Common soybean diseases of the leaves, root, stem and pod can threaten crop production throughout the growing season. Typically, fungal diseases can occur as early-season foliar disease, but continue after flowering. Foliar disease reduces photosynthesis, causes leaf drop and affects pod set. Common root, stem and pod diseases can cause pod and seed decay, leading to significant yield loss.
Soybean fungal diseases include: anthracnose; Septoria leaf spot (brown spot); brown stem rot; charcoal rot; damping-off; powdery mildew; frogeye leaf spot; Fusarium root rot; Phytophthora root and stem rot; Cercospora blight, leaf spot and purple seed stain; Rhizoctonia root rot; Sclerotinia stem rot (white mold); and the fungus leading to sudden death syndrome (SDS).
Best management practices
Best management practices help minimize the potential for fungicide resistance and include cultural practices, planting disease-tolerant hybrids and applying fungicides with multiple modes of action.
Because several disease organisms survive in infected residue from crop to crop, there are several cultural practices that can help break this cycle and diminish disease pressure. For example, crop rotation allows surface crop residue to break down, reducing fungal inoculum populations. Incorporating crop residue into the soil can further reduce the disease population the following season. Good weed control removes disease hosts, too.
Plant disease-tolerant seed
Before planting, a field’s specific disease history should be taken into account and then matched with a resistant soybean variety. For example disease-tolerant seed traits, specific to soybean growers, can be found in Credenz® soybean seed. Credenz can provide built-in protection against stem canker, frogeye leaf spot, Phytophthora root rot and SDS, plus multiple herbicide-tolerant traits and nematode control. When followed by timely fungicide applications, Credenz soybeans are best protected against yield-robbing diseases.
A fungicide seed treatment can provide a healthy start for seedlings. Multiple fungal pests can impact soybean seeds and seedlings immediately after planting, and EverGol® Energy SB can protect against pests causing the most damage such as Rhizoctonia solani, Fusarium spp and Pythium spp. In cool and damp conditions, ILeVO® soybean seed treatment from Bayer protects against the fungus causing SDS in soybeans. ILeVO is an important risk management tool for growers to protect against SDS. Additionally, since SDS can occur as a disease complex with soybean cyst nematode (SCN), planting soybean seed treated with Poncho/VOTiVO® will help protect seedlings against nematodes as well as certain insects during the critical early development stage.
Foliar fungicide applications
Applying foliar fungicides is another important step to prevent or manage many diseases. For example, Stratego® YLD fungicide controls a broad spectrum of diseases. It combines the latest in triazole technology, complemented with strobilurin chemistry. Offering two modes of action, it provides both preventive and curative benefits and systemic movement to provide broad-spectrum, long-lasting disease control and higher yield potential.
Timing of fungicide application
In soybeans, the ideal time to first apply Stratego YLD is prior to disease development, or at beginning pod (R3), with applications repeated as necessary. Disease-susceptible cultivars and seed soybeans are most likely to benefit from a Stratego YLD application. For cost efficiency, fungicides can be tankmixed with insecticides and applied in the same trip across the field.
Fungicide timing and yield bump
With Stratego YLD, yield increases over untreated soybeans have been consistently demonstrated. Soybeans treated with Stratego YLD averaged a yield bump of 2.9 to 3.3 bushels when compared to untreated soybeans in trials over a four-year period. In fact, soybeans treated with Stratego YLD at early flowering, around growth stage R3, averaged a 3.25-bushel yield increase.
For more information on soybean disease control options from Bayer, contact your local Crop Science representative or visit www.bayercropscience.us/crops/soybean.
Before purchasing seed, selecting a seed treatment or applying any fungicide, please read the entire label for the best possible results and to confirm that the product is effective on the disease you need to control. Every product is not suitable for every situation, and correct application technique will ensure the best results.