Location: Sugarbeet and Bean ResearchTitle: First report of Stemphylium leaf spot of sugar beet caused by Stemphylium vesicarium
|METHENY, JACQUELINE - Michigan State University|
|JAYAWARDANA, MALINI - Michigan State University|
|WILBUR, JAIME - Michigan State University|
Submitted to: New Disease Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2022
Publication Date: 5/22/2022
Citation: Metheny, J., Jayawardana, M.A., Wilbur, J.F., Hanson, L.E. 2022. First report of Stemphylium leaf spot of sugar beet caused by Stemphylium vesicarium. New Disease Reports. 45(2). Article e12084. https://doi.org/10.1002/ndr2.12084.
Interpretive Summary: There are several foliar diseases that can affect the yield and quality of sugar beet. While sampling for a common leaf spot disease in 2019, samples were collected which showed symptoms not typical of the standard disease. When isolates were obtained, they were found to be a fungus, Stemphylium. A severe disease of beets, yellow leaf spot, has been reported in Europe caused by Stemphylium beticola, so testing was conducted to determine whether this might be present in Michigan. When genetic sequencing was used, the isolates were identified as a different species, Stemphylium vesicarium. This species has a wide host range and is known to occur in Michigan on some vegetable crops such as onion and asparagus. When the isolates were tested for their ability to cause disease on sugar beet, they caused leaf spot, but symptoms were generally less severe than those for yellow leaf spot. To our knowledge this is the first report of S. vesicarium from beet.
Technical Abstract: Sugar beet is subject to several foliar diseases that can impact yield and quality. In 2019, leaf spots were observed from two Michigan fields with atypical fungal growth. A Stemphylium species was obtained from these lesions. Because there have been reports from the Netherlands of a yellow leaf spot, a severe disease of beets, caused by Stemphylium beticola the Michigan isolates were identified to species and tested on beet. Three isolates were collected and all were identified as Stemphylium vesicarium. Genetic analysis was done using ITS and calmodulin that supported this identification. All three isolates were able to cause a mild leaf spot on two sugar beet germplasm and the same Stemphylium sp. was isolated from lesions, completing Koch’s postulates. Symptoms were generally milder than those for yellow leaf spot. Stemphylium vesicarium has a wide host range but to our knowledge this is the first report on sugar beet.