Bacterial leaf streak (BLS) in corn was recently identified in Iowa. Bacterial leaf streak is a disease caused by Xanthomonas vasicola pv. vasculorum. The disease has been found on field corn, seed corn, popcorn, and sweet corn. Iowa State University Extension and Outreach has been working with the USDA, Iowa Department of Agriculture and Land Stewardship (IDALS), the Iowa Crop Improvement Association (ICIA) and surveying several counties in the state. To date, Iowa State University has confirmed the disease in six counties in north central and northeast Iowa (Fig. 1). (Click image for larger view)
Figure 1. Counties from which the ISU Plant Disease and Insect Clinic has received samples that are positive for bacterial leaf streak. These counties include: Hancock, Webster, Grundy, Marshall, Tama, and Buchanan.
Symptoms
- Long, narrow lesions that are less than 1 inch to several inches long
- Lesions are tan, brown, or orange and occur between the veins of the corn leaves (Fig. 2a)
- Lesions can also occur close to midrib or across the leaf blade
- Bacterial leaf streak lesions look similar to gray leaf spot (GLS) except they have wavy margins while GLS lesions have straight sides that look more rectangular (Fig. 3a)
- If backlit, bacterial leaf streak has long, yellow halos that extend from each lesion (Fig. 2b), unlike GLS lesions (Fig. 3b)
(a) 
(b)
Figure 2. Characteristic symptoms of bacterial leaf streak of corn (a). Note the long yellow halos extending from either end of the lesion when the leaf is backlit (b).
(Click images for a larger view)
(a) 
(b)
Figure 3. Characteristic symptoms of gray leaf spot of corn (a). Backlit gray leaf spot lesions (b).
(Click images for a larger view)
Submit a sample
If you suspect bacterial leaf streak in your fields, please submit a sample to the Iowa State University Plant and Insect Diagnostic Clinic (PIDC). The sample should consist of 6-10 leaves that vary in disease severity (few to many lesions). Wrap the leaves in a dry paper towel and place them in an envelope. If you are able, please overnight ship or drive the sample to the clinic. Standard fees apply for diagnosis based on symptomology and bacterial streaming. Confirmation via PCR is an additional $10.
More information may be found at the following websites:
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on August 26, 2016. The information contained within may not be the most current and accurate depending on when it is accessed.
Alison Robertson Professor of Plant Pathology and Microbiology
Dr. Alison Robertson is a professor of plant pathology and microbiology. She provides extension education on the diagnosis and management of corn and soybean diseases. Her research interests include Pythium seedling disease of corn and soybean and Goss's wilt. Dr. Robertson received her bach...