Be proactive, not reactive. That’s the key to weed management in soybeans. Even when planted into ideal conditions, soybeans are generally slower to establish as compared to some other crops. They are also extremely sensitive to any competition for sunlight, moisture and nutrients, so keeping weeds out of their way from the start is crucial to achieving your 60-bushel target.
Top-up timing is critical
Many growers ask me about the best time to apply herbicide – my answer is ‘early is best.’ It’s easy to spot fields where weeds haven't been managed properly right from the start. Some growers rely too much on glyphosate; they delay applications believing that a heavier rate will fix the problem. But this reactive mindset almost never works out.
A residual herbicide used as a “top-up” within your glyphosate application is extremely important for effective control. Any time a residual product is used up front, it will help to suppress or control yield-robbing weeds like volunteer canola, buckwheat and kochia, and allow us to get the crop off to the right start.
Ideally, a top-up should be added to a herbicide pass at the unifoliate plant stage. You will miss the boat if you wait until the second or third trifoliate – and the yield impact can be huge. When it comes to volunteer canola in soybeans, yield reduction begins when there are more than two ‘weeds’ per square metre. The amount of yield loss depends on many factors including row spacing, soybean plant population and the number of volunteer canola plants present.
For example, fields planted with a very narrow row spacing and an extremely high plant population will be more competitive against weeds due to a quickly closing canopy. But for fields planted in wider rows, residual top-ups are extremely important to help manage weeds until the canopy closes in.
Do your herbicide homework
There’s no doubt that there are many product options to manage weeds, but it’s critical to do your homework first. Carefully review the label to understand what weeds are controlled, what type of residual activity it provides, and what your re-cropping restrictions are. Consult your local agronomist or rep for advice on what products would be most effective to tackle the weeds in your field. It's also important to look at what other herbicides you've used on the field in the past (and what you plan to use in the future) to ensure you're rotating properly to manage resistance.
An up-front investment pays off at the elevator
Strong weed control in soybeans affects everything from getting the crop off to a good start right up until you haul it to the elevator. Over the last couple of years, I've heard more and more people getting higher dockage in their soybeans. The vast majority are being docked due to canola seed getting into the combine at harvest. Elevators are more sensitive to this issue than they have been in the past and are watching it pretty closely. When you're penciling out your crop protection costs per acre, you’ve got to consider this as well. A residual top-up may seem an unnecessary added cost, but consider that you could be hit in the wallet for dockage.
Whether it’s higher yields or cleaner samples, you will get paid for doing your weed control homework.