Protecting Cereals Yield and Investment by Controlling Weeds

When Monte Anderson looks out across the fields of eastern Washington, he sees the perfect environment and moisture patterns for growing high-yielding, dryland cereals. 

“We grow a lot of soft, white winter wheat that’s for export, and that’s why growers will invest major dollars to keep weeds under control,” he says. Anderson is a principal agronomist for Bayer, who works with growers and crop advisers throughout the Pacific Northwest. 

“Normally people think about grassy weeds as being yield-robbing, but our growers also need to keep a handle on broadleaf weeds, because of the diversity of weeds and the diversity of the slope,” he says. “And they're willing to spend some money, particularly to protect the yield and quality of the winter wheat crop, because it's going to be hundred-bushel wheat or more.”  

Ian Burke, weed scientist at the University of Washington in Pullman, agrees that growers in the Palouse region of eastern Washington and western Idaho recognize the value of using herbicides to manage weeds in wheat “because there's often a very significant return on investment in terms of dollars and ease of harvest. It's quite common for them to use herbicide mixtures that exceed a hundred dollars per acre in the high rainfall zone to control their weeds, because the expected net return on that crop per acre is going to be in the 200 to $400 range.” 

The Cost of Weeds 

In a recent journal article that examined the potential yield loss from weeds in the United States and Canada, Burke and other weed scientists reported on yield loss by agroecological zone (annual cropped, transition, and wheat-fallow). It showed that the greatest yield losses typically occur in winter wheat crops in the wheat-fallow region of the Pacific Northwest.  

“Growers there are sort of on the edge of profitability for wheat production,” Burke says. That means the farmers and farms that are the most susceptible to yield loss from weeds “are the ones who can least afford it.” 

The importance wheat producers place on protecting yields from weed loss is shown by the numbers: more than 97% of the wheat acres in the Pacific Northwest and Northern Great Plains are treated with a herbicide. 

Kevin Thorsness, Bayer crop protection technical representative and one of the Cereal Experts with Bayer, says, “It's well documented that if you don't control your weeds, you're going to lose yield, and you're going to lose money and part of your input investments.”  

Wild Oat, a summer annual grass, in dirt/soilTake wild oat, for example. “If you have approximately 10 wild oats per square yard that are remaining in your wheat field, you're going to lose about 8 to 9% of your yield. The earlier you take out the weeds, the better your yield potential is going to be.” 

Clean fields also mean cleaner, more efficient harvest and higher quality grain. As Burke says, the return on investment in wheat herbicides “is not just about what the weeds are doing to the crop in terms of yield loss, but also harvestability and a host of other issues.” 

Maximizing Profits 

When input costs rise, it’s a common reaction to start cutting back on variable inputs. “We do not want to shortchange the overall weed control power of these programs by whittling away at the needed components to save a few dollars here and there,” Howatt says. “In the long run, that has always shown to be more expensive. Yes, it costs money, but we are investing in the crop. And if we invest appropriately into the crop, then we return the higher profits.”  

Burke encourages farmers to build in cultural inputs and practices that produce a healthy, competitive crop and contribute to weed control success, such as seeding rates, variety choices, nitrogen placement and perhaps changing up tillage programs.  

He also has advice for growers for the 2022 season and beyond when it comes to herbicide economics and selection.  

“There's never really been a better time to know not just the products, but the active ingredients in each one, and think critically about what each one of those active ingredients is doing in the tank for you in every field you're using it on.” 


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