What is in this article?:
• Everyone probably should not be using the same program.
When you look at the yield data, there’s not a statistical difference in yield between the recommend postemergence treatments.
POST-HARVEST CONTROL is an important component of controlling troublesome corn weeds such as glyphosate-resistant Palmer amaranth pigweed and tropical spiderwort.
“When you first get a look at the field, you may have some concerns about the injuries you see on the plants. But when we take those plants to yield, even where we had injury, we really didn’t see any difference in yield, so I’m still very confident that the herbicide treatments we’re using aren’t doing any undue harm.”
Many growers now are making 250-plus bushel corn yields, he says, but researchers haven’t been able to duplicate that in trials for a couple of reasons, including irrigation and rotation issues.
“But we’re getting better. There are a lot of stresses when growing a crop, including heat, insects and diseases. Where you’ve got higher yields and you’re managing all the stresses you can, you start to wonder if herbicides are doing something to affect those yields.
“We’ll continue looking at this in the future, especially in on-farm tests, to make sure we’re not putting any undue stress on the plants with herbicides.”
There are a few new products on the market this year, including Zidua, marketed by BASF, says Prostko.
“It’s an 85 WG formulation with a primary ingredient of pyroxasulfone. We can use it preplant incorporated, pre-emergence or early postemergence. It provides residual control of annual grasses and certain broadleaf weeds, including pigweed.
“It doesn’t bring a new mode-of-action to the table, being the same as Dual or Warrant, but at lower rates. An advantage is that it’s a lower-use-rate material of 1 to 2.75 ounces per acre.”
FMC will be marketing the same ingredient — pyroxasulfone — in two products, Anthem and Anthem ATZ. Anthem is Cadet and Zidua, and Cadet does have postemergence activity, he says. Anthem ATZ contains atrazine.
“Everyone is talking about 2,4-D and dicamba-resistant technology in cotton. The 2,4-D technology also will be available in corn. In fact in 2013, Dow will launch its Enlist herbicide-resistant corn in the Midwest. These are corn hybrids that have enhanced tolerance to 2,4-D.
“We could use 2,4-D in conventional corn, but we were restricted in terms of rates and time of application. This technology allows for higher rates and more flexibility in the timing of applications.
“We can go to a later application date without causing any yield problems. The biggest issue for us will be off-target movement of the herbicides.”
Prostko reminds growers that once they get corn out of the field, their work isn’t done regarding glyphosate-resistant Palmer amaranth pigweed.
“We would like to see you implement a fall program for the management of Palmer amaranth pigweed. This could include several things, including tillage. We need to control the fall population and prevent it from producing seed.”
Researchers have spent a lot of time in the last seven years or so focusing on controlling Palmer amaranth in all crops, he says.