The Interaction of Sulfur and Scab Disease

Nutrients in the soil are essential to crop growth functions, but they often fulfill other vital roles as well. For example, sulfur (S) can serve to inhibit the spread of powdery scab disease in potatoes1.

Powdery scab is a problem in all potato-growing regions. Causing ugly blemishes on tuber surfaces, a scab infestation can severely affect the quality and marketable yield of a crop2. The disease threat is worse with intense irrigation and poorly drained soil (which helps to support the fungus) and less frequent crop rotation – although the scab pathogen has been known to survive in soils for ten years3.

One way to help minimize powdery scab is simply to maintain adequate levels of sulfur in the potato field. Extensive research has shown that sulfur directly and indirectly affects activity of the disease. First, sulfur changes the biology of the soil environment, which acts to stimulate microbial competition and greatly reduce the virulence of the scab pathogen itself4.

Secondly, fertilizing with sulfur helps to increase a potato plant’s own natural disease resistance. Sulfur is also known to be effective against fungi such as late blight and stem canker disease5.

Additionally, there are several issues regarding sulfur that today’s growers need to keep in mind:

  • Sulfur deficiencies are becoming more common
  • Air quality standards reduce sulfur deposition from the air
  • Increased crop yields remove more S from the soil
  • Elemental sulfur must oxidize and convert into sulfate sulfur to be available to plants. That oxidization can take too much time to make the sulfur available during the current growing season

Replenishing sulfur and assuring proper levels should be part of your basic fertility program. Protassium+® premium sulfate of potash (SOP) is an excellent form of potassium (K), containing 17% sulfur in sulfate form, making it immediately available for plant uptake versus elemental sulfur.

For more information on the benefits of sulfur for your potatoes or how Protassium+ SOP better serves your growing success, contact us or call 1-855-308-3334.

1,4 The Roles of Sulfur in Nutrient – Disease Interactions; Purdue University Department of Botany and Plant Pathology

2,3 Developing Integrated Management Strategies for Powdery Scab on Potato Crops; Oregon State University

5 The Role of Nitrogen and Sulfur on Plant Disease Incidence and Resistance; Purdue University Department of Botany and Plant Pathology, 2005$FILE/Palestra%20Don%20Huber.pdf