Fungicide Application Timing Trial
Sustainable Production
Crop protectionDiseaseField management
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Katherine Drake Stowe, US Soybean Research Collaborative
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

The purpose of this trial is to compare the top available fungicides on the market and determine the optimum application timing. It’s goal is to determine optimal fungicide selection and timing when managing foliar diseases such as frogeye leaf spot in a susceptible soybean variety in North Carolina.

Key Benefactors:
farmers, agronomists, extension agents

Information And Results
Project Deliverables

Final Project Results

FLS pressure varied from location to location. Three out of five locations had light-to-moderate FLS pressure, while the other two had minimal FLS pressure. At locations where FLS was light-moderate, the disease did not become prevalent until R3-5. At the final FLS rating, across all locations, there was no difference in FLS control among fungicide regimes. However, a relationship between increased FLS control and increased yield was observed. Fungicide application did not have a significant effect on moisture or test weight compared with the check. Compared with the UTC, fungicide application improved yield statistically in all but two treatments. Interestingly, when comparing yield among treatment timings of the same product, no statistical differences were observed. After statistical and economic analyses, the optimal fungicide regime was Quadris Top SB applied at R3, earning the grower $40.56per acre above the UTC. Runner-up was sequential application of Quadris Top SB applied at R3 and R5, earning the grower $40.12per acre above the UTC. In contrast, the highest negative loss-on-investment(-$33.50)resulted from application of Headline followed by Headline plus Tebustar. It is widely believed that application of fungicides containing strobilurin can increase green stem percentage at harvest. This study supports that such a relationship does exist, and that prolonged greenness can contribute to increased yield. Across all treatment timings, plots treated with Quadris Top SB were on average 5.9-7.4% greener at R7 than plots treated with any other fungicide. This observation corresponds with highest green stem ratings observed in 2015 occurring in plots treated with Quadris Top at R3. This study does not support the practice of multiple fungicide applications. Although substantial profit was observed following two applications of Quadris Top SB at R3 and R5, results show that this is not always the case and may be too risky of an investment.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.