Timely Defoliation Has Its Advantages
August 28, 2026 Every production season offers a little different scenario than the one before. And on the topic of harvest preparation and timing, those little variables can cause great consternation for cotton producers.
Just this year in the Mid-South, producers took advantage of an unusually warm and dry early spring window to plant – before a period of heavy rainfall set in. The net result is that a portion of the cotton planted in Mississippi in 2026 is several weeks behind the majority of the crop.
“That’s two totally different crops,” says Brian Pieralisi, Extension cotton specialist with Mississippi State University.
While the crop in Mississippi appears to be in great shape, according to Pieralisi, that gap in crop maturity from one field to the next could be cause for more complexity when it comes time to defoliate.
“I always say the most complicated part of this whole cotton management and production practice is when you get to the defoliation, and you’re trying to do a good job,” says Pieralisi. “There’s a lot going on there. It’s not all straightforward.”
One wildcard, he says, is overnight temperatures during defoliation. That will determine whether producers should use a hormonal mode of action or a herbicidal mode of action to optimize defoliation efficacy.
“When it’s cooler than 60 degrees, you’ve got to use herbicidal chemistries for the defoliation process to begin,” Pieralisi says. “When it’s greater than 60 degrees, you can use hormonal products. That’s what you want, it works a lot better and it’s gentler. These hormonal products are going to create the abscission layer a whole lot cleaner.”
Pieralisi notes that the herbicidal products initiate damage to a leaf — which has the potential to hinder the plant’s ability to create an abscission layer, which is what prompts the leaf to fall cleanly off the plant.
Things get much easier for producers when application temperatures remain above 60 degrees, allowing them to use a hormonal product such as thidiazuron to knock the leaves off the plant. Growers can also use a product like ethephon to help open the bolls. Folex is also a popular go-to for producers who are able to defoliate in warmer weather.
Late-season rains, which are common in the Mid-South, can throw an added wrinkle into defoliation planning. Most of his producers, Pieralisi says, plan on a two-pass program out of necessity — after a rain delays or otherwise hinders an initial application.
Ultimately, producers should plan to begin harvesting roughly 10 to 14 days after the first defoliant application.
Delayed Decisions in the Southeast
Similar to their peers in the Mid-South, producers in the upper Southeast will have some cotton that is running behind schedule this fall.
North Carolina had a long dry spell early in the production season that set this cotton crop behind schedule right out of the gate. Because the state’s crop is almost entirely in dryland production, producers there need a little help from Mother Nature to get the cotton up and moving.
“If I had to predict, I’d guess we’re going to be a little bit late,” said Dr. Keith Edmisten, Extension cotton specialist with North Carolina State University, back in July.
Typically, Edmisten says, his growers are defoliating in early October, and they will begin harvesting later that month, with harvest activity wrapping up in November. But in a year when the cotton crop is running behind schedule, producers may be tempted to give it extra time on the back end to more fully mature. That strategy, Edmisten says, may not always pay off.
A graduate student at North Carolina State University took aim at the topic of delayed defoliation and tried to determine whether waiting later would pay dividends for cotton producers.
Edmisten says his student compared two sets of data — one collected from cotton that had been defoliated on October 15, and another from cotton that had been defoliated on November 1.
“What we found was that we got higher yields when we defoliated in the middle of October, rather than delaying defoliation,” he says. “When we wait until November, we’re usually out of the temperatures that are conducive for opening bolls. So, we lose that ability to open some of those bolls.
“There certainly are exceptions, but for the most part you need to find a good window in the middle of October and go ahead and defoliate your cotton, because we’re not really gaining anything by waiting until November. You get to the point where you’re losing more than you’re gaining.”
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