- One of the keys to managing pigweeds is more effective use of residual herbicides.
- Watch the weather patterns and try to get residuals out in front of rains or irrigations.U
- Use some residual herbicide in every soybean field whether they are Roundup Ready, LibertyLink or conventional systems.
Soybean planting is in full swing and some areas of Arkansas have been too wet, some too dry and some just right. As weather patterns push everyone to hurry, I wonder how many will follow through with the good intentions to use a residual herbicide in soybeans.
Then if you use one, it must get activated. In some of the dry areas of the state that may be difficult.
After conversations with growers and weed scientists, I know we have more growers who want to get on top of the pigweed problem — either with prevention or by turning around an existing problem.
Sometimes our best intentions can go by the wayside the closer it gets to the time to do it. I have told my university counterparts that in hindsight perhaps the PigPosium should have been held in March instead of last November. It would seem as if some of the fever pitch enthusiasm that was there last fall has turned to complacency the closer we get to planting.
I will predict that a lot of growers will do a better job and a lot of fields will be cleaner this year. Unfortunately, I also predict that we will have more cotton and soybean fields either abandoned or replanted due to Palmer pigweeds this year than last.
Too many still have not come to grips with what all it is going to take to turn this thing around.
One of the keys to managing pigweeds is more effective use of residual herbicides. Watch the weather patterns and try to get residuals out in front of rains or irrigations. I encourage the use of some residual herbicide in every soybean field whether they are Roundup Ready, LibertyLink or conventional systems.
In the Roundup Ready and conventional fields where you have pigweed problems, you will need to stack residuals in most cases. However that is only the start. Keep in mind the control from a residual may range from 0 to 100 percent control. Also keep in mind the residual may delay emergence of the pigweeds and “buy you some time” or it may not.
The real key to success regardless of the system you are using is the timing of the first postemergence herbicide application. In Roundup Ready or conventional soybeans, the first postemergence application needs to be no later than 10 days after emergence. Some ask, “crop emergence or weed emergence?” They will usually be the same unless you get exceptional control from the residual herbicide.
You may get 90 percent control from the residual but if any pigweeds emerge with the crop, apply the postemergence treatment as close to 10 DAE as possible. Also do not hesitate to stack a residual like Dual or Warrant with the application.
The first application will normally be Flexstar unless Prefix or an equivalent generic was used pre-emergence. By label you only get one full rate of Prefix, Reflex, Flexstar or generic per season.
The best back-up is Ultra Blazer but you need the rate of 1.5 pints per acre.
In LibertyLink soybeans, things just got hotter if you need it. The maximum use rate for soybeans just got increased from 44 to 65 ounces per acre. This means you can use a 36-ounce followed by 29-ounce split application if needed.
One of the reasons I have heard for not planting LibertyLink soybeans is the 22-ounce rates are too low. Two 22s have actually been quite good when properly timed. I must also admit to being a big fan of two 29s — timed like I would the 22s.
The higher use label definitely allows more flexibility and better stewardship of the technology. The higher rates can be more forgiving when normal things delay applications. However, using the higher use rates as a reason to delay application timings can be a huge mistake.
I hear well-meaning folks talk about Ignite on LibertyLink soybeans and Flexstar in Roundup Ready and conventional beans in the same sentence. There is no comparing Flexstar to the firepower you have with Ignite in LibertyLink soybeans. However, timing is still very important.
Use a residual in the LibertyLink system to take the top off the pigweed population and time the first Ignite application at 10 to 14 DAE.
I challenge you to change your mindset in all of the above systems from “how big a weed can I kill” to how early can I get in there to make my first application?”