Clinton: Good morning and welcome to SunUp. I’m Clinton Griffiths. It’s good to be back along with what appears to be the return of spring. As things green up, weeds are taking off. That’s why SunUp’s Kathy Shelton is here with a look at dealing with those weeds in a no-till operation.
Kathy: Here on SunUp we’ve talked a lot about the benefits of a no-till operation and how to get one started and the equipment you should use. One thing we haven’t touched on just yet is how to control the weeds in those operations. Here to help us out with that today is weed extension specialist Joe Armstrong. Good morning Joe.
Joe: Good morning.
Kathy: Why are weeds such a big concern in no-till?
Joe: In no-till production systems, obviously we’re eliminating our mechanical weed control options, so now we’re relying primarily on chemical weed control and cultural weed control methods. Cultural weed control methods would be things like crop rotation, row spacing, plant population or planting date in some situations.
Kathy: So a lot of these weeds can be controlled with herbicides but how do the growers pick which herbicide to use?
Joe: Certainly crop rotation is the biggest piece of the pie in your no-till production system. You have to choose herbicides that will control weeds that you’re fighting in each particular crop but then avoid any herbicide carry over problems with those herbicides so you don’t have injury in subsequent crops in that rotation.
Kathy: Will a lot of these weeds be resistant to some of those herbicides?
Joe: That’s the big issue that’s coming in in no-till production. Here in Oklahoma we don’t have a lot of these herbicide resistant problems that they have in other parts of the U.S. In the corn belt and in the southeastern part of the United States where they use a lot of glyphosate resistant corn, soybeans and cotton, they’ve relied basically on that one herbicide for many years now. They’ve selected for some of those herbicide resistant weeds. Those can quickly become the biggest problem in a field just because of their aggressive nature. Here in Oklahoma we’re behind a little bit in some of that adoption so we haven’t had those resistance issues just yet. But now we are starting to run into some of these problems.
Kathy: What are some of the weeds that we can expect to see?
Joe: Small seeded weeds are going to be the biggest problem in no-till so things like pigweed species, water hemp, palmeranorans, grass weeds, usually they’re smaller seed as well, can become a bigger problem. Probably the biggest weed problem in no-till production nationwide is mare’s tail or horseweed.
Kathy: You have some of that here with us this morning.
Joe: We’ve collected about twenty samples last fall from around the state in different no-till systems, again soybean, cotton, corn. We’ve been screening those here in the greenhouse for resistance to two different herbicides, glyphosate or Round-Up and then an ALS inhibitor product, called First Rate. Might also use MALS product on wheat called Finesse or Amber some of those products.
Kathy: What do you guys hope to get from this study that you’re doing right here?
Joe: Driving around the state and we’re collecting these samples we found a lot of fields that had mare’s tail scattered throughout. So based on what I’ve seen in other parts of the United States, my first concern was resistance. However, mare’s tail is a tricky weed. Once it gets a little bit of height to it, it’s going to be very difficult to control with any herbicide. Really when they’re this size here is the best time to control them. However, if they are resistant, even if you spray them when they’re in this rosette growth stage here, very small, if they’re resistant you’re not going to control them then either.
Kathy: So that’s when you go back to the important stuff. Crop rotation and what else do you need to focus on besides crop rotation?
Joe: I think crop rotation is probably the biggest thing because that allows you to use different herbicides from different herbicide modes of action. Include a little diversity in that weed control program. There are other things. We talked about narrow row spacing. Many guys that produce soybeans in no-till systems often drill them in seven and a half inch rows or narrow rows. That helps provide an earlier canopy cover which will help reduce the dependency on herbicides, at least later on in the growing season.
Kathy: Is this something that growers need to consider early, stay on top of it? What time of the year should they really be focusing on this weed control?
Joe: In no-till weed control becomes a year round concern. Of course, any crop is important but mare’s tail’s one of those weeds that can germinate almost year round. Ten or eleven months of the year. You don’t want to wait until you’re right up to your planting time in the spring, maybe with soybeans or grain sorghum in a no-till situation. You want to control this in the fall and help knock back some of those populations. Look at early spring applications to help keep mare’s tail in check. Otherwise you’re going to get to planting you’re going to have large plants that will be very tough to control.
Kathy: Something you really just need to stay on top of?
Joe: Yes. Year round.
Kathy: Thank you so much for your time today Joe.
Joe: Thank you Kathy.