Nebraska battles diverse soybean diseases

By Scout Nelson

Nebraska's diverse planting conditions are currently promoting a variety of seedling diseases in soybeans, each favoring different environmental triggers. From water molds in cool, wet conditions to fungal pathogens in drier soils, the state’s farmers are facing significant challenges.

Common during cool and wet springs, water molds such as Pythium and Phytophthora thrive, affecting seedlings by inhibiting moisture movement, leading to damping off. This issue can manifest either before or after emergence, visibly impacting plant rows.

On the drier side, fields are seeing an increase in diseases like Fusarium and Rhizoctonia, more prevalent in sandy or well-drained loamy soils, which lead to root rot and stunted growth.

Pythium is notably problematic in wet conditions, with cooler soil temperatures intensifying the stress on seedlings. Infected plants may show seed decay, pre-emergent seedling rot, and damping off once emerged, with roots that easily separate from the core.

Rhizoctonia Root Rot, favored by drier conditions, typically presents as reddish-brown lesions on the lower stem, near the soil.

Fusarium Root Rot manifests through stunted growth and discoloration on the roots, often in the lower part of the root system in similar dry conditions.

Phytophthora becomes more common as soils warm and saturate, often in fields with a history of the disease. It causes seed decay, seedling rot, and damping off, with notable darkening at the base of the stem.

Management Strategies involve improving field drainage, optimizing planting times to avoid extreme conditions, and using seed treatments.

Fungicides, applied at planting or near the seed furrow, offer additional protection, though their effectiveness can vary with environmental conditions and the specific pathogen present.

For best results, farmers are encouraged to plant high-quality seeds at appropriate depths and ensure soil conditions are favorable for rapid germination and emergence, thereby reducing the incidence of seedling diseases. This comprehensive approach helps reduce the impact of these diverse pathogens on Nebraska’s soybean crops.

Photo Credit -istock-sandramatic