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Farming cotton with resistant weeds

Brent and Larry Henderson have a touch over 5,000 row-crop acres, and they're worried for all of it. It hasn't been from lack of trying, but early weed control has been a puzzle the father and son team hasn't quite solved. And the planting season clock is ticking away.

The Hendersons work land in east Arkansas, south of Trumann and just east of Judd Hill Plantation, but their concerns are not isolated. For much of the Mid-South, this spring has reinforced the fact that dry, warm weather and burndown applications — the effective kind, anyway — don't mix. Add in massive Roundup Ready crop acreage, glyphosate-resistant marestail, and the new threat of glyphosate-tolerant pigweeds, and the resulting fears are understandable. Weed scientists and company reps say recent calls about weed escapes have been plentiful.

“We found resistant horseweed on our place about two years ago,” says Brent, the son, sitting at the farm headquarters. “We weren't looking for it. We had horseweed, but it was controllable with (glyphosate). Then, we hit some (resistant) patches about the size of this room. It's bad, now.”

About 500 of the Hendersons' acres are in milo. The rest is in cotton. Some 40 to 45 percent of the cotton is skip-row with the rest in 38-inch rows.

Until this year all the skip-row cotton had been dryland. But on the heels of a drought-plagued 2005, the Hendersons decided to irrigate some of it.

“We began the skip-row about five years ago because of irrigation costs,” says Larry, the father. “With this system, we're saving about a third on fertilizer and a third on the seed and still getting close to irrigated yields. So we're expanding the skip-row this year by about 600 acres.

“We'll also have a pivot field and furrow-irrigated field in skip-row. We're just trying to cut costs and reduce the intensity of the management. It's working for us. I think we're the only ones doing it around here, although some (operations) in Mississippi have used it for a while.”

The cotton/milo rotation is a good one, says Clay Despain, the Hendersons' crop consultant. “From what I can tell, it pays off. It puts a lot back into the soil and helps on a lot of the ground around here.”

Resistant marestail doesn't like competition. “So where you have planted milo you normally don't have a marestail problem the following year,” says Brent. “The (marestail) doesn't go to seed and it aren't as big a problem. It's just helps clean up.”

Last year was dry, as was this winter. Until the last week of April, “we were beginning to worry because all of our no-till ground — and some we'd worked up — was too dry to get a stand on,” says Larry. “We actually fired up three pivots and were about to water some ground to get it ready to plant. Then, it rained.

“I don't like to water cotton after it comes up. Cold water and compaction of the dirt (is a deterrent). But we were going to water the fields as insurance so we'd have a place to begin planting if it stayed dry. Normally, in April, we don't worry about that. But we're in good shape now. The temperatures just need to warm up.”

Spray program

Before the resistant marestail found a home on Henderson property, “we were just going around with a (glyphosate) burndown,” says Brent. “That was working fine. Then, resistant marestail came along and we started putting Clarity in the mix. That worked fine, too. This year, on our no-till, we went with Clarity, Roundup and Valor.”

Using this approach, the Hendersons are trying to eliminate an over-the-top application and get further into the season before having to do anything more.

“We've done a good job on all the other winter weeds,” says Despain. “But we're having a tough time with marestail. You won't have any problem driving this (area) and seeing that weed. Some are dead, some look like they're going to die, and some will make it. There's no telling how many acres I've walked and how much marestail I've cut. I've sought the advice of several experts, but we still aren't sure if the dry spell, the mild winter, or a combination of both, was the culprit.

“We've done a good job with burndown this spring. (Even so), there is still (marestail out there)…If we hadn't put out the Clarity/Roundup/Valor, it'd be really bad.”

The Hendersons have seen burndown failures using Clarity. While over the last few years it's controlled marestail, “this time, it didn't,” says Brent. “We're going to have to go back at planting, or right after, and put out Ignite or something else. That will cost us more money.”

New land

Due to boll weevils, some land the Hendersons recently picked up hadn't been in cotton for 30 years. But after successful eradication efforts, cotton is again on the agenda.

“There's no marestail there, I suppose because of the wheat/drilled beans cropping they've been doing,” says Larry. “We worked up that land, and I believe we'll be able to go in there and plant. Cropping history makes a difference. The same thing can be seen in milo fields. You can go in fields that were in milo last year, and you'll have some trouble finding marestail.”

Last year was the first time the Hendersons have been “really scared” with marestail, says Larry. “Brent…wanted to spray Ignite to get rid of them (around planting). I kind of pooh-poohed the concerns. Later on, they grew up and we put Ignite under the hood to clean the middles. Those marestails in the rows were there all year, and I'm sure they hurt our yields.”

Roundup will knock marestail back and stunt them, says Brent. “It's kind of like giving them the flu. But then they'll flourish.”

“We're scared to death of them now,” says Larry. “We won't put cotton out if there's any marestail surviving. We're going to do our best to make sure they're dead, keep a residual out.”

What are the Hendersons hearing from neighbors dealing with marestail?

“Some are using Gramoxone,” says Brent. “But marestail has to be small for Gramoxone to kill them. And Ignite is very temperamental when it comes to temperature. You need at least 85-degree weather at planting to kill marestail with Ignite.”


Glyphosate-resistant pigweed — recently found in neighboring Mississippi County — is “absolutely” the greatest weed fear for the operation, says Larry. “That's the next bugaboo, considering how prolific those are.”

The good thing is if farmers earnestly try to head it off, “it'll take pigweed five years to expand into the problem marestail can make in one,” says Brent. “Pigweeds just don't have the mobility. That's working in our favor.”

And Roundup Ready technology must be protected. When it first came out, “everyone was saying, ‘Man, this is great. We're going to be spraying Roundup and then going to the lake on the weekend.’ Now, everyone knows what can happen…Nature always wins — always.”

Still, there are producers who cut rates of glyphosate, something Brent has trouble understanding. “Do you go duck hunting to cripple a duck? No! You go to kill them. I don't want them quacking in the boat. Why would anyone put out 18 ounces of Roundup? They may be saving a few pennies, but they're cutting their own throats…”

Brent likens glyphosate to “a crescent wrench that fits (nearly) every bolt on the farm. It may not be the best tool every time but it sure does help out when you're on the back 40 and all you've got is a flathead screwdriver.”

This year, the Hendersons will be planting Roundup Ready Flex cotton — but not major acreage. “When Flex first came out, Dad said, ‘We need to use Flex on our farm to help us. We aren't going to abuse it. We're not going wall-to-wall with Roundup. But we need to put it in fields that are farther away.’ That will save time and mean fewer trips. Flex will work perfectly there, but we're still going to use residuals. But instead of going over there with three tractors and hooded sprayers and taking all day, we'll just take a hi-boy with a 90-foot boom and spend three hours. That'll really help us. In the future, we may move the Flex to other areas of the farm. It's just more options.”

In late April, Brent was talking to a cotton farming friend from Virginia and offered a warning. “Roundup Ready is working great for them. They have no resistance issues. But I told him, ‘You need to preach that y'all need to change chemistries. You don't want to get into a situation like we're in.’ Arkansas is being hammered with (resistant) marestail. What comes next?”

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