White mold poses a recurring threat to soybean fields in various regions, including Minnesota. While specific conditions can favor its development, outbreaks have been observed even when all the typical requirements are not met. As temperatures cool and rainfall increases, the risk of white mold in soybean fields escalates.
White mold thrives during soybean flowering, particularly when the soil remains moist for extended periods and both stems and leaves are consistently wet, coupled with temperatures below 68°F. Outbreaks have occurred under different conditions, challenging our understanding of its behavior.
Monitoring White Mold Risk:
To assess white mold risk, consider the field's history with the disease, crop density, growth stage, and recent and forecasted weather conditions. The University of Wisconsin has developed a useful risk assessment tool called Sporecaster, which can aid in determining the likelihood of white mold development. Fields with a history of manure application and the presence of certain weed species may be at higher risk.
Preventive Measures:
Several proactive measures can help reduce the risk of white mold. Planting partially resistant soybean varieties, adjusting plant populations, and adopting wider row spacing can all contribute to minimizing the disease's severity. However, it is important to note that white mold can persist in the soil for years, rendering crop rotation ineffective in completely eradicating it.
During the early flowering stages (R1/R2), fungicides can effectively control white mold if the risk is deemed high. Timely application is crucial for optimal results. In fields where white mold levels are typically high, two fungicide applications (at R1/R2 and R3 stages) have shown to protect yield and deliver profitable outcomes.
In fields with less severe white mold issues, a single application at the R1/R2 stage is usually sufficient for profitability.
For more in-depth information on white mold and its management, the following resources are recommended:
U of M Extension's Soybean White Mold webpage
White mold remains a persistent challenge for soybean farmers, often causing significant yield losses. By implementing preventative measures, utilizing risk assessment tools, and employing timely fungicide applications, farmers can enhance their ability to manage white mold effectively. Continuous research and collaboration among experts and farmers are essential in the ongoing fight against this damaging disease.
Photo Credit: gettyimages-gilaxia
Categories: Minnesota, Crops, Soybeans