Downy mildew is beginning to show up in many sunflower fields across North Dakota and South Dakota, according to a report from North Dakota State University. With the ability to wipe out large areas and significantly decrease yield, downy mildew is one of the most devastating diseases that can strike sunflower fields.
Symptoms of infected sunflowers include stunting of the plant, chlorosis along the veins on the upper side of the leaves, and a white cottony appearance on the underside of the leaves. Downy mildew generally favors cool temperatures and high relative humidity, and later-planted sunflowers are more susceptible to infection. With the volume of rain the states received in May and June, the large amount of downy mildew is not surprising.
Unfortunately, there currently are no management tools that are effective once downy mildew infection occurs. To protect sunflowers against the disease from the start, plant a downy mildew-tolerant sunflower hybrid and consider a fungicide seed treatment for added protection in less-tolerant hybrids and areas most at risk for the disease. A seed treatment like CruiserMaxx® Sunflower plus Bion® insecticide/fungicide provides superior insect and disease protection, increased germination and emergence, improved stand establishment, and enhanced downy mildew protection.
By monitoring and proactively implementing the right cultural and chemical management practices, you can manage the disease and preserve yield.
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Reporting from Bismarck, ND