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Weeds determine herbicide timing

I will summarize my thoughts on LibertyLink soybeans and get off pigweeds for a while. I can not promise you for how long that will be because pigweed resistance is a huge issue.

Of the alternatives to a Roundup Ready program, the LibertyLink program is the one most similar. To make it work, use a residual herbicide to get the program off on the right foot. Then, time the first application of Ignite at around 10 days after emergence or to pigweeds 3 inches tall or less. I have provided my thoughts on timing in several articles.

I recently had a discussion with Mike Owen, weed scientist at Iowa State University, in regards to herbicide resistance and Ignite performance in the Midwest. He commented that Ignite had performed well there if applied at an early timing.

He went on to say that people miss the point on timing when comparing herbicides. He said timing should be determined by the weeds and when they become competitive — not by the herbicide — and I agree.

Make the first application at 10 days after emergence. If a new flush of weeds occurs, repeat the treatment when they are at the same stage.

The total in-crop Ignite use rate is 44 ounces per acre per season. Therefore, if two applications will be needed, the rate is 22 ounces per application.

If you miss the timing of the first application, there is a one-shot use rate of 36 ounces. This is one thing that separates the LibertyLink program from one using conventional herbicides like Flexstar. Even the 22-ounce rate of Ignite is more active over a broader spectrum of weeds, but the 36-ounce rate allows you to drop the big hammer if needed.

The company is working to get the label changed to allow two 29-ounce rates. For this reason I often hear the 22-ounce rate is inadequate.

While I like the flexibility and forgiveness of the 29-ounce rates, university research and field experience have both shown the 22-ounce rates will work fine when properly used.

I get a lot of questions about spray coverage with Ignite, and there is a lot of misinformation surrounding this issue. I have heard some say, “Man, I heard you had to use 40 gallons of water to make it work!” The Ignite label says to use 15 GPA with a medium spray droplet.

Most are used to spraying lower volumes with larger droplets with glyphosate. If there is a spray coverage issue in the field, it should be a non-issue. There is a label in Arkansas that allows Ignite to be sprayed at 10 GPA. I know other growers who have preferred higher volumes.

The key is getting a medium rather than course droplet. Often all that is needed with the current glyphosate set up is increasing the pressure. If not, it may mean going down a size or two on tip size.

Air induction nozzles still work fine with Ignite — just use one small enough to provide a medium (300 micron or so) droplet.

I have seen Ignite put out a lot of different ways in the field with success. Remember it is much easier to cover small weeds early in the season than may be the case with a burn down application.

If the set-up you are using is not providing adequate coverage, you will know it and make the necessary changes.

I hear some say if I intercrop LibertyLink and Roundup Ready soybeans, “drift will be an issue” or “I will get in the wrong field spraying.” Whether or not you choose a LibertyLink program, weed control will no longer be as simple as spraying one or two applications of glyphosate across the entire farm. However, LibertyLink soybeans are reasonably tolerant to glyphosate and vise versa.

While anything can be messed up, the drift issue is plenty manageable. Ignite drift is actually much safer to rice than glyphosate drift. I have total confidence that the farmers that have survived this far can keep the fields straight.

If you do happen to get in the wrong field once, you will certainly keep them straight from now on. I have been there, done that.

The weeds will demand that the LibertyLink technology goes forward and is successful. It is equal technology to Roundup Ready, and I believe it holds the key to managing glyphosate resistance for the foreseeable future.

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TAGS: Management
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