Soybean Variety Response to Delaro® 325 SC Fungicide

January 5, 2020


  • The objectives of this trial were to:
    • Evaluate if soybean products respond differently when given a fungicide application vs. no application.
    • Determine the impact of a fungicide application on soybean yield.


Location Gothenburg, NE Planting Date 5/16/19 Soil Type Hoard Silt Loam Harvest Date 10/16/19
Previous Crop Corn
Potential Yield
Tillage Type Strip tillage
Seeding Rate

  • The study was set up as a split plot with four replications where fungicide was the whole plot and soybean product was the subplot.
  • Twenty-four soybean products, ranging in maturity from 2.0 to 3.5, were evaluated.
  • Fungicide treatments included:
    • Untreated
    • Delaro® 325 SC fungicide applied at 10 fl oz/acre at the R3 growth stage 
    • Two Delaro® 325 SC fungicide applications applied at 10 fl oz/acre at the R1 and R3 growth stage
  • Plots were sprinkler irrigated and weeds were controlled chemically as needed.
  • Some soybean diseases (Septoria brown spot, Phomopsis pod and stem blight, and Anthracnose) were observed at low levels but no soybean diseases were prevalent at an economic threshold.


  • There was an interaction between soybean product and fungicide as detailed in Table 1. Some of the soybean products showed a large benefit to a Delaro® 325 SC fungicide application or two applications while other products showed no response.
    • A positive response to fungicide was observed 67% of the time with the single application of Delaro® 325 SC fungicide at the R3 growth stage and 79% of the time with the dual application at the R1 and R3 growth stage in a low disease pressure environment.
    • Ten of the soybean products had 4 bu/acre or more response to either the single or dual application as compared to the untreated soybean products.
    • The inconsistency in the yield response is similar to that observed in other studies when foliar diseases are below economic levels.1 Soybean response to a fungicide is often higher when disease pressure is high.


  • Soybean products tended to have different responses to an application or applications of Delaro® 325 SC fungicide compared to no fungicide applied.
  • This is research from only one site and one year, but it does provide some insight into how a soybean product may respond to a fungicide application on a broader scale or in different geographies, climate or an increase/decrease in fungicidal pressure.
  • Producers should consult with their local seed sales team to understand how their branded soybean product performed in this study and develop a plan on how to best manage it.


1 Giesler, L.J. 2008. Deciding when to apply soybean fungicides. University of Nebraska. Institute of
Agriculture and Natural Resources. https://cropwatch.unl.edu/deciding-when-apply-soybean-fungicides