioneer.com/ca
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