Palmer pigweed: residual herbicides
Nov 3, 2009 10:31 AM, By Ford L. Baldwin, Practical Weed Consultants, LLC.
Whether you choose conventional, Roundup Ready or LibertyLink soybeans, I recommend a residual herbicide program to control glyphosate-resistant Palmer pigweed.
In last week’s article I wrote that planting LibertyLink soybeans and using Ignite herbicide provide the best opportunity to consistently control glyphosate-resistance Palmer pigweed.
Ignite has the best postemergence activity of the available herbicides and, therefore, provides the best backup for a residual herbicide program.
Whether you choose conventional, Roundup Ready or LibertyLink soybeans, I recommend a residual herbicide program. Perhaps it does not need to be as aggressive in LibertyLink soybeans, but some use of residuals is recommended.
With any of these programs you have to be prepared to deal with the weeds that escape the residual treatments. We have a lot more years in Arkansas where timely rains for activation do not occur than we have wet years like 2009. You must be prepared to deal with anything from a total failure of the residual to anything less than 100 percent control (and you will get very few 100s).
In a conventional weed control program or a Roundup Ready program depending upon conventional herbicides to control the resistant weeds, Flexstar and Blazer are the two primary postemergence options. With either, they must be applied to very small weeds and there is a point at around 14 days after emergence they simply will not work anymore.
In addition, even when they work well it is easy to get 80 percent control with them but very difficult to get 100 percent control.
One of the things we have going for us right now is the resistant populations in a lot of fields are at a low enough level that 80 percent control of any escapes following a residual treatment looks pretty good.
