Evaluation of Disease Management Systems in Soybean – White Mold - 2020
White mold (WM, also called Sclerotinia stem rot) is a substantial problem in the U.S. North Central soybean production region and in Canada. Caused by the fungus Sclerotinia sclerotiorum that overwinters in the soil, WM is often recognized by fluffy, white growth on soybean stems. WM development is favored by cool, cloudy, wet, and humid weather at first flowering. The disease is more problematic in soybeans in high-yield environments where high plant populations, narrow row spacing, and an early-closing canopy are commonly used.
The objective of this study was to evaluate a system-based approach for WM disease management supported by genetic resistance of germplasm and foliar fungicide.
Soybean products with varying levels of resistance to WM were evaluated under different fungicide management options.
Plots were randomized within the trial.
WM disease ratings were taken at the R6 growth stage.
50 trial locations from 2019 and 2020 were planted for this study, and the data shown below is the average of the 13 locations (26%) kept for this analysis because they had moderate to high white mold pressure.
White mold (WM, also called Sclerotinia stem rot) is a significant problem in the U.S. North Central soybean production region and in Canada. Caused by the fungus Sclerotinia sclerotiorum that overwinters in the soil, WM is often recognized by fluffy, white growth on soybean stems. WM development is favored by cool, cloudy, wet, and humid weather at first flowering. The disease is more problematic in soybeans in high-yield environments where high plant populations, narrow row spacing, and an early-closing canopy are commonly used.
The objective of this study was to evaluate a system-based approach for WM disease management supported by genetic resistance of germplasm and foliar fungicide.
Select soybean products with varying levels of resistance to WM were evaluated under different fungicide management options.
Fields with a history of WM were selected for this study.
Plots were planted in a split-plot design with fungicide treatment as the main plot and soybean product as the sub-plot.
Fungicide treatments included:
Soybean products used were classified as susceptible (S), moderately susceptible (MS), moderately resistant/moderately susceptible (MR/MS), moderately resistant (MR), or resistant (R) to WM.
Plots were randomized within the trial.
WM disease ratings were taken at the R6 growth stage.
Both fungicide treatments significantly contributed to WM disease suppression and an average yield advantage of 2 bu/acre over the unsprayed treatment.
For soybean products with below-average resistance to WM, the fungicide treatments resulted in a 4 bu/acre yield advantage compared to the unsprayed treatment.
Although not statistically significant, soybean products with enhanced resistance to WM provided an average yield advantage of 2 bu/acre over susceptible checks.
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