From Cotton Grower Magazine, By Jim Steadman – April 2016. Second in a series on influences providing optimism for cotton’s future.
As growers head to their fields this spring, they may have a certain sense of déjà vu. Despite well fought battles against pigweed and other weeds in 2015, the pests are still lurking and waiting in many fields. Same goes for insects, too.
Over the past few years, the list of products available to fight the fight has gotten shorter due to resistance and, increasingly, regulation and registration issues. It’s the stuff that keeps growers, consultants, entomologists and weed specialists up at night. But, there is some help coming.
New Herbicide Products and Technologies
Larry Steckel can recite the history of weed resistance quickly.
“We lost Treflan in the 1980s,” states Steckel, University of Tennessee Extension weed specialist. “We lost ALS inhibitors in the mid-1990s, and we lost full glyphosate control almost a decade ago. And now, we’re starting to lose PPO products.”
Yet, in spite of the limited choices available, cotton growers in many areas did an admirable job of managing Palmer pigweed in 2015. Growers do have glufosinate (Liberty) as a backstop, since it can be applied over the top on most newer cotton varieties. Yet, as Steckel points out, growers are going to start losing traction with the PPO products.
“We’ll need to start leaning on some of the other herbicides available, like Dual and Warrant,” he says. “Cotoran and Caporal are also still in play.”
Two additional tools for resistant weed control – dicamba products for use with Monsanto’s Bollgard II XtendFlex system, as well as Dow AgroScience’s Enlist Duo (2,4-D Colex-D technology) – are still undergoing regulatory scrutiny. Steckel is hopeful to see clearances on those products this year.
A new recently-registered addition to the pigweed fight is Brake herbicide (fluridone), which will be available in two premix formulations – Brake F16 (fluridone and fomesafen) for the Southeast and Brake FX (fluridone and fluometuron) for the Mid-South and Southwest.
“Brake is a bleaching herbicide that turns pigweed white after they come up,” explains Steckel. “It’s absorbed through the roots, and cotton tolerance is very good. It would also be a very good fit for conventional cotton. It will provide decent, long residual where growers don’t have Liberty available.”
Next Generation of Bt Technologies
Cotton growers rapidly adopted Bt technology after its introduction in 1996. Today, over 95% of all cotton planted in the U.S. contains one of the available technologies.
“Our Bt cottons perform remarkably well,” says Scott Stewart, University of Tennessee Extension entomologist. “Technologies like WideStrike3, Bollgard II and TwinLink provide a lot of protection and are what we have to work with this year.”
Soon, however, the next generations of these traits will be coming to market. And, notes Stewart, that means improved control of bollworm, fall armyworms and other worm pests.
“For example, WideStrike3 is a big step up from the original WideStrike,” he says. “Statistically, we’ve also seen increased plant protection in our 2015 tests for TwinLink Plus and Bollgard III.”
Neither TwinLink Plus nor Bollgard III will be commercially available in 2016, but are on the horizon for upcoming seasons. WideStrike3 is available in certain PhytoGen varieties. Yet in spite of increased efficacy, Stewart reminds growers that none of the technologies are bulletproof, especially under high worm pressure. Two years of field testing still shows significant yield increases from additional insecticide treatments.
“I still feel comfortable using pyrethroids tank-mixed with products like orthene to help manage bollworm with our Bt technologies, because we’re also going to be making those applications for plant bugs” says Stewart.