Corn tar spot is a leaf disease caused by the fungus Phyllachora maydis. It produces black spots on leaves, and can cause significant yield loss for corn, the most widely grown crop in Minnesota. Yield loss can exceed 40%. It was first detected in the United States in 2015 in Illinois and Indiana, and has since spread to multiple states in the Midwest, including southeastern Minnesota where it has been confirmed in 12 counties. Currently, there is limited information about the distribution, biology, and management of corn tar spot.
- What is the distribution of corn tar spot, and how established is it?
- How do we detect corn tar spot?
- How will corn tar spot respond to future weather conditions?
- What are our management options for corn tar spot, and how effective are they?
This project will document distribution of corn tar spot over time. It will also clarify the host range of the tar spot pathogen to determine if common plant species can harbor it. Methods to detect tar spot will be validated and developed as needed.
Lastly, pilot studies will be conducted to evaluate fungicides and corn hybrids to manage tar spot in Minnesota environments.
- Tar Spot of Corn: A Diagnostic and Methods Guide (Plant Health Progress, 2022)
News and media
- Beware: Mysterious fungus pathogens are among us: Diseases impact corn and soybean production in Minnesota (College of Food, Agricultural and Natural Resources News, 2023)
- University of Minnesota Extension urges growers to scout for tar spot in corn (Southern Minn Faribault News, 2022)
- Scout for tar spot of corn (Minnesota Crop News, UMN Extension, 2022)
- Tracking Tar Spot: Protecting Minnesota's corn (MITPPC)