What is in this article?:
- Game plan to win against pigweed in Southern soybeans
- Middle Tennessee soybean farmers get Palmer problems
- You want to win against pigweed? The devil's in the details.
- Start clean. Use the right residual and get it activated. Get the post-emergence herbicide application in the field before the biggest pigweed hits 3 inches.
- Palmer problems started building in Middle Tennessee in 2011 and growing, but growers there can learn a lot from West Tennessee growers who have fought pigweed longer.
IT'S TOUGHER done than said, but the concept is easy when it comes to fighting pigweed in soybeans: Start clean and keep it clean and don’t let the weed get higher than three inches. The details make the difference.
It’s a tough fight, but there is no reason for Palmer amaranth to kick a soybean grower’s butt.
Some growers continue to struggle, but soybean farmers now have the tools to win against it. So how can farmers not lose against pigweed? Two Southeast weed specialists have good game plans.
Even though the tail end of harvest for this year is in sight, it’s never too early in Georgia for farmers to get pigweed strategies lined up for next year's row crops, including soybean. Get a good plan and stick to it as best able, said Eric Prostko, weed specialist with the University of Georgia Cooperative Extension.
“As it has been said before ‘the devil is in the details,’” Prostko said. “In my opinion, there are three details that growers must use if they ever expect to get a handle on Palmer amaranth control.”
No. 1: Start clean. You will lose if you plant soybeans into a stand of Palmer amaranth. Till it, burn it down with herbicides or use rye cover crops, but start Palmer–free. If there will be a long delay between tillage and planting, use of a residual herbicide to prevent Palmer emergence during that time period.
No. 2: At least one or even two residual herbicides will be needed for the season. “Sadly, the good old days of just spraying glyphosate or Liberty are over (in Georgia),” he said. “There are many effective residual herbicide choices.”
Authority MTZ, Boundary, Canopy, Dual Magnum, Envive, Tricor, Warrant and Valor all work. “I would prefer herbicides like Reflex or Prefix be applied postemergence. These are the only over-the-top herbicides that will control small emerged Palmer plants and provide residual activity,” Prostko said.
Even if a farmer uses a LibertyLink soybean system, he still needs a residual herbicide. But a residual is only good if it can be activated timely with irrigation or rain. If not activated, the soybean farmer will lose against pigweed.
No. 3: Postemergence herbicide application must be made before the biggest pigweed hits 3 inches. If the plants are bigger, well, you know, a farmer will lose against pigweed. Scout fields once a week or more, he said, and do it from outside of the truck.
“My greatest wish is that I never again receive a phone call about how to control 12-inch Palmer amaranth in soybeans. That is a question for which there is no answer. … Palmer amaranth control does not have to be the major management issue. I will be the first to admit that it is not easy.”