By Jamie Martin
White mold is an important disease affecting soybean crops, especially as farmers aim for higher yields. The disease spreads easily under favorable conditions and can lead to serious losses if ignored.
Cool temperatures, wet weather, and thick plant growth create the ideal environment for white mold. Dense canopies increase humidity during flowering, while poorly drained areas and field barriers make conditions even more suitable for disease spread.
The fungus responsible for white mold enters fields through infected seeds, contaminated soil, and airborne spores. It produces sclerotia that can remain active in the soil for several years. When conditions become suitable, these structures release spores that infect nearby plants.
The disease begins with dead plant tissue, such as old flowers, and then spreads into healthy parts. Early signs include water-soaked lesions that quickly develop into white mold. Affected plants wilt, collapse, and die, allowing the infection to spread across the field.
Effective control requires combining multiple management strategies. Farmers should choose tolerant soybean varieties and consider crop maturity, as longer flowering periods increase infection risk.
Crop rotation with non-host crops, especially small grains, helps reduce disease levels. Managing weeds is also critical, as many weed species can carry the infection. No-till farming practices help limit disease development by keeping fungal structures exposed on the soil surface.
Fungicides are useful for controlling white mold in high-risk conditions. They should be applied before symptoms appear, typically during early flowering stages. Applications made up to the R3 stage can still offer some benefit.
Since fungicide activity lasts for a limited time, farmers may need to apply a second treatment 10 to 14 days after the first. This ensures ongoing protection during the flowering period.
“Many studies year over year say the same thing, two different fungicides applications is the best way to prevent white mold from affecting your yield,” said Eric Rice, Pioneer field agronomist. “I’d apply my fungicide any time I start seeing flowers. I would follow that up about 10 to 14 days later, just systematically, with the second application, and that is the best way to do it to get a full season of protection against white mold.”
Agronomists recommend consistent monitoring and timely application to balance yield goals and disease prevention. Combining cultural practices with chemical control remains the best strategy for managing white mold in soybeans.
Photo Credit: istock-sandramatic
Categories: National