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Is White Mold Cause for Concern?

July 11, 2018

White mold is one of the most problematic diseases impacting soybean production due to it’s ability to significantly reduce seed yield and quality. White mold, caused by the fungal pathogen Sclerotinia sclerotiorum, has the ability to overwinter in the soil as sclerotia which germinate under dense, humid canopies during early reproductive growth stages. The spores of the fungus are then released and infect floral structures. The ability of the pathogen to infect plants later in the growing season is what makes it so difficult to control.

White mold is favored under cool, wet conditions when the plant canopies are dense during the early reproductive stages. While recent temperatures have been high, a wet June and a return to cooler temperatures could spell trouble for producers later this growing season. Fortunately, there are some options for producers to reduce incidence and severity of the disease. Increasing row spacing or reducing plant populations can improve air flow and reduce canopy cover, but this opens the door to increased weed pressure. Additionally, there are some fungicides on the market which claim to offer some level of control; however, timing and need of applications vary from year to year and market conditions make it even more difficult to justify additional inputs.

Due to the importance of this disease and the need to find cost-effective management strategies, University of Illinois Extension is in the preliminary stages of planning a research project to assess cultural and chemical control methods. Dr. Nathan Kleczewski, University of Illinois Extension Plant Pathologist, is looking for producers in Northern IL who would be willing to participate in an integrated management study in the coming years.

The study would look at various factors influencing white mold prevalence including: row spacing, seeding rates, planting dates, and chemical control methods. Importantly, this study hopes to establish a baseline which will guide future recommendations for producers to combat this problematic disease in a cost-effective manner. Interested parties may contact Phillip Alberti, University of Illinois Extension Crop Science Educator, at 815-235-4125 or to determine if they are suited for involvement in this project.

Source: University of Illinois