Specific outputs include biweekly ratings for disease incidence and severity for each of the treatments at each of the 3 locations for the fungicide trials and disease demonstration plots beginning in July. Once disease severity starts to build, we will post these results in the Clemson University Soybean Rust Newsletter so that growers will have a reference point for their area of the state to make a “spray/don’t spray” decision on their soybeans.

Soybean foliar fungal disease evaluation workshops will be held in September at each of the 3 locations for growers, county agents, and consultants. Follow up workshops will be held at each location prior to defoliation for everyone to see the efficacy of each fungicide in controlling the various fungal diseases.

Data on fungicidal effects on disease severity and incidence, defoliation, and yield will be summarized and presented at the South Carolina Corn/Soybean Meeting in December. This data will also be summarized into a bulletin and web sites on the Clemson University Agronomic Team Web site.

Quarterly reports and a final report will be submitted on time using the National Soybean Research Database platform, as defined in the RFP.

Updated January 19, 2022:

View uploaded report 4

Plots were successfully taken to harvest at both the Edisto and Piedmont Research and Education Centers. Eleven fungicide regimes and a nontreated check were applied at the Edisto REC and 6 fungicide regimes and a nontreated check were applied at the Piedmont REC. All plots were harvested using a modified small plot combine.

The 2021 growing season was an excellent year for soybean production, especially in the Savannah Valley. Very few foliar diseases were detected at either the Edisto or Piedmont REC locations. The most significant fungal disease observed was soybean rust. However, even it appeared too late at both locations to have major impacts on yield. Rust was first detected on September 20th at the Edisto REC. It was only 1 pustule on 1 leaf. By October 13th it was present at a mean severity of 31% across all of the leaves in the Check plots. On October 18th it was present on more than 53% of the leaves. Several fungicide regimes including Tebuzol 3.6F, Approach Prima, Revytek and Delaro Complete 458 SC provided very good control of soybean rust. Yields at the Edisto REC location were excellent exceeding 60 bu/acre in most plots (Table 3). Rust seemed to have minimal effect on yield. Yield in the nontreated check regime was 66.4 bushels. Only Topguard EQ (70.5) and Stratego YLD (69.6) appeared to out yield the nontreated check.

At the Piedmont REC Rust was present on approximately 10% of the leaves of all treatment regimes by October 6 (Table 4. On October 25th 100% of the leaves in the check plots had rust present on them with approximately 64% of the leaf area affected. All fungicide treatments reduced the incidence of rust on October 25th with Approach Prima, Revytek, and Folicur providing the highest levels of reduction in incidence. All fungicide regimes reduced rust severity on October 25th by more than 50%. Yields at the Piedmont REC were lower than at the Edisto REC with a range from 24.3 to 33.2 bushels per acre. Yield of the check was 32.1 bu/acre; no treatment appeared to significantly increase yields.

Both tests show that application of a fungicide does not automatically result in an increase in yields. Both tests had low levels of diseases such as Frogeye leaf spot, Cercospora leaf spot, and Target spot making application of a fungicide to control yield losses unneeded. In both fields levels of soybean rust were high immediately prior to defoliation. However, this disease pressure was too late in the year to cause significant yield losses.