Researcher sorts through which practices make an impact on soybean yields and which don’t
You know that soybean sudden death syndrome (SDS) is a top yield robber. But when it comes to management strategies, there’s a lot of information out there.
In a recent presentation for the Plant Management Network, Daren Mueller, Ph.D., extension field crop pathologist at Iowa State University, used the latest research results to sort through the best management methods to help you protect your soybean yields from SDS.
Variety Selection
“There are many different management strategies that can be used for SDS, but the main one is variety selection,” he says. “Everything else complements or adds to selecting resistant varieties for SDS.”
Bottom Line: Variety selection is the No. 1 way to protect fields from SDS. Pick the most resistant varieties available for your area.
Fungicides
Mueller discussed the results of trials in Illinois, Indiana, Iowa, Michigan and Ontario that studied the effectiveness of fungicides on susceptible and resistant cultivars.
“Two of the products evaluated – ILeVO® and Luna Privilege in-furrow, which has the same active ingredient as ILeVO but is not commercially available – did reduce SDS when it was present,” he says. “No other foliar applications or products worked as well. This gives us hope that there are now seed treatments commercially available and products in the pipeline that may manage SDS.”
Bottom Line: Ask your retailer about seed treatments right for your farm.
Planting Date
Research suggests that early planting can increase the risk of SDS, but Mueller’s team wanted to find out if the risk continues to increase the earlier you plant.
The experiments revealed more root rot in the earlier planting, but foliar symptoms plateaued and there is a benefit to pushing up planting dates.
“We see a big difference in yields,” he says. “The earlier you plant, the higher the yields—regardless of the amount of disease present. Our recommendation would be to not delay planting to avoid SDS, because you’re also avoiding that yield bump you would experience with earlier planting.”
Bottom Line: Do not delay your planting schedule, but plant fields with a history of SDS last.
Glyphosate
In 2009, the European Journal of Agronomy published a paper that associated the use of glyphosate with weakening plant defenses and increasing a pathogen’s ability to infect plants. When SDS broke out in 2010, U.S. researchers looked for a connection.
“The results of the study found no significant differences between fields treated with glyphosate and those that were not,” Mueller says. “If SDS was not present and the field was sprayed with glyphosate, you did not magically get SDS. If SDS did show up in your fields, the use of glyphosate did not make SDS more severe.”
Bottom Line: Glyphosate has no impact on SDS under field conditions.
Tillage
Research conflicts on whether tillage is a beneficial practice for SDS. Some reports say no-till increases SDS, and others say no-till fields can have the least amount of SDS. So Mueller studied data for no-till fields planted to corn and soybeans; no-till corn and chisel-plow soybeans; and disc corn and chisel-plow soybeans from 2010 to 2014.
“We found that the amount of SDS in all three tillage regimes was very similar,” he says.
Bottom Line: The type of tillage strategy you use does not affect SDS severity.
Crop Rotation
Reports reveal higher levels of SDS in corn-soybean rotations due to the ability of the fungus to survive on corn kernels and residue. Iowa State researchers looked at changing up the corn-soybean rotation and testing long-term crop rotations to see the effects on SDS.
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