Soybean R3 Fungicide Trials

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

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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    Trial implementation

    • Farmer selected varieties and management.
    • Farmer selected fungicide used at R3. Provided as-applied map to document treatment locations.
    • Fields were scouted twice at the same 40 points in the field:
      • Once pre-spray (~R2).
      • Once post spray. Goal was 14 days after R3 application.
    • Drones were used to obtain field overview and high resolution (15 feet above canopy) imagery at both scouting dates.
    • Farmer provided yield map.

    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 (2018-2021)

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

    Soybean R3 Foliar Fungicide Trial locations

    2018, 2019, 2020 and 2021 fungicide trial locations

    There were 10 trials in 2018, 12 in 2019, 11 in 2020 and 11 in 2021.

    If you are interested in participating in this trial in 2022 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, 2020 and 2021 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.
    • Credible interval is the expected yield effect of R3 Fungicide based on these 43 trials farms (95% to 5% probability).

    This graph summarizes 43 strip trials including 495 strips.

    • >5 B/A response - 2 locations
    • >3 B/A response - 11 locations
    • >1 B/A response - 24 locations

    Key points

    • R3 fungicide increased yield.
    • Mean effect was 1.7 bushels per acre (95% credible interval is 1.2 to 2.1 bushels per acre) across 43 trials.

    Scouting summary

    Disease rating is on a scale of 0 to 100. Disease index is calculated as the incidence (%) times the severity (0 to 100). A score of 25 or greater is considered a high disease index. Greater than 50 is very high.

    scouting summary 18 19 20

    scouting summary 2021

    scouting disease summary

    Year-by-year yield summary

    Effect on yield

    Conclusions: This trial assesses effectiveness farmer management of R3 fungicide on soybean, not a specific product. Over four years and these farms there is a 50% chance that R3 fungicide increased yield more than 1.5 bu./A. Over four years and these farms there is a 98% chance that R3 fungicide increased yield more than 1.0 bu./A.

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    Location summary reports

    2018 (PDF)

    2019 (PDF)

    2020 (PDF)

    2021 (PDF)

This on-farm research was supported by the Missouri Soybean Merchandizing Council (award No. 18-415) and University of Missouri Extension. This on-farm research was only possible with the cooperation of Missouri Soybean farmers who volunteered to implement trials on their fields and the Regional MU Extension faculty that supported them.