Soybean R3 Fungicide Trials

Key question: Are fungicides applied at R3 to soybean effective at increasing yield and reducing foliar disease?

Treatments: Strips with fungicide applied at R3 vs. strips with no fungicide application.
*Farmer’s choice of product used.

Fungicide trials information and results

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    Layout of the trial

    Each fungicide trial is custom designed to work within the individual farmer’s designated field using their own equipment to plant, spray, and harvest the treatment strips in their field.

    The farmer chooses the variety of soybean to be planted, the fungicide product and all other management decisions.

    Each field is laid out with a minimum of five fungicide sprayed strips and five strips not sprayed with fungicide. The width of the strips is based on the size of your spray equipment.

    In the example below, the green strips were sprayed with fungicide at R3. The blue points are where the field was scouted for foliar disease.

    Fungicide trial map layout

    To document differences in disease between the treatment strips, scouting for foliar diseases was performed at several locations within each treatment strip prior to and approximately two weeks following the fungicide application at the R3 stage. In addition, aerial imagery was taken at each of the scouting points to visually document the differences.

    Scout images

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    Results summary (2018-2020)

    Get the full three-year yield summary report (PDF)

    Soybean R3 Foliar Fungicide Trial locations

    2018, 2019 and 2020 fungicide trial locations

    There were 10 trials in 2018, 12 in 2019 and 11 in 2020.

    Key conclusion: Across these 33 trials, an R3 fungicide application increased yield. The median response was 1.5 bushels per acre and a 90% probability that the response across all locations was 1.2 to 2.2 bushels per acre.

    If you are interested in participating in this trial in 2021 or have questions/comments, please contact your local Extension Agronomist or Agricultural Engineer.

    R3 Fungicide for Soybean: Location details

    Note: First two numbers in location ID is the year.

    2018, 2019, and 2020 fungicide trial location details

    R3 fungicide application detail

    application detail

    R3 Fungicide for Soybean: Effect on yield

    Effect on yield

    How to interpret graph:

    • Green diamonds are the mean effect of fungicide treatment for each location; diamonds right of the center line indicate the mean effect at that location was positive.
    • Black (no R3 fungicide) and gold (R3 fungicide) symbols are strip yields for each location, as the difference from the location mean. Points to the right of the green triangle are strips with yield greater than average. Points to the left of the green triangle are strips with yield less than average. A location with most gold symbols to the right and most black symbols to the left of the green triangle likely benefited from fungicide.
    • Credible interval is the expected yield effect of R3 Fungicide based on these 33 trials farms (95% to 5% probability). Mean effect was 1.7 bushels per acre. 95% credible interval is 1.2 to 2.2 bushels per acre.

    Scouting summary

    Disease rating is on a scale of 0 to 100. A score of 25 or greater is considered a high disease index. Greater than 50 is very high.

    scouting summary

    scouting disease summary

    Year-by-year yield summary

    Effect on yield

    Conclusions: Yield benefits were greatest in 2020. Across three years the median benefit was over 1.7 bushels per acre. There is a 90% probability the benefit was between 1.2 and 2.2 bushels per acre.

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    Summary reports

    2018 locations 2019 locations
    1. Ralls County (PDF) 1. Barton County (PDF)
    2. Barton County (PDF) 3. Greene County (PDF)
    3. Polk County (PDF) 4. Holt County (PDF)
    4. St. Clair County 5. Scott County (PDF)
    5. Nodaway County (PDF) 6. Lincoln County (PDF)
    6. Warren County (PDF) 9. St. Clair County (PDF)
    7. Scott County (PDF) 10. Buchanan County (PDF)
    8. Perry County 11. Perry County (PDF)
    9. Atchison County (PDF) 13. Mississippi County (PDF)
    10. Marion County (PDF) 14. Ralls County (PDF)
    11. Lincoln County (PDF)