I am going to finish this series on Palmer pigweed control in soybeans with several articles on LibertyLink soybeans.
In this series I have attempted to take a similar approach to the topic that Bob Scott used to show off his pigweed research trials at Newport, Ark., on a field day this summer.
He showed his conventional treatments first and a few of them provided excellent control. I did my best to capture those in the articles on conventional soybeans and at the same time convey some of my experiences on all the ways conventional programs can fail.
Bob next showed his Roundup Ready plots and some of the treatments where conventional herbicides were added to the program and properly activated were very clean. Again I attempted to convey these in the articles on Roundup Ready soybeans and to point out there are some programs in Roundup Ready soybeans that can work.
Next, Bob showed a study where he evaluated a series of salvage type treatments to see if he could find something to control pigweeds after a residual and first postemergence treatment had failed in either conventional or Roundup Ready soybeans. Different treatments made them mad to varying degrees, but in the end they all failed.
That, too, was my experience back in the “good old days” and I attempted to convey that in the previous articles.
The final series of studies Bob showed on the field days were the LibertyLink trials. In those, almost every treatment that included Ignite provided excellent pigweed control. Those treatments included different combinations of soil residual herbicides followed by Ignite and also two applications of Ignite applied alone.
The only treatments that had any pigweeds in them were some of the single applications of Ignite with no residual treatment or some of the treatments where he deliberately allowed the pigweeds to get too large before the Ignite application.
Of the herbicides currently available for resistant pigweed control in soybeans, Ignite has by far the best postemergence activity. For that reason I believe LibertyLink soybeans provide the best chances of consistently controlling Palmer pigweed.
The fact that most of the LibertyLink treatments provided excellent control in Bob’s plots means that system should perform more consistently over a range of situations and environmental conditions.
The fact that LibertyLink soybeans and Ignite herbicide allow the best options for pigweed control does not mean things will be quite as simple as spraying glyphosate on a susceptible pigweed. LibertyLink is excellent technology but one you will have to learn how to use.
When Dick Oliver and I were looking at both Roundup Ready and LibertyLink soybeans in the development stages in the mid 1990s, it was obvious that both Ignite and Roundup were very broad spectrum over-the-top herbicides and both had excellent crop tolerance — if you sprayed the Roundup on the Roundup Ready soybeans and the Ignite on the LibertyLink soybeans!
When comparing the two, the general observation was Roundup was better than Ignite on pigweeds and grasses and Ignite was better than Roundup on weeds such as morningglories, smartweed, coffeebean, gourds and some others.
In some ways I wish LibertyLink soybeans were being introduced on weeds like the morningglories because it would be hard to mess it up. In reality, however, essentially 100 percent of the LibertyLink soybeans are going to be planted in fields where Palmer pigweed is the number one problem. Most all of these fields also have a grass problem. These are two weeds are not necessarily the strong suit of Ignite herbicide.
However, through the right programs and proper use it can be made to provide excellent control of these weeds — just as we learned how to make glyphosate and Roundup Ready programs perform well on weeds that were not the strong suit of that system.
The key will be learning to use Ignite like Ignite and not glyphosate.
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