Phytophthora sojae belongs to a group of organisms called oomycetes, also known as “water molds.” Seeds and seedlings can be infected and killed at any time after the seed has absorbed moisture. The fungus also infects plants later in the season following periods of heavy rain, causing stem rots or chronic root rot.

Luckily, there are ways to combat Phytophthora in soybeans. To maintain yield potential, follow these 4 tips for management:

1. Plant resistant varieties

• There are 2 different types of genetic resistance. Single-gene resistance is very specific to particular races, with the most common being Rps1a, Rps1c, Rps1k, Rps3a, Rps6, or a combination of these. Field tolerance levels will vary with all resistance genes and can be very important as we develop resistance to some genes.

2. Use quality seed treatment at planting

• Consult with a specialist such as your local NK® retailer to determine specific seed treatments to fit your fields’ needs. The higher usage of seed treatments has reduced the incidence of the damping off phase of Phytophthora. Keep in mind that seed treatments will offer little help later in the season against the stem and root rot phase of infection.

3. Improve soil drainage

• One of the most important control measures, well-drained fields dramatically reduce the incidence of the disease.

4. Rotate crops

• Crop rotation will not eliminate the disease since it can live in the soil for years. However, planting continuous soybeans will increase the inoculum levels in the soil, increasing the disease pressure.

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

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