Fall Burndown: Gaining Ground In The South

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Fall burndown applications haven’t ranked as high on the priority list in the South as in parts of the Midwest. But to a degree, farmers in the Cotton Belt are taking the practice more to heart, working it into their plans – and their budgets.

That may be especially true in flatter areas in the Delta states where thick winter cover isn’t a critical point in terms of soil conservation or in meeting requirements in conservation plans.

As an example, many Arkansas farmers have adopted a new rule of thumb for their weed control programs – never walk away from emerged glyphosate-resistant Palmer amaranth, regardless of the time of year. In other words, eliminate pigweed when you see it, even if that means extending weed control into the fall.

“In our early corn and some of our early soybeans, we have a long enough growing season that glyphosate-resistant Palmer amaranth can grow and actually produce more seed after harvest,” says Bob Scott, University of Arkansas Extension weed scientist. “As a result, fall burndowns have become a lot more common in this state.”

Producers who’ve worked diligently to knock back Palmer during the season don’t want to lose those gains to a fall flush – particularly with a weed like that can quickly shift its focus to producing a seed head when it senses that days have grown shorter. As weeds go, it’s a tricky one.

Italian ryegrass – earlier is better, too

Fall burndown applications also can target other resistant weeds in the Midsouth, including Italian ryegrass, Scott adds. “If you can control that fall flush of ryegrass, you’ll eliminate a good portion of the ryegrass population. That applies whether you’re going into a row crop the following year or you’re fallowing some ground – or if circumstances prevent you from planting wheat.”

In Belzoni, Mississippi, Trey Koger has adopted a fall approach to managing glyphosate-resistant Italian ryegrass.

“On my light ground that’s going to be in corn the following year, I put out a fall herbicide,” says Koger, who grows corn, cotton, soybeans, rice and peanuts. “That way, we can drop in and plant clean in corn. Hands down, a fall program is the best way to manage glyphosate-resistant ryegrass.”

Corn provides a fit for fall burndown

In Mer Rouge, Louisiana, producer Matthew Turner jumps on weeds emerging in September and October. He aims to catch them while they’re small and easy to knock out.

“We go behind corn harvest with Select, 2,4-D and glyphosate,” Turner said. “The Select is for the Italian ryegrass and volunteer corn, the glyphosate covers other grasses and the 2,4-D is strictly for Palmer amaranth. We’re trying to get the Palmer before the seeds get washed all over creation before winter starts.”

One drawback to fall burndowns is that it’s a difficult time of the year for farmers to muster up any enthusiasm for further field activity. Part of that has to do with logistics but sometimes it gets back to exhaustion or lack of budget, Scott notes.

“A lot of producers are harvesting right up until frost, so it’s tough to add late spraying to the workload,” Scott says. “Frankly, farmers in the South like to hunt, enjoy the outdoors and are simply looking forward to some time off.”

That fall burndown also costs money at a point when farmers are paying off bank notes or have run out of money for the current year’s crop, Scott points out.

“I always look at it as an investment in next year’s crop, but some farmers don’t have any budget left for weed control by then,” he says.

Chemical approaches

Many Arkansas producers will apply paraquat for their fall burndowns, according to Scott.

“If they’re trying to pick up volunteer soybeans or corn, they may add glyphosate or glufosinate. Some producers may use 2,4-D, but remember there is a cutoff date for the product.”

Scott also suggests adding a residual to the tank mix, noting fall labels for Dual in certain geographies.

Many fall burndowns have post-harvest timings, with the window in Arkansas ranging from the end of August to the first part of November, Scott emphasizes.

Midwest perspective: time to jump on horseweed

In Illinois, fall burndowns are directed at henbit, chickweed, dandelion and glyphosate-resistant horseweed.

 “The applications are done primarily by no-till farmers who can’t always get their spring burndowns put on in a timely manner,” said Bill Johnson, a weed scientist at Purdue University. “If we have a warm, wet spring and are not able to get across the field, we can have grown up wooly messes.

“We are strongly recommending that they use a fall-applied program to manage fall-germinating horseweed. They may have some germinating in the spring, as well, but those aren’t nearly as hard to control as the fall germinators.”

Dicamba and 2,4-D are the two most widely used products, according to Johnson. “If producers have an early harvest and they need some residual in the fall, we’ll recommend metribuzin if they want flexibility to go to corn or soybeans. We recommend simazine if they are going to corn.”

Midwest producers don’t have as much of a problem with horseweed going into corn because they use more tillage and have more broadleaf herbicide options for corn. “Producers have tried Princep (simazine) and 2,4-D or dicamba mixtures. If there are any grasses coming up in the fall, we ask them to add some glyphosate,” Johnson said.

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