Any cotton grower who has fought the good fight against Palmer amaranth has a pretty good idea what his defense budget looks like. But to put the full impact of pigweed infestation into perspective, it helps to take a 10,000 foot view of the situation.
Stanley Culpepper has. And the numbers are astounding, but not pretty.
“Most growers are spending between $75 and $100 per acre annually on Palmer amaranth control,” said Culpepper, University of Georgia Extension weed specialist, speaking at a Raising More Profit event in Tifton, GA. “But collectively, growers in the cotton industry have now invested over $1 billion to control this one plant in one crop in one decade.”
Culpepper is quick to praise growers for their positive response to the pigweed plague, recognizing that many of them have adopted aggressive management programs to help clean up their fields. He also recognizes that those programs are costly. And in times when cotton prices are down, it can take a big bite from the bottom line.
“If we’re going to improve profitability in weed control, it has to come by reducing herbicide expenses and removing or reducing hand weeding,” he stated. “Of course, we have to get better weed control while we do it. That’s still our overall objective.”
He emphasizes two key components for profitable management – start with a clean field at planting and work to maximize in-season weed control.
“If you’re planting and pigweed is already up on 20 percent of your fields, you need to go out the day before planting and clean it up,” he said. “I know growers think that costs them money. But it actually saves a tremendous amount of money, especially when it comes to hand weeding.”
For in-season control, Culpepper stresses that growers need to look at program recommendations and figure out how to best make them work in their fields. They need to understand the aggressive growth patterns of Palmer amaranth. And they need to maximize the activity of each herbicide they use.
Timing, of course, is all-important. Since most pigweed historically emerges 18 to 21 days after planting – even in clean fields – the first three weeks of the crop needs the most attention.
“This is where I believe growers can save the most money, reduce herbicides and reduce hand weeding,” stated Culpepper. “One of our programs has the first post application 13 to 16 days after the pre-emergence application on a Roundup system. If growers are using a Liberty system, they may gain one or two days of flexibility, but not one or two weeks.
“If growers want to reduce hand weeding, they need to start clean and focus on that good pre application, followed by that first post application timed closer to planting.”
Culpepper also pointed out that desperate times usually mean more “alternatives” for growers to consider for pigweed control. He urged growers to be wary, especially if they’re looking to save money.
“People are desperately looking for alternatives to help with pigweed,” he said. “If you want to make money, you don’t go out and do the research for these companies. That does not increase your profit. Make sure the products have been tested. Ask for the data. If they’re a reputable company, they’ll have reputable data.”
Aggressive weeds call for smart, aggressive weed control programs. The concept of spreading out herbicide applications – which worked well in a Roundup Ready system – is now, in a word, a disaster, says Culpepper.
“Keep the focus on the first three weeks after planting for best control of pigweed,” he stated. “By spreading applications, it means more spraying to try to recover. And that also means more hand weeding.
“When you try to play catch up, you don’t catch up.”