Impede weeds

Growers across the Southeast wondered what would replace Deltapine’s 555 in their cotton fields.

Few figured it would be Palmer amaranth, the worst of the worst pigweed.

The virulent weed that’s now popping up with resistance to both glyphosate and ALS herbicides dominates conversations and cropping decisions in those areas where it’s overrunning fields. In other areas, resistant marestail is a deal breaker.

For some, that’s meant a move away from cotton.

Key Points

• Growers look to weed control when deciding cropping plans.

• By 2013, 1 in 4 acres may have glyphosate-resistant weeds.

• Agronomics still underpins every seed buying decision.


“The acreage of corn in the South has taken a fairly good-sized jump in the last couple years, not surprisingly in conjunction with a drop in cotton acres,” says Mike Hughes, Pioneer’s agronomy research manager for the Southern business unit. “From my standpoint, corn would be an attractive crop to these guys that have been growing cotton and have seen a rise in resistant weeds.”

Corn is attractive for fields overloaded with weeds in large part because atrazine is a powerful weapon against weeds. Syngenta technical brand manager Chuck Foresman points out that atrazine has high efficacy against the toughest weeds — pigweed, giant ragweed, morningglory — and enhances grass control in pre-mixes.

“Atrazine has great residual performance,” Foresman says. “Without residual, growers would be out there making an application after every rainfall.”

While the heaviest glyphosate-resistant Palmer amaranth infestation is in central Georgia, Foresman cautions growers to take steps now to thwart resistance. Nine glyphosate-resistant biotypes are identified in 22 states at this point, he says.

“We could end up with 1 in 4 row-crop acres infested with a glyphosate-resistant weed by 2013,” Foresman warns.

Growers who haven’t found resistant weeds in their fields still focus their cropping decisions on agronomic performance of a cotton variety.

“If the weed control is there, it’s just having a variety,” says University of Georgia Extension agronomist Jared Whitaker. “If growers use pre- and postemergence herbicides, then they’re already ahead of the ballgame.”

The key is to weigh both factors — regardless of whether those weeds that grow like teenagers are in a given field.

“Growers certainly do not want to give up any agronomic performance or weed control potential,” says Andy Hurst, Bayer CropScience product manager for herbicide-tolerant traits and Ignite herbicide. “They want the best solution for weed management that’s going to yield the most.”

Another factor in choosing cottonseed is price, including technology fees, and herbicide and insecticide costs. The graph offers a comparison of prices for the technology packages offered based on 2009 prices.

As always, growers have a deep bench from which to pull their lineup for the 2010 season.

The list at left includes the top two variety picks from each of the four major cottonseed lines — Deltapine from Monsanto, PhytoGen from Dow AgroSciences, and FiberMax and Stoneville from Bayer CropScience. Expect more releases as the season nears.

Top cotton options

Southern Farmer asked Bayer CropScience, Monsanto and Dow AgroSciences for the top two picks for Southeast growers in each of their cottonseed lines. Here they are:

Deltapine

DP 0935 B2RF is a midmaturity Bollgard II and Roundup Ready Flex stacked variety that offers consistent high yield potential with smooth leaf and nectarless trait.

DP 0949 B2RF is a mid- to full maturity Bollgard II and Roundup Ready Flex stacked variety that offers high yield potential and outstanding fiber quality.

FiberMax

FM 1735LLB2 is an early/medium maturity LibertyLink and Bollgard II stacked variety with a medium height plant type. It has very good early-season growth, but does not need aggressive Stance plant regulator usage in most situations.

FM 1845LLB2 is a medium/full maturity LibertyLink and Bollgard II stacked variety that provides excellent fiber quality with high yield potential.

PhytoGen

PHY 370 WR is an early maturity WideStrike Insect Protection and Roundup Ready stacked variety with good vigor, broad adaptation and high yield potential.

PHY 375 WRF is an early maturity WideStrike Insect Protection and Roundup Ready Flex stacked variety with excellent vigor, broad adaptation, high yield potential, and very good to excellent fiber quality.

Stoneville

ST 4288B2F is an early/medium maturity Roundup Ready Flex and Bollgard II stacked variety that offers excellent seedling vigor, resulting in consistent stand establishment, excellent yield potential and very good fiber quality.

ST 5288B2F is a medium maturity Bollgard II and Roundup Ready Flex stacked variety that offers excellent seedling vigor, sets a high level of fruiting nodes, and has excellent yield potential and good fiber quality.

Check out land-grant trials

Cotton Incorporated offers Web links to cotton variety trial results in 17 states at www.cottoninc.com/AgriculturalResearch/StateVariety
TrialData
. Performance data includes lint yield, fiber quality traits and other important agronomic traits.

Additionally, the site offers the COTVAR: Variety Comparison Tool, a Web-based program that may be used to summarize cotton variety performance data from state cotton variety tests conducted in five Mid-South states. Development plans are in progress to add states in the future.

Growers discuss their variety picks for 2010

Nick McMichen,
Centre, Ala.

“I have always been a big proponent of trying and planting newer varieties. ... I have been doing a variety test with [Auburn University Extension cotton specialist] Charlie Burmester for 18 years and think that this information is very valuable for myself and my neighbors as far as variety selection. But for the last two years I have been fortunate enough to have been able to put in a New Product Evaluator trial with Deltapine. In this I have been able to see and evaluate the newest of their varieties. Last year I got to see firsthand 0912, 0920 and 0924, and the results were a substantial increase over older varieties. This year I have seen similar results, but the varieties that I evaluated have not been given official numbering yet. I plan to plant two of the three unnamed varieties along with 0912 and possibly some 0935.

I feel like we are about to break the glass ceiling on yields and fiber quality with improved varieties and genetics.”


Anthony Martin,
Millen, Ga.

“I’m going to stick with FM 1845LLB2. It’s about $100 cheaper a bag than Triple Nickel. You can take that money and spend it on chemical. ... I used a 6-inch seed rate this year. I think I’m going to go to 7 next year. ... I may plant more cotton and less corn. I didn’t put anything down with Ignite preplant this year. I’m going to put down Reflex or Prowl next year.”


Bill Bridgeforth,
Tanner, Ala.

“We think we’re going to go back to being cotton farmers. We think the market is just about there, and it’s going to buy some acres come spring. We don’t have any problems with resistant weeds. Everything we plant we use a residual herbicide. We’re looking at DP 924 B2RF and Stoneville, one of the B2 Flex varieties; I can’t remember the number. Stoneville and [Deltapine] just have competitive varieties. We try to choose varieties that do well all across the Cotton Belt.”

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DOCTOR OF PALMER AMARANTH: UGA Extension agronomist Jared Whitaker wrote his doctoral dissertation on glyphosate-resistant pigweed. He advises cotton growers to start with a combi-nation of preemergence herbicides. Then, he says, “you still need a Dual or Staple mixed with Roundup or Ignite [depending on variety] applied early for control to last. These early post-[emergence] residuals extend that window of control so that you can get to layby.”

Growers swing at pigweed with Ignite on WideStrike

It’s controversial. It breaks rules, but not laws.

Some call it a rescue operation. Some call it salvation.

It’s the practice of using Ignite on cotton with the WideStrike technology.

Ignite is a glufosinate-based herbicide offered by Bayer CropScience and labeled for cotton and several other crops. WideStrike is a proprietary two-gene insecticide technology offered in PhytoGen cotton varieties by Dow AgroSciences. Neither company endorses using Ignite on WideStrike.

“What we have in the marketplace is a semi-tolerant event to Ignite, but one that’s not up to specifications as far as Bayer’s criteria for commercial tolerance,” says Andy Hurst, Bayer CropScience product manager for herbicide-tolerant traits and Ignite herbicide. “Bayer does not warrant the use of Ignite over the top of PhytoGen, WideStrike, varieties.”

Key Points

• Growers take risk when using Ignite on WideStrike cotton.

• Ignite burns WideStrike and kills other cotton.

• Ignite kills Palmer amaranth that’s shorter than 3 inches.


Neither does Dow.

Dow General Manager and PhytoGen cottonseed market specialist Duane Canfield says, “All risk of crop damage and loss associated with the use of GA [glufosinate ammonium] herbicides on WideStrike cotton remains solely with the user.”

For some growers in Macon County, Ga., that’s a risk they’re willing to take.

Although neither Macon County Extension agent Jeremy Kichler nor the University of Georgia recommends Ignite on WideStrike cotton, Kichler shares some of the management tactics his growers are adopting.

Growers are using the 29-ounce rate of Ignite, applied with a flat fan nozzle, he says. They’re also using a residual, whether it’s Treflan, Prowl, Cotoran, Staple or Reflex. And some are mixing Dual at 1 1/3 pints with Ignite, even though Kichler notes that mix increases burn on the cotton leaves.

Essentially, he says, Ignite gives “a little wider window to get your residuals activated, which can be very beneficial especially in dryland production.”

“You still have to be timely with it,” he says. “Growers need to spray when Palmer is 3 inches or less.”

Some growers are using FiberMax LibertyLink varieties. The ones who moved to WideStrike did so to be able to continue using Roundup on grasses, Kichler says. “It’s about flexibility,” he says.

Bayer is developing cotton varieties with resistance to glyphosate and glufosinate. Southeast growers can look for GlyTol plus LibertyLink varieties stacked with TwinLink, a two-gene Bt trait, in 2012.

Allow burn, beat pigweed

The study “Weed Control and Crop Response to Glufosinate Applied to PHY 485 WRF Cotton,” reported in Weed Technology 23, July-September 2009, demonstrated that “visible injury to PHY 485 WRF was consistently observed five [days] after application, but the cotton recovered and yield was not reduced.”

The injury was as high as 22% in one protocol, according to the study released by North Carolina State University’s Alan York and University of Georgia’s Stanley Culpepper, Phillip Roberts and Jared Whitaker. The treatment, however, also consistently killed 97% of the Palmer amaranth.

Ultimately, the researchers concluded: “A cultivar with tolerance to both glufosinate and glyphosate also gives growers an additional and much-needed tool to use in resistance-management strategies to avoid or delay further selection for glyphosate or ALS-inhibitor resistance. Until agronomically adapted cultivars with multiple herbicide-resistance traits become available, glufosinate-based systems in PHY 485 WRF cotton could fill a void in current management systems.”

Not the same as 555

Hit it hard with the Pix. Max out the Stance. Don’t let it get away from you.

Those all are admonitions growers heard — and shared with each other — as DP 555 BGRR was planted on more and more cotton acres in the Southeast.

“How you managed 555? Just forget about it,” says Bayer CropScience’s Jeff Brehmer of the FiberMax and Stoneville lines. “These are not that aggressive.”

Same goes for the new Deltapine varieties, says Monsanto’s Dave Albers. “PGR management of Deltapine Class of 09 and Class of 10 varieties is not as intensive as with DP 555 BGRR.”

Finally, University of Georgia Extension agronomist Jared Whitaker reminds growers: “There is a chance that we could hurt yields of new varieties with too much Pix. These varieties don’t grow like 555. We’re going to have to manage the crop closely and consider being lighter on our early-season PGR applications.”

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HOME OF G-R PALMER: Jeremy Kichler showed up at the University of Georgia Extension office just in time for the war that threatened to end all cotton fields: farmers vs. glyphosate-resistant Palmer amaranth. An unconventional approach — using Ignite, which is designed for LibertyLink varieties, on varieties with WideStrike, which is a two-gene insecticide technology — is helping growers survive.

This article published in the January, 2010 edition of SOUTHERN FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.