By Blake Jackson
Fungicides can play a crucial role in an integrated pest management plan, but they do not always guarantee a positive return on investment for soybean producers, according to University of Missouri strip trial research.
Missouri farmers apply fungicides to approximately 65% of soybean acres, says MU Extension state plant pathologist Mandy Bish. However, only 10% of fields are scouted before fungicides are applied to determine their necessity. In 2004, before soybean rust reached the United States, fungicides were used on just 1% of Missouri soybean fields.
MU Extension strip trials conducted on soybean fields across the state have demonstrated that while many fungicide applications result in yield increases, those increases do not always offset the cost of a $40 per acre application.
In 66 strip trials, only 21% showed yield increases greater than or equal to 3.3 bushels per acre following an R3 fungicide application, Bish notes. Additionally, in 23% of trials, yields were lower after fungicide applications.
Research from nine Midwestern states and Canada mirrors these findings, showing a 2.7% yield increase in fungicide-treated soybeans compared to untreated soybeans.
“In a year where we are looking to cut back on inputs, fungicide applications to soybean may be one practice that farmers want to reevaluate,” Bish states. “We do not often see foliar disease outbreaks in Missouri soybean fields to levels that warrant a fungicide application.”
In addition to the financial implications, excessive use of fungicides carries the risk of fungi developing resistance over time. “We know that we have fungicide resistance occurring with the fungus that causes frogeye leaf spot disease in Missouri soybeans,” Bish adds.
The Crop Protection Network highlights that fungicide applications can be effective during specific times. Diseases such as soybean rust, white mold, target spot, and severe outbreaks of frogeye leaf spot and septoria brown spot may require fungicide treatment. The timing of these applications depends on the disease present.
Genetics and best management practices continue to be the most effective methods for controlling most foliar diseases in Missouri soybeans, according to Bish.
Research for MU Extension Strip Trials is funded by the Missouri Soybean Merchandising Council, Missouri Corn Merchandising Council, Missouri Fertilizer Control Board, North Central Sustainable Agriculture Research and Education partnerships, and MU Extension.
Photo Credit: istock-sandramatic
Categories: Missouri, Crops, Soybeans