Whether you have observed it on your farm or not, we are seeing an increase in herbicide resistance across the globe and in Canada. What I see as most concerning is the increasing resistance to Group 9 chemistry, more commonly known as glyphosate products. But there are practices we can incorporate that can prevent resistance.
Glyphosate resistance is happening for the following reasons:
- Limited or lack of crop rotation
- Reduced or zero tillage operations
- Continued use of glyphosate alone
- Multiple applications in same season
- Reduced rates of glyphosate
Glyphosate has been has been a great tool in crop production since 1976, and we need to preserve its effectiveness. Today in Canada there are more than 78 million acres treated with 14-plus brands of glyphosate. Thankfully, a cereal crop is a great crop in your rotation to manage your group 9 herbicide resistance whereas in other crops the options are very limited.
How to preserve its effectiveness? Explore the use of tank mix partners from different herbicide groups when applying pre-seed in cereal crops.
Benefits of a pre-seed burn-off
- Reduces weed competition at an early stage when the crop is most vulnerable to weed competition.
- Provides more options to control hard-to-kill weeds, such as perennials.
- Can potentially reduce more costly in-crop herbicides.
- Avoids the panic around getting in-crop spraying done if weather conditions prevent application.
Benefits of a pre-seed add-in
- Resistance management, particularly against Group 9-resistant kochia.
- Improved efficacy of hard-to-control weeds such as wild buckwheat, cleavers and narrow-leaved hawksbeard.
- Residual activity. Some products have up to 30 days’ activity that glyphosate does not. Glyphosate alone would not control a number of spring annuals that germinate later.
- Control of glyphosate-tolerant volunteer canola cannot be achieved by glyphosate alone.
Glyphosate selection pressure is greatest at low in-crop rates for many of the main weed species, so full rate of pre-seed glyphosate with an add-in is much more effective.
There are so many options now that can be mixed with any glyphosate to help with spring weed control. These now include:
PrePass™ Flex – Group 2
Express® Pro and Express® SG – Group 2
Express® FX – Group 2 and 4
Paradigm™ – Group 2 and 4
Blackhawk® – Group 4 and 14
Goldwing® – Group 4 and 14
Focus® SE – Group 14 and 15
I recommend products that target specific problem weeds. For example, if volunteer canola is expected to be a problem, I would recommend going with PrePass Flex. If chickweed or dandelions are an issue, use a product such as Paradigm, which is now registered for pre-seed use as well as in-crop. The products from NuFarm, such as Blackhawk and Goldwing are great options to switch groups if you’re having problems with Group 2 broadleaved weed resistance.
Always read and follow herbicide label directions. PrePass™ Flex and Paradigm™ are trademarks of Production Agriscience Canada Company, Dow AgroSciences and Pioneer affiliated companies or their respective owners. Express® Pro, Express® SG, Focus® SE and Express® FX are registered trademarks of FMC of Canada. Blackhawk®, Goldwing® and Fierce® are registered trademarks of Nufarm Ltd.