Fungicide Resistance Found In Soybean Field

Research conducted by the University of Illinois (U of I) and the University of Tennessee confirms that the fungus that causes frogeye leaf spot (FLS) of soybean, Cercospora sojina, has shown resistance to strobilurin fungicides in a Tennessee soybean field.

“Strobilurin fungicides belong to the chemistry class known as the quinone outside inhibitors (QoIs), which are the most widely used group of foliar fungicides applied to field crops to manage plant diseases,” says Carl Bradley, U of I Extension plant pathologist.

These fungicides can be sold as one-active ingredient products such as Headline (BASF Corp.) or Quadris (Syngenta Crop Protection) or in products that combine them with a fungicide in a different chemistry class known as the demethylation inhibitors, sometimes referred to as triazoles, he says. Products that include a strobilurin-triazole combination of active ingredients include Quilt (Syngenta Crop Protection) and Stratego (Bayer CropScience).

Strobilurin fungicides have been deemed high risk for fungal pathogens developing resistance to them. This high-risk status has been determined by the Fungicide Resistance Action Committee (FRAC), an international committee that evaluates fungicides’ likelihood of developing resistance.

“Plant pathogenic fungi developing resistance to strobilurin fungicides is not new,” Bradley says. “This has already occurred in potatoes and other crop and disease systems where multiple fungicide applications occur during the growing season.”

In the major soybean production areas in the U.S., soybean fields are generally treated once during the season with a fungicide (if treated at all), Bradley says.

“However, we were somewhat surprised to find resistance so soon,” he adds. “Every time you apply a fungicide, you increase the selection pressure and the opportunity to select out individuals in the pathogen population that have resistance or reduced sensitivity to the fungicide.”

In 2008, Bradley’s laboratory began a project funded by the Illinois Soybean Association to develop a fungicide resistance monitoring program. Since then, his lab has been obtaining samples, conducting tests and monitoring isolates collected from Illinois.

“This year, we decided to cast our net a little farther, particularly in the South,” he says. “In Tennessee, FLS is a major soybean foliar disease. Dr. Melvin Newman of the University of Tennessee sent me samples from a field that had been sprayed twice with strobilurin fungicides but still continued to have high levels of FLS, which was an indication of potential fungicide resistance.”

Bradley’s team confirmed that the sensitivity of the Tennessee isolates was reduced as compared to the sensitivity of baseline isolates.

In petri dish tests conducted at the U of I, spores from isolates of Cercospora sojina germinated in the presence of high concentrations of azoxystrobin, pyraclostrobin, and trifloxystrobin, which are the strobilurin active ingredients found in Quadris, Headline, and Stratego.

“This proved we were dealing with isolates that have reduced sensitivity to strobilurin fungicides,” he said. “Currently, Tennessee is the only state in which we have documented isolates like these, but we are continuing to perform tests on isolates collected from fields in Illinois and other states.”

(Source: Jennifer Shike, College of Agricultural, Consumer and Environmental Sciences, University of Illinois)

Leave a Reply

Fungicides Stories
FungicidesSudden Death Syndrome, Brown Stem Rot Reported In Indiana Soybeans
September 3, 2014
Farmers and retailers should be watching for symptoms of these two diseases over the next few weeks as they are best managed through preventative methods. Read More
FungicidesResearchers Target Soybean Disease With Genetic Resistance Study
August 6, 2014
University of Illinois researchers will share new information on controlling sudden death syndrome through genetic resistance at this year's Agronomy Day. Read More
Soybean field
FungicidesValent Launches New Seed Protection Fungicide For Soybeans
July 16, 2014
The INTEGO SUITE System contains the first new, novel seed protection fungicide chemistry registered in 30 years by the EPA for protection against Pythium and Phytophthora. Read More
FungicidesNew Players May Make Pest Headlines In Corn, Soybean
April 1, 2014
The usual insects and diseases took a bit of a break in 2013, but other culprits surfaced — and could return. Read More
Top 100 Articles
CropLife 100Pinnacle Agriculture Acquires Minnesota Retailer
April 14, 2015
Pinnacle Agriculture Holdings, LLC, ranked No. 6 on the CropLife 100,  has successfully acquired Liebl Ag, LLC in Ada, MN.  Read More
CropLife 100CHS, Aurora Cooperative Complete Fertilizer Storage, Grain Shuttle Loading Facility
April 13, 2015
CHS Inc., the nation’s leading cooperative and ranked No. 5 on the CropLife 100, and Aurora Cooperative (ranked No. 21) Read More
CropLife 100GROWMARK Acquires Missouri Refined Fuels Terminal
April 2, 2015
Bloomington, IL-based GROWMARK and Magellan Pipeline Co. have entered into an agreement in which GROWMARK will acquire the refined fuels Read More
CropLife 100Wilbur-Ellis Acquires South Dakota Retailer
April 2, 2015
Wilbur-Ellis Co.’s Agribusiness Division, a recognized leader in precision agriculture technology and the distribution and marketing of plant protection, seed Read More
CropLife 100The McGregor Co. Closes Smith-Kem Acquisition
April 2, 2015
The McGregor Co. — ranked No. 16 on the CropLife 100 list of largest U.S. ag retailers — has completed Read More
CropLife 100BRANDT Commemorates National Ag Day
March 20, 2015
The Illinois agriculture community gathered at BRANDT global headquarters on March 18 to celebrate National Ag Day behind this year's theme Sustaining Future Generations. Read More
Latest News
Cornfield near Sioux City Iowa
HerbicidesU.S. Regulators May Start Testing Food For Glyphosate R…
April 21, 2015
U.S. regulators may start testing food products for residues of the world’s most widely used herbicide, EPA told Reuters’ Carey Read More
FungicidesBRANDT Adds Zonix Biofungicide To Portfolio
April 21, 2015
BRANDT has added Zonix biofungicide to its rapidly expanding line of organic and sustainable products. Zonix is a contact fungicide that Read More
ManagementMissouri Experts: Spring Planting Slow Start Won’…
April 20, 2015
In the first of the agronomy teleconferences with Extension specialists, University of Missouri Extension climatologist Pat Guinan said the slow Read More
Carl Casale of CHS
Industry NewsCooperative CHS Reports Net Income Of $471.5 Million Fo…
April 20, 2015
CHS Inc., the nation’s leading farmer-owned cooperative and a global energy, grains and foods company, has announced company net income Read More
Industry NewsCHS Insurance Names New Director Of Sales
April 17, 2015
Bryan Lewis has been named director of sales for CHS Insurance, the nation’s largest agribusiness insurance broker and full-service insurance Read More
Mature Waterhemp in Corn
HerbicidesGenetic Literacy Project: There’s No Such Thing A…
April 17, 2015
Read the latest “analysis” on GMOs from Consumer Reports and you’ll “learn” that glyphosate, the chemical developed by Monsanto (its Read More
HerbicidesNew Resistance To 2,4-D Discovered In Australia
April 17, 2015
In a world-first case of herbicide resistance, researchers have confirmed that sowthistle weed in the south east of South Australia Read More
ManagementNews From RTP Company Visits and Growers Buying Older S…
April 16, 2015
Paul Schrimpf and Eric Sfiligoj discuss recent trips to the Research Triangle Park area and market seed sales trends. Read More
soybean field
StewardshipNew ASABE Standard Establishes Framework For Sustainabl…
April 16, 2015
The American Society of Agricultural and Biological Engineers (ASABE) has initiated a project to develop a new standard to establish Read More
MicronutrientsSouthern States: An Inside Look At Our Tissue Sampling …
April 15, 2015
Remember learning about the food pyramid in school? The nutritional diagram recommends the proper amount of nutrients you need on Read More
Industry NewsArysta Adds New U.S. Fungicides Marketing Manager
April 15, 2015
Arysta LifeScience North America recently hired Deneen Sebastian as its Marketing Manager for U.S. Row Crops, Fungicides. Most recently, Sebastian Read More
FungicidesVerdesian Launches Phosphite-Based Cereal Fungicide
April 14, 2015
A new, phosphite-based fungicide designed for improved suppression of deoxynivalenol (DON) in wheat and barley infected by Fusarium head blight Read More
Mature Waterhemp in Corn
HerbicidesSURVEY: Close To 90% Of Growers Battle Weed Resistance
April 14, 2015
Herbicide resistance management continues to be a priority for corn and soybean growers, and they’re working together more effectively to Read More
CropLife 100Pinnacle Agriculture Acquires Minnesota Retailer
April 14, 2015
Pinnacle Agriculture Holdings, LLC, ranked No. 6 on the CropLife 100,  has successfully acquired Liebl Ag, LLC in Ada, MN.  Read More
StewardshipFMC Corp. Joins Sustainable Agriculture Alliance
April 14, 2015
FMC Corp. has joined Field to Market: The Alliance for Sustainable Agriculture, a multi-stakeholder initiative working to define, measure and Read More
Industry NewsArysta Adds Two To Goëmar Sales Team
April 14, 2015
Arysta LifeScience North America recently announced two new additions to the Goëmar sales team: Steve Kelly, Technical Service Manager – Read More
Valley Variable Rate Irrigation
Precision AgVariable Rate Irrigation Gains Followers
April 14, 2015
Irrigation systems have had the ability to apply different amounts of water throughout a field for decades, using timers that Read More
CropLife 100CHS, Aurora Cooperative Complete Fertilizer Storage, Gr…
April 13, 2015
CHS Inc., the nation’s leading cooperative and ranked No. 5 on the CropLife 100, and Aurora Cooperative (ranked No. 21) Read More