Research Outlines Spacing, Seeding, and Fungicide Strategies
Research conducted by North Dakota State University, White mold remains a major disease concern for soybean growers, particularly during seasons with cool temperatures and frequent moisture. Weather conditions that favor extended canopy moisture increase the likelihood of disease development, not only in soybeans but also in crops such as dry beans and sunflowers.
Long-term research offers practical guidance to help producers manage disease risk while maintaining yield and grain quality.
Planting row spacing is one of the most effective tools for reducing white mold pressure. Wider row spacing allows more air movement and light penetration, which lowers humidity within the crop canopy.
However, research showed that wide rows only provide a yield advantage when disease pressure is extremely high. In most situations, intermediate row spacing of approximately 21 to 22.5 inches delivers the best balance between disease suppression and yield potential.
Seeding rates also play a critical role in disease management. Higher plant populations lead to denser canopies that favor white mold development. Research indicated that reducing seeding rates can significantly lower disease levels.
Planting roughly 100,000 viable seeds per acre is most effective when white mold symptoms appear at least 15 percent of the canopy later in the growing season.
Soybean variety selection further influences disease risk. Varieties with longer maturity periods tend to face greater exposure to favorable white mold conditions.
Selecting varieties with appropriate maturity groups and improved disease tolerance can reduce overall risk. Fields planted with longer-maturing varieties are more likely to benefit from fungicide applications.
Proper fungicide timing is essential for effective disease control. When environmental conditions favor white mold during early flowering, a single fungicide application is most effective when nearly all plants reach the R2 growth stage or when the canopy begins to close.
In fields with higher disease risk, two fungicide applications provide stronger protection. The first spray should be applied early in bloom, followed by a second application timed according to the variety’s maturity.
Spray coverage also affects fungicide performance. Smaller droplets provide better coverage when the canopy is open, while medium to coarse droplets improve penetration as the canopy closes. Canopy closure can be assessed visually or with mobile applications that assist with spray decisions.
By applying these research-backed strategies, soybean producers can reduce white mold losses, protect grain quality, and improve long-term farm profitability through smarter planting and disease management decisions.
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