Herbicides
Using several herbicides with multiple modes of effective action are essential in combatting resistance, minimizing the weed seedbank and preparing fields for success. A planned herbicide program using multiple modes of action is the best strategy for these tough-to-control weeds.

An herbicide that offers multiple modes of action to help manage a variety of broadleaf weeds that can also be used in various tank-mixes to control glyphosate-resistant species will help address the challenges of weed resistance in both the current and future growing seasons. 

For example, last year, a group of growers in Eastern Canada tested Armezon PRO, a new Group 15 and Group 27 herbicide. With a wide application window from early post-emergence to the eight-leaf stage in glyphosate-tolerant corn and the ability to easily tank-mix with additional products, growers were able to customize their weed management to meet their needs. When tank-mixed with atrazine in glyphosate-tolerant corn, Armezon PRO provides four modes of action.

Customizing weed management strategies is especially useful when weather prevents getting into the field for a pre-emergent application.
Managing problem weeds with multiple modes of action provides residual activity, reducing the weed seedbank and setting up fields for the next season. 
Premier Tech, an international leader in active ingredients for sustainable agriculture and horticulture, will take the lead in the final steps to bring to full scale the manufacturing and commercialization of a selective bioherbicide. In January, the Horticulture and Agriculture Group signed a license agreement with Agriculture and Agri-Food Canada (AAFC) to finalize the development and commercialization of a product formulated from an indigenous fungus (Phoma macrostoma).

Over nearly ten years, the federal department invested millions of dollars in research on this fungus and its compounds (macrocidins), which can eliminate broadleaved weeds, particularly dandelions. This breakthrough discovery has been patented in several countries and is commercially registered in the U.S. and Canada.
The late harvest in fall 2016 created more than just delays in crop removal – fields were dirty with weed growth and there was limited time for fall herbicide application. As a result, many farmers are expecting weedier fields this spring and will need to be diligent in using the best weed control strategies including pre-seed herbicides and the best in-crop solutions.

To assist farmers in what will likely be a more challenging spring battle with weeds, Dow AgroSciences has announced that the Diamond Rewards herbicide offer that was previously only available to Nexera customers will be open to all growers seeding any Roundup Ready and Clearfield canola varieties this spring.

Effectively immediately, with a minimum purchase of 240 acres (6 cases) of Eclipse, any Roundup Ready canola grower can qualify for the $2.00 per acre rebate. Similarly, with a minimum purchase of 240 acres (6 cases) of Salute, any Clearfield canola grower can qualify for the $2.00 per acre rebate.

Nexera canola growers will continue to receive the rebate with no minimum purchase requirement. Farmers must be registered for the Dow AgroSciences Diamond Rewards program and purchases must be made between December 1, 2016 and November 30, 2017 to qualify.

Click for more information on Eclipse and Salute.  
Just over 20 years ago, researchers initiated the first bioherbicide research and development program in the country at Agriculture and Agri-Food Canada (AAFC) in Saskatoon. Led by Karen Bailey (who recently retired), the program has made significant advancements in bioherbicide development for horticulture and turf crops, and more recently, promising solutions for agriculture. Bioherbicide product development is a welcome addition to the integrated weed management toolbox for crop production. Biopesticides are classified as “reduced-risk” products by the Pest Management Regulatory Agency (PMRA).
Gowan Canada has added volunteer canola to the Permit WG Herbicide label in time for spring 2017.

Permit is registered for pre-emergent and post-emergent use in dry beans, and post-emergent use only in corn. Data generated by independent contract researchers has consistently shown high levels of extended residual control of volunteer canola from both pre and post-emergent applications.

For more information on Permit for volunteer canola, growers are urged to contact their local retailer.
New herbicide product registrations and label updates continue to bring more choice to farmers, with multiple modes of action to manage weed infestations and herbicide resistance. The following product information has been provided to Top Crop Manager by the manufacturers.
Mississauga, ON – Corn growers in Eastern Canada now have a new tool for fast and hassle-free weed control. DuPont Crop Protection announced that approval has been granted for registration of DuPont Destra IS herbicide.

Destra IS is a post-emergence corn herbicide with one-pass broad-spectrum knockdown and residual control, and adds two additional modes-of-action to a glyphosate tolerant system – there’s also residual control and multiple modes of action. The herbicide will allow growers to control hard-to-kill broadleaf and grassy weeds and to keep corn weed-free during the critical weed-free period.

Destra IS has a wide window of application, allowing growers to apply up to the eight-leaf stage, with excellent crop safety and a broader geography, including short season areas. It offers a smaller, easy-to-handle package and compact dry formulation, and is the only dry mesotrione formulation on the market. It offers a faster pour and bottle cleanout.

Fore more information visit Dupont.ca
SASKATOON – Western Canadian corn growers now have a new tool to remove early season weed pressure to help maximize yield and profits in corn. DuPont Crop Protection has announced that approval has been granted for registration of DuPont Sortan IS herbicide.

DuPont Sortan IS herbicide will allow growers to control tough, yield robbing weeds, such as volunteer Roundup Ready canola, wild buckwheat, redroot pigweed (including triazine-resistant biotypes), lamb's-quarters, green foxtail, barnyard grass, and quackgrass, to keep corn weed-free to maximize yield and profits.

An additional mode of action to glyphosate, Sortan IS offers application flexibility – it can be applied pre-emergent or post-emergent, and provides extended control throughout the critical weed free period. For optimum weed control, it is recommended that Sortan IS be tank-mixed with glyphosate herbicide at 900 g ai/ha for control of additional weeds.

Sortan IS will be available at local retailers in Western Canada for the 2017 season.

For more information, visit dupont.ca
Lentil and canola growers in Western Canada have new options for burndown weed control with new herbicide updates from Nufarm Agriculture Inc. Valtera is now approved for a fall application prior to seeding lentils (large green and small red types).

Valtera (Group 14) is a distinct mode of action that can be used as part of a fall burndown program for residual weed control where lentils will be planted the following crop season. Valtera controls a range of broadleaf weeds including pigweed, lamb’s-quarters, seedling dandelion, kochia and chickweed, and suppression of green foxtail and volunteer canola. Valtera re-activates with moisture to deliver residual control that lasts for four to six weeks in the spring. Valtera is also registered for spring or fall pre-seed burndown and residual control in chickpeas, field peas, soybeans and spring wheat. Visit nufarm.ca for more info.
Axter Agroscience has improved the performance of CropBooster with the addition of specific organic acids and micronutrients to create CropBooster 2.0. These modifications generate a significant yield increase.

CropBooster 2.0 in the herbicide tank mix produced an average yield increase of 3.3 bushels of wheat per acre in multiple field trials. In these same experiments, CropBooster 2.0 performed better than the original CropBooster with a higher yield increase.

By allowing crop plants to restart growth or to continue growing more quickly, CropBooster 2.0 is also proven to increase yields without reducing weed control.

Click here for more information.

FMC of Canada has announced a new expanded label for Authority 480 herbicide. The new label features more registered weeds and additional crops, according to a press release.

The weeds include eastern black nightshade, a particularly troublesome weed for identity preserved (IP) soybeans, and common waterhemp – the newest glyphosate-resistant weed in Eastern Canada. There are 13 weeds on the new expanded label, such as red root pigweed, lamb’s-quarters, wild buckwheat, eastern black nightshade, common waterhemp, yellow woodsorrel, common groundsel, cleavers (suppression), Powell pigweed and common purslane.

Authority offers a new group 14 weed control option for group 2 and glyphosate resistant weeds. 

Several new specialty horticulture crops have also been added to the Authority herbicide label, including chickpeas, field pea, flax and sunflowers. 

August 24, 2016 - Command, a herbicide from FMC, is now registered for control of cleavers in canola.
 
Command is a Group 13 pre-emergent herbicide that will provide canola growers with residual control of cleavers and will be an integral part of an overall cleaver management program in canola.  It is a liquid formulation that can be tank-mixed with glyphosate for a one pass pre-seed application. 

Command can be used with any canola herbicide system.
 
You may think weeds resistant to herbicides are a new phenomenon linked to the overuse of glyphosate in genetically engineered crops, but according to the Weed Science Society of America (WSSA) nothing could be further from the truth. This year marks only the 20th anniversary of glyphosate-resistant crops, while next year will mark the 60th anniversary of the first reports of herbicide-resistant weeds.

The first known report of herbicide-resistance came in 1957 when a spreading dayflower (Commelina diffusa)growing in a Hawaiian sugarcane field was found to be resistant to a synthetic auxin herbicide. One biotype of spreading dayflower was able to withstand five times the normal treatment dosage. That same year wild carrot (Daucus carota) growing on roadsides in Ontario, Canada, was found to be resistant to some of the same synthetic auxin herbicides.

Since then, 250 species of weeds have evolved resistance to 160 different herbicides that span 23 of the 26 known herbicide mechanisms of action. They are found in 86 crops in 66 countries, making herbicide resistance a truly global problem.

“Given all the media attention paid to glyphosate, you would think it would have the greatest number of resistant weed species,” says David Shaw, PhD, a Mississippi State University weed scientist. “Though there are currently 35 weed species resistant to the amino acid synthesis inhibitor glyphosate, there are four times as many weed species resistant to ALS inhibitors and three times as many resistant to PS II inhibitors.”

Scientists say what is unique about glyphosate resistance is the severity of selection pressure for resistance development. More than 90 per cent of soybean, corn, cotton and sugar beet acres in the U.S. are glyphosate tolerant and receive glyphosate treatments – often multiple times per year.

“The sheer size of the crop acreage impacted by glyphosate-resistant weeds has made glyphosate the public face for the pervasive problem of resistance,” says Shaw. “But resistance issues are far broader than a single herbicide and were around long before glyphosate-resistant, genetically engineered crops were even introduced.”

Research shows that resistant weeds can evolve whenever a single approach to weed management is used repeatedly to the exclusion of other chemical and cultural controls – making a diverse, integrated approach to weed management the first line of defense. Many growers have had great success fighting resistance by adopting a broader range of controls.

One example is found in the experiences of U.S. cotton growers in the southern U.S. After years of relying on glyphosate for weed control, resistant Palmer amaranth (Amaranthus palmeri) began to overrun crops and caused yields to plummet. Today integrated weed management programs that use a diverse range of controls have become commonplace in cotton, despite the higher cost. Growers are using cover crops, hand-weeding, tillage, weed seed removal and herbicides with different mechanisms of action in order to keep Palmer amaranth at bay.

There have been tradeoffs. Additional herbicides, labor and fuel have tripled the cost of weed control in cotton. In addition, increased tillage has raised concerns about soil erosion from water and wind.  But for now, the crop has been preserved.

“Although diversification is critical to crop sustainability, it can be difficult to make a decision to spend more on integrated weed control strategies,” says Stanley Culpepper, PhD, a weed scientist at the University of Georgia. “As a result, many of the most successful diversification efforts can be found in crops like cotton where change became an imperative.”

Culpepper says that in addition to costs, another barrier to adoption of integrated weed management is the belief by some that new types of herbicides will be invented to take the place of those no longer effective on resistant weeds. But the HPPD-inhibitors discovered in the late 1980s for use in corn crops are the last new mechanism of action to make its way out of the lab and into the market.

“It would be naïve to think we are going to spray our way out of resistance problems,” Culpepper says. “Although herbicides are a critical component for large-scale weed management, it is paramount that we surround these herbicides with diverse weed control methods in order to preserve their usefulness – not sit back and wait for something better to come along.”

Weeds defend themselves from control measures in many ways, and can adapt to our cropping systems. A winter annual cleavers is avoiding herbicide control because it germinated in fall and will be too large and difficult to kill before an herbicide is applied in the spring. Buckwheat is naturally tolerant to glyphosate, although it is not resistant. Stork’s bill can be a winter annual but it is also morphologically plastic and keeps germinating all season long. Herbicide resistance is another way a plant defends itself.

For me, the world’s greatest herbicide was – and I say that in the past tense, was – glyphosate. It’s unfortunate but in my geography it is a herbicide of the past on many driver weeds. For me Palmer amaranth is a driver weed. For you that may be kochia. That may be wild oat. That could be green foxtail.

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