CHESTERFIELD, Mo. — The United Soybean Board (USB) will be expanding its Take Action program, which in addition to combating herbicide-resistant weeds will now be tackling fungicide resistance in soybeans.

 

“Herbicide resistance is a significant issue farmers face in their fields,” University of Kentucky extension plant pathologist Carl Bradley said at the 2017 Commodity Classic, earlier this month in San Antonio, Texas, where the program expansion was announced. “It’s possible that fungicide resistance is going down the same path. Now is our chance to get ahead of it before it gets too severe.”

 

Spearheaded by the soy checkoff, Take Action advocates a diverse approach to weed management to avoid resistance, especially regarding disease management.

 

“To stay ahead of fungicide resistance, we can’t cut corners,” said Gregg Fujan, USB Supply Action Team chair, Nebraska Soybean Board chair and Weston, Neb., farmer. “We believe a well-rounded method of pest management is needed to preserve existing technology and protect farmers’ long-term profitability.” If not addressed soon, he said farmers risk losing the few fungicides they now have available.

 

“If we lose the tools we have, there’s a financial risk of having diseases we can no longer control.”

 

Bradley said many farmers may believe a fungicide application will give a bit of a yield bump – even if diseases are not at economically damaging levels.

 

“But if they’re applying fungicides no matter what, they’re beginning to chip away at the tools they have to fight yield-damaging pathogen outbreaks,” he said. “We want to encourage farmers to be mindful of what they’re using and when, so they don’t lose what they have.”

 

On March 23, the Iowa Soybean Research Center (ISRC) hosted its second Think Tank at the Iowa State University Alumni Center. More than 30 farmers, ISU researchers and Iowa Soybean Assoc. (ISA) and center staff discussed ways to increase production and profitability.

 

Clarke McGrath, ISRC on-farm research and extension coordinator and ISU extension agronomist in Harlan, explained the Think Tank is where farmers and researchers determine what projects to fund via the ISRC each year. He said the recent Think Tank is where the newly-created Iowa Pest Resistance Management Plan (IPRMP) was launched.

 

“It’s an Iowa-specific plan to address pests like weeds, insects, diseases and nematodes that can adapt and become resistant to chemical, genetic and agronomic control practices,” he noted. “Resistance management work is something we have consistently put resources towards from our start, including our participation in the IPRMP.

 

“The IPRMP outlines our recommended integrated management plans that will sustainably control pests. We are also developing and promoting more methods to help detect pest resistance. If we are on the ball and catch it early, resistance can be delayed or even prevented, limiting the spread of pest resistance.”

 

McGrath said though “we’ve been fighting them for decades,” herbicide resistance in weeds wasn’t getting a lot of attention until “glyphosate-resistant waterhemp started creating so many problems, so the issue got ahead of us.

 

“Now with so many fields across Iowa that have a wide variety of problem weeds that are becoming resistant to more herbicides over time, a majority of growers and agronomists recognize the problem and are taking steps,” he added.

 

“We are on the forefront of the same thing with insects, nematodes and diseases

in many ways. The USB putting some additional emphasis on diseases illustrates that pretty well – if we aren’t careful, we will without a doubt have resistant

pathogens in Iowa.”

 

However, he said there are some challenges with diseases that will make it really tough to head off resistance. “Disease pathogens like fungi are incredibly adaptive and, with so many generations in a season, evolutionary processes like resistance can develop quickly,” he said. “And unlike weeds, it is pretty hard to visually assess if a fungal pathogen has been controlled by a fungicide or if resistance is developing.

 

“Last I knew, 2016 results from testing of frogeye leafspot from Iowa fields isn’t completed yet, so we are not sure of the extent of any resistance last year in Iowa. But with 12 other states having fungicide-resistant frogeye, it could be an issue here in short order.”

McGrath said frogeye is just one example.

He offered growers advice to help hold off resistance:

 

•If you are in an area prone to fungal diseases, select varieties based on resistance

to the pathogen

•Use crop rotation

•Scout and properly identify diseases to avoid unnecessary fungicide applications

•Spray fungicides when needed

•Use the right rate; cutting rates is the fast track to resistance

•Select products with multiple modes of action

•Rotate modes of action

 

“The scientific answer to holding off fungicide resistance is to not spray for any other reason than for economically-justified disease levels,” McGrath said. “Some growers feel that they gain significant economic returns from plant health or yield-enhancing fungicide applications, so the economic answer for those operations might be to spray regardless of disease pressure.

 

“I get asked on a pretty regular basis about these two concepts. The short answer is that I don’t have an answer to reconcile them. It comes down to a fieldby-field, grower-by-grower and year-to-year decision.”