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No New Row-Crop Herbicide Sites of Action Coming, Say Weed Scientists

Corn and Soybean Weed Management Must Move Beyond Herbicides.

Each year, weed scientists from across the Midwest meet for the North Central Weed Science Society (NCWSS) meeting. Here are three points they have discussed so far this week at the NCWSS meeting St. Louis, Missouri.

• Farmers want new herbicides and new herbicide site of actions. That’s the message that they, industry representatives, and retailers had in seven 2016 and 2017 USDA listening sessions, says Jill Schroeder, and agronomist and weed scientist at USDA-ARS-Office of Pest Management Policy.

“This came as a surprise,” says Schroeder. “This is contrary to a lot of messaging that has come out of this organization and every other regional society.”

That’s because new herbicide sites of action aren’t coming for a long time in the corn and soybean space. 

New herbicides have been developed and marketed in the last several years. It’s just that they are mixes of established herbicide sites of action. HPPD inhibitor herbicides (Callisto, Balance Pro) were the last novel site of action commercialized in the early 1990s. Since then, there’s been nothing.

“I don’t see anything coming for 15 to 20 years down the road,” said Mike Owen, Iowa State University (ISU) Extension weeds specialist, to those attending last week’s ISU Integrated Crop Management conference. “Weed management must move beyond herbicide management. This includes cultural practices like seedbank management.”

• Intelligent weed removal is coming. A Danish company, F. Poulsen Engineering, is developing robots for mechanical weeding for both organic and conventional agriculture, notes 
Lee Van Wychen, science policy director with the Weed Science Society of America. 

Meanwhile, Blue River Technologies (recently bought by John Deere) is developing technologies like See and Spray. This combines engineering and computer technologies to selectively apply herbicides only when needed. This can cut herbicide costs by 90%, according to the company.

• There’s a good reason why applicators should regularly change nozzles on sprayers. Winfield United scientists analyzed wear patterns of nozzles over two years of use in 2016 and 2017. Over time, chemicals and additives can erode nozzles. This can result in overapplication or underapplication of herbicide and a change in droplet characteristics. 

Worn nozzles in the Winfield United analysis for 2016 and 2016 cost $21,230 over two years due to factors like added cost of chemical. This could have been saved by a $618 investment in nozzle replacement, Winfield United officials say. 

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