Subscribe
Share
Share
Embed
The NDSU Extension weekly podcast In the Pod: Soybean Updates delivers timely insights and expert advice on soybean production.
You're listening to In The Pod, soybean updates, a weekly trek into the latest soybean information from NDSU Extension. Should soybean farmers put much effort into weed control in the fall? According to Joe Ikley, NDSU Extension weed control specialist, soybean weed management for next season starts now. Joe, let's talk about fall applications. What needs to be done?
Joe Ikley:We often look at fall as a great time of year to work on weed control, whether that's working on perennial weeds to set us up for future success or trying to control winter annual weeds now before they become more difficult to control in the spring. Or the past several years, a lot of our focus has been which herbicides can we put out fall to help us control our spring and summer annual weeds that will emerge next year. So, really, no matter what kind of weed you're looking at, we have these different programs we've been evaluating to help us, again, get better success for next year because oftentimes, we'll park stuff for the winter, bring them back out during planting, tight planting window hits, and weed control might take a back burner. So oftentimes, our falls have been a little bit more dry, more time to work at least in the field and trying to take advantage of those opportunities for weed control.
Bruce Sundeen:How important is the burndown application?
Joe Ikley:Burndown, this is a very important time of year for us. A lot of our perennials, this is the time of year where they are taking their carbohydrate reserves and putting them into their overwintering structures often below ground. Think of the extensive rhizome of a Canada thistle plant. It's taking all the carbohydrates from that green tissue, sending it down to those rhizomes. And if we can have a herbicide go along for the ride, that gives us better overall control because we're getting herbicide into those overwintering structures, again, to kind of help with overall better control. With our winter annual weeds, those are often germinated by now. And if we spray them sometime in October, we get a good kill, an easier kill of those weeds with relatively cheap programs now compared to when they overwinter come next spring. They've survived the winter. They're a lot more hardy, more difficult to control as we have cooler temperatures in the spring. If we take a cheap program now, it's gonna be more effective on those winter annuals in the fall compared to taking that same program and trying to control those same weeds next spring.
Bruce Sundeen:Do the drought conditions affect applications?
Joe Ikley:So oftentimes, these perennial weeds will be more drought tolerant than the grass we have them growing in. As long as they're still green and have some active growth, they will still absorb herbicide and we could still get some level of control. Oftentimes in these drought conditions, these very dry years, is that compare that to an area where you don't spray, then come back next spring, next summer. Where we sprayed, we can contain that population. The areas we don't spray, they continue to proliferate, and the footprint of that perennial weed will spread. The short answer is we still wanna spray those perennials in these dry conditions because we still see a benefit. When we think about the winter annual weeds, all it takes really is a rainfall event or two to get those things going. They're all often very small seeded weeds, so they're gonna germinate in that top into the soil profile. So even if we're lacking subsoil moisture, if we get rainfall event to hydrate that top of the soil, they will germinate, and they will continue to grow. We can still apply to those winter annuals and get good control.
Bruce Sundeen:Joe, what about applications for next spring? What are some of the guidelines?
Joe Ikley:We've been really evaluating some of our water insoluble herbicides, making applications in the fall to then gather the moisture through snowfall, snow melt, and some rainfall to get that into the soil profile for our summer annual weeds next spring. So historically, we've talked about things like kochia. Using flumioxazin, main trade name of Valor. Historically, we've used that in the fall for kochia control next spring. We have some resistance to that, so we're looking at some different options, but we've had a lot of focus on pyroxasulfone. Main trade name there is Didua. But we've been applying that as late as we can to ground freeze up so that we minimize the amount of degradation of that herbicide in the fall and have most of that product still available there in the spring. So we've seen benefits for that on not only kochia, but for wild oat control as well. With those two weeds specifically, much better control from a fall application compared to a spring application. What benefit will we get from pyroxasole foam applied in the fall on waterhemp? So this past year, we had some different trials applying higher rates of pyroxasulfone in the fall. And where we did not get much moisture all year, we actually were able to get close to season long control of waterhemp if we had the rate high enough. So that's gonna be a continuing avenue of research moving forward. Very promising results, but I'm gonna put an asterisk on that every time I talk about it all winter because of the dry conditions we experienced throughout this growing season.
Bruce Sundeen:Thanks, Joe. Our guest has been Joe Ikley, NDSU Extension weed control specialist. You're listening to In The Pod, Soybean Updates, a weekly trek into the latest soybean information from NDSU Extension supported by the North Dakota Soybean Council.