Use an integrated approach to managing Palmer amaranth and aim to start clean.
by Amanda Huber
Remember watching scary movies as a kid, and whenever the main character clobbered the monster and got the better of it, what happened? They always turned to run away. What did the monster do? It got right back up to terrorize some more. It probably set in your mind that if you ever find yourself knocking down a zombie or alien being, just stand there and keep beating it until you are sure it will not get up again.
Now, consider that Palmer amaranth is that monster. Producers have knocked it down using an integrated approach, but now is not the time to let up or this monster will come back with a vengeance.
Use All Available Methods
Eric Prostko, University of Georgia Extension weed specialist, says that, in general, producers have made significant improvements in Palmer amaranth control over the last few years. But he reminds producers that it takes using every available method to manage it.
“Do not rely on herbicides alone. Use other available tactics when you can, such as tillage, cover crops, planting in twin rows and hand weeding,” he says. “Hand weeding, especially, provides valuable benefits in reducing the weed seed bank.”
Remember Resistance Management
Prostko says that herbicide programs that include residuals such as Valor and/or Dual Magnum and timely postemergence applications of Gramoxone plus Storm, Cadre, Cobra and/or Ultra Blazer have provided the most consistent control of Palmer amaranth.
“Those fortunate enough to have irrigation can make their residual herbicides work much better.”
However, herbicide-resistant Palmer amaranth has forced many producers to rely more heavily on certain herbicides such as Dual Magnum and Warrant.
“Additionally, a new herbicide, sold under the trade name of Zidua, is now labeled for use in field corn and will eventually be labeled for use in soybean.
Unfortunately, all of these herbicides have the same mode of action,” Prostko warns. Producers must know the herbicide modes of action being used in all crops on the farm and rotate modes of action as much as possible.
Aim To Start Clean
The final point to remember just before planting is that it is very important to start clean.
“Usually, most problems with Palmer amaranth in a field can be traced back to what was done at planting,” Prostko says. “Do whatever you can at planting with herbicides, tillage and all of your tools, to start clean.”
For Palmer amaranth, use:
• Cover Crops
• Twin-row planting
• Residual herbicides
• Irrigation for herbicide activitation
• Hand weeding