What is in this article?:
- Herbicide-resistant weeds continue to bedevil Mid-South.
- Liberty after Liberty a spraying recipe best avoided.
- New research shows importance of time of day when spraying.
A TENNESSEE COTTON field, pictured in early July 2011, is overgrown with resistant pigweeds. Stuck with a bad situation, the producer tilled the field up and replanted.
Steckel provided several herbicide program evaluations.
In the first scenario the producer has planted Roundup Ready 2 soybeans and has ALS-, DNA- and glyphosate-resistant Palmer pigweeds. What program to use?
- Valor XLT.
“It has Valor and Classic in it. The group herbicide sites of action are 2 and 14. However, only one of those is effective on Palmer pigweed.”
- Glyphosate post tank-mixed with Prefix.
“That gives us two effective sites of action: 14 and 15.
“So, for that group, we’ve got four sites of action but only three are effective for Palmer pigweed. And if the pigweed is already up the Dual isn’t going to help you.”
What’s a more robust plan?
- Authority MTZ.
“That has metrabuzin and Authority in it, both with effective sites of action: 5 and 14. That’s for early pre.”
- Prefix and glyphosate.
“Come back with prefix and glyphosate and that will give us six effective sites of action.”
Steckel acknowledged the financial hit producers can take with the herbicides. “I know I’m not the one writing the checks for these plans. I used to farm with my wife, Sandy, and remember writing checks for herbicides back in the early 1990s. It’s easier said than done. But in order to sustainably manage these weeds, particularly pigweed, we must put the investment in these residual herbicides.”
What about Liberty?
“We use a fair amount of Liberty in Tennessee. It’s primarily what we use in cotton and we have about 15 percent of our acres in soybeans.
“A lot of folks want to compare Liberty to glyphosate. The comparison I use is Liberty to the PPO herbicides. Liberty is non-selective, primarily on broadleaves. Liberty won’t give any residual. Some will – like Reflex, Flexstar.
“They work a bit different in the plant but they’re very similar in that they’re contact herbicides. So, you need good coverage. That’s critical.”
And there’s a big difference, said Steckel. “If you spray pigweed that’s too big with Liberty and burn it you can often come back 7 to 10 days later with another shot and control it. That isn’t the case with (the PPOs).
“I hate even mentioning that because from a resistance management standpoint spraying Liberty after Liberty is awful. But it is a fact and in some of these train-wreck fields that’s where we are.”
In a system, Liberty is very robust where it is utilized with a few other herbicide modes of action. “One of my favorites is Prefix pre followed by Liberty. Put a bit of Dual with the Liberty and you’ve got a really good resistance management program.”
- Authority MTZ pre followed by Liberty tank-mixed with Prefix.
“I really like Liberty tank-mixed with Prefix -- three different modes of action. It’s a bit harder on the soybeans. It’ll burn them but it’s very effective in my research.”