Stacked tolerance traits taking on herbicide-resistant weeds

Next-generation herbicide stacks are on their way to help fight not only weed resistance, but more weed species too

Oilseed Rape Pods

A number of next-generation herbicide-tolerant crops are in the pipeline for soybean and canola growers, but the offerings won’t include any magic bullets. Instead, what we’re likely to see first are more stacked tolerance traits.

It’s because life science companies have their own kind of stacking to deal with. Their new traits are lined up, waiting for the green light from government regulators before they can be released to eager farmers.

Monsanto is among the companies working to get a new soybean offering into the marketplace.

“We are certainly hoping for sales in the fall of 2015 for seeding of Roundup Ready 2 Xtend soybeans in the spring of 2016,” says Joe Vink, weed management technical lead with Monsanto Canada.

Monsanto Canada has received full regulatory approvals in Canada, and got U.S. approval in January, but the launch of the new technology will depend on completing the regulatory process in key export markets.

Roundup Ready 2 Xtend soybean is tolerant to both glyphosate and dicamba, and Vink says its value will be in how those two herbicides complement each other in controlling tough broadleaf weeds. The addition of dicamba could be particularly useful for weeds that glyphosate has traditionally been a little slower to control, like lady’s thumb and wild buckwheat.

Two modes of action on broadleaf weeds also represents good herbicide stewardship, Vink says.  “The goal is to minimize the selection for glyphosate-resistant weeds or herbicide-resistant weeds in general. When you have two highly effective modes of action like glyphosate and dicamba together, that goes a long way in keeping these new tools for farmers available for many years to come.”

Just as important is the fact that dicamba has residual activity in soil, Vink adds. “If you have the two together in a pre-emergence or pre-seed application, for example in a no-till-type of situation, we observe short-term residual on broadleaf weeds, like lamb’s quarters, pigweed, and several other broadleaf weeds as well.”

soybean podsGetting soybeans off to a good start free of early-season weeds maximizes yield potential. Monsanto has run the same experiment at nearly 40 test locations over seven years and says it has found an average 2.4 bu./ac. yield advantage when dicamba was included in early weed removal timing compared to glyphosate alone, Vink says.

“Dicamba is not a full-season residual herbicide, but there’s potential for it to provide enough residual activity on broadleaf weeds so that you can buy yourself some time,” Vink says. “If it is raining or you have a lot of acres to cover, those extra days are a big difference in the spring for many farmers.”

Monsanto plans to offer the stacked trait in a broad maturity range for East and West. While waiting for export countries’ approval can’t be counted as a boon, Vink says it’s giving the company more time to test its germplasm pool.

Meanwhile, Eastern and Western Canada will also get a soybean — and corn — offering from Dow AgroSciences with its Enlist Weed Control System based on new traits and a new herbicide called Enlist Duo, which will include a blend of glyphosate and the new 2,4-D choline formulation.

“The system will allow the farmer to continue to grow corn and soybeans, with an additional herbicide mode of action which is an effective tool to manage hard-to-control and resistant weeds, especially the broadleaf weeds,” says Enlist marketing leader Jeff Loessin.

In Eastern Canada, that will mean effective control of all biotypes of Canada fleabane, common ragweed, giant ragweed, and waterhemp, along with activity on weeds like lamb’s quarters and pigweeds that are difficult for glyphosate to control. In Western Canada, Enlist will be effective on key weeds like volunteer canola, wild buckwheat, smartweed, lady’s thumb, lamb’s quarters, and kochia.

“(Lamb’s quarters and pigweeds) are a couple of weeds in Eastern Canada that if you spray straight glyphosate on them, the control is sometimes less than perfect. Same as wild buckwheat in Western Canada, plus smartweed and even lamb’s quarters,” says Loessin. “Just having that additional mode of action with the 2,4-D in the Enlist Duo herbicide boosts the level of control.”

Dow AgroSciences continues to monitor approval of the Enlist traits in importing countries, but it expects to launch Enlist soybeans in 2016 in Eastern Canada and 2017 in Western Canada, while Enlist corn is targeted for release sometime in 2015 in the East and 2016 in the West.

“The differences between Eastern and Western Canada are based on the breeding programs, and availability of hybrids and varieties,” says Loessin.

Another stacked herbicide-tolerant trait will be coming from Bayer CropScience and MS Technologies, which collaborated to develop Balance GT.

Balance GT soybeans will be tolerant to both glyphosate and isoxaflutole, the active ingredient in the new Balance Bean herbicide. The herbicide’s intended targets are broadleaf weeds and grasses, including eastern black nightshade, waterhemp, ragweed and Canada fleabane. Balance Bean also provides a reactivation feature for coverage from application through canopy closure.

“The Balance GT soybean performance system will give growers a new herbicide mode of action and resistance management option in soybeans, especially for glyphosate-resistant and hard-to-control weeds,” says David Kikkert, business operations manager for soybean seeds and traits.

Balance Bean is registered for use in Eastern Canada and B.C. only, and Balance GT is expected to be available for planting in Canada by mid- to late mid-decade.

The companies are planning to provide additional herbicide trait stacks in the future to allow growers to use three modes of action on one soybean, the first of which will provide tolerance to glyphosate, Balance Bean, and Liberty.

By the end of the decade may come MGI soybeans, which provide pre-emergence exposure to herbicides mesotrione and isoxaflutole, and post-emergence tolerance to Liberty.

Bayer and Syngenta are co-developing MGI, which they consider an important new tool for producers facing challenging weeds like waterhemp, Palmer pigweed and lamb’s quarters.

New for canola

Another Monsanto product focuses on canola. TruFlex Roundup Ready allows farmers to apply Roundup WeatherMAX rates at about double those of first-generation systems, and offers better control of annual weeds and tough perennials like dandelion, foxtail barley and wild buckwheat, plus a wider spectrum of weeds including yellow foxtail, biennial wormwood and common milkweed.

The application window will also extend past the six-leaf stage to the first flower, or 10 to 14 days longer than current technology.

“TruFlex has a higher application rate with a wide application window to provide growers with more flexibility,” says Neil Arbuckle, Monsanto Canada’s strategy lead. “It just provides more flexibility for farmers to ensure that they’ve got good weed control.”

Farmers can use existing applications rates, but as the window gets larger and weeds grow, they have the option to increase the spray rate.

Right now, Monsanto is working through the global regulatory process, and Arbuckle says Monsanto has approval from Canadian regulatory agencies, as well as the U.S., Korea, Japan and Mexico, but is still awaiting approval from Europe and China.

“I think it’s safe to say the industry is somewhat perplexed with the China regulatory approval process for biotech traits,” Arbuckle says. “It has gone from being quite predictable to being more unpredictable, so we are incurring some delays with China’s approvals.”

That’s not unique to canola, Arbuckle says.

Arbuckle hesitates to put a date on when TruFlex will be commercially available, as previous estimates have come and gone. “Let’s just say we hope to be in the marketplace within the next few years. Ideally before 2020.”

Looking ahead, there’s also work being done on both the existing Roundup Ready trait stacked with Liberty as well as a TruFlex Liberty Link option. Beyond that, Monsanto has plans to stack dicamba tolerance with TruFlex.

A non-stacked product will be coming from DuPont Pioneer, which plans on introducing Optimum GLY canola in the next few years.

“DuPont Pioneer anticipates commercialization of this trait later this decade in key canola-growing geographies, specifically Western Canada and Australia, pending key regulatory approvals from export markets globally,” says spokesperson Tara Moir.

The glyphosate-tolerant canola is intended to provide farmers greater marketplace choice, a wider application window, and increased rate flexibility due to higher crop tolerance, Moir says.

In November, Cibus Global and Rotam announced their U.S. launch of non-transgenic SU Canola, which is resistant to Group 2 herbicide sulfonylurea.

“SU Canola offers farmers a new alternative for weed control in canola that will provide sound stewardship options to deal with the management of glyphosate weed resistance,” Cibus’s vice-president of commercial development Dave Voss said in a statement. “SU Canola is an optimal fit for rotation with glyphosate-tolerant soybeans, reducing weed pressure caused by volunteer glyphosate-tolerant canola in soybean fields.”

The product also addresses growing demand for non-transgenic food ingredients, Voss said. But it might not make a widespread commercial splash in Canada for several years due to ongoing regulatory hurdles.

This article was originally published as “Stacking the deck” in the Feb. 17, 2015 issue of Country Guide

Confused yet about stacked technologies?

With an influx of stacked herbicide-tolerant technologies in the offing, there’s the potential for confusion among farmers and advisers.

“Certainly, more education and awareness of growers by both the private- and public-sector researchers and extension specialists is required to minimize any confusion,” says Hugh Beckie, a research scientist with Agriculture Canada and professor at the University of Alberta.

Oilseed specialist Murray Hartman at Alberta Agriculture adds there could be some confusion over herbicide modes of action, best timing, specific weed strengths and weed resistance.

“I suspect that initially industry will take the charge on educating, since governments tend not to focus on management of individual products,” Hartman says.

“A lot of it is going to depend on the extension effort,” adds Robert Gulden, professor in the University of Manitoba’s plant science department. “There are venues where that information could be relayed. Certainly, academics have their role to play in that, as does industry, as do provincial extension services.” It’s a topic that will come up at winter meetings, especially as these products get closer to release dates. “And there’s going to be a learning curve,” Gulden says.

Christian Willenborg, a professor at the University of Saskatchewan’s department of plant sciences says that the more traits that are present in a variety, the more likely it is to add confusion.

“Having said that, the extra confusion comes with added benefits, namely improved pest management of some form. So growers will have to weigh the cost of acquiring new information about stacked traits versus the benefits they confer in the field,” Willenborg says.

There could be an impact on stewardship if growers aren’t fully aware of the science governing the utility of the traits and the requirements surrounding their use, Willenborg says. “A breakdown in stewardship could lead to increased pesticide resistance if traits are not used properly.”

Willenborg believes it’s incumbent on growers to familiarize themselves with the technology they’re using in their systems, but adds it’s also critical agronomists and industry personnel work with them to manage the technology and encourage stewardship of the traits.

“No one knows their fields like a grower does, and they are aware of the specific problems and should therefore choose their seed accordingly. However, a more concerted effort on the extension front is required as seed technology evolves into a more complicated array of traits,” says Willenborg, adding this will require a joint effort between industry, government extension personnel, and scientists.

Agricultural technology has advanced at a dramatic pace over the last decade, and Willenborg believes public institutions need to invest more in extension efforts to address growers’ issues. Still, he adds that during the same 10 years “exponential growth” of highly qualified agronomists has occurred, and they’ve been able to share their knowledge with farmers on technical and practical levels.

Gulden stresses that even with these new technologies, farmers are still going to have to think about integrated weed management.

The systems will present opportunities for greater herbicide use, herbicide mixtures and using a broader array of herbicides within a crop — which theoretically are good management tools to mitigate herbicide resistance — but “we need to think bigger than that with all technologies that we use in terms of weed management, and strive to aim for more of an integrated approach to suppress weeds.”

Gulden adds that while stacked traits open opportunities for more than one mode of action, that doesn’t necessarily mean farmers need to spray all the herbicides a seed is resistant to in one year.

“Weed spectrum and weed control needs should drive some of that, and not just a blanket application of everything all the time,” Gulden says.

Another concern may be that a double-stacked HT in the best genetics could become so popular that a couple of varieties would dominate the marketplace, says Hartman.

Not only would that limit market competition, but it could also limit diversity in farm fields and thus make them more prone to biotic or abiotic shifts.

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