Sudden Death Syndrome (SDS) can infect soybean roots early in the season. However, it is not until after flowering that above-ground symptoms will start to appear in your field. To reduce potential yield loss, be proactive about your seed selection and have a disease management plan in place.

What causes SDS?

SDS can infect soybeans after germination when the root systems are vulnerable. The risk of SDS infection is greatest when there is significant moisture early in the growing season followed by mid-summer rains saturating the soil. Poorly drained or compacted soils are also favorable for this disease. The presence of soybean cyst nematode (SCN) can make the disease worse – opening the roots up to infection and weakening the plants’ defenses to disease as a result of feeding.

Foliar symptoms:

• First, the outermost leaves in the canopy are affected, with chlorotic spots between veins on the leaves
• These yellow spots coalesce to form chlorotic yellow, brown interveinal leaf scorching
• A common diagnostic symptom of SDS is that the mostly necrotic leaflet detaches, leaving the petioles attached to the plant canopy

More symptoms and signs:

• Growth of the fungus expands with the root tissue and can grow into the lower portion of the plant stem
• A symptom of the SDS-infected soybean stem is that the inner stem pith remains green/white, while the outside of the pith area will appear a gray-brown color
• Infected soybean plants are susceptible to flower and pod abortions because of leaf/canopy reductions and further deterioration of the root and stem tissues restricting water uptake and nutrient supply/movement
• Another symptom that may be seen when there is adequate soil moisture is cobalt blue growths on the outer root surface

Management Tips

Unfortunately, there are no in-season management tools for either SDS or SCN because the fungal infection is restricted to root systems. Therefore, the key to preserving yields is to start strong and protect young root systems. Select elite NK^® soybeans with excellent SDS tolerance, use seed treatments to help manage SCN populations and provide protection from soil fungal pathogens, and treat your soils well by improving drainage and avoiding severe compaction.

If you suspect SDS is impacting your fields, speak with your local NK retailer for management recommendations.

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