Scouting for tar spot. Credit: Domini Brown
Background
Tar spot of corn is an emerging plant disease in the United States caused by the invasive pathogen, Phyllachora maydis. It has caused significant yield loss across the country, estimated at 230 million bushels in 2021.
The pathogen was first found in Minnesota in 2019 and the distribution has since increased to 23 counties. Its establishment in Minnesota is not well understood. Management options to mitigate the loss of corn production are currently limited.
This project team seeks to build on previous research, and generate information about tar spot of corn to better enable risk assessment, mitigation, and management. They will build on previous work in which they collected and studied other Phyllachora species found on different plants in the state. Specifically, researchers will investigate the distribution, host range, ideal growing conditions, and determine key factors that influence disease development of P. maydis in Minnesota.
Research questions
- What is the distribution, host range, and dispersal of P. maydis in Minnesota?
- What are the conditions and pathogen characteristics that favor development of P. maydis in Minnesota?
- What is the best inoculation method to enable research in field and greenhouse studies?
- What key factors influence disease development and efficacy of management practices?
Practical implications
The results of this work will provide the information needed to understand and effectively manage P. maydis, filling the large gaps of information that exist about this disease. By understanding key variables particular to Minnesota, land managers will be able to more accurately assess risk and develop durable disease management practices for tar spot of corn.
Outcomes
This project began in January 2023 and is in progress for the next 3 years. Please check back at a later time for updates.
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Publications
- Foliar inoculation of Phyllachora maydis into corn induces infection and local spread in field environments (Plant Disease, 2024); author's manuscript available to read for free
Outreach
- Crop Pest Management Short Course, 2024
- UMN Extension Research Updates (Rochester, Waseca, Lamberton, Wilmar, Crookston), 2025
- Meeting with crop consultants in Morton, MN, 2025
- South Dakota State University regional webinar, 2025
- Meeting with Corteva plant pathologists, 2025
- Strategic Farming webinar, UMN Extension, 2025
- Extension program meetings across Minnesota, 2025
News and media
- Bursting the fungal menace of corn tar spot wide open - MITPPC
- Tar spot update: Experts answer questions after tough year - Indiana Prairie Farmer
- José Solórzano profile - Dept. of Plant Pathology
- UMN scientists make breakthrough in tar spot pathogen research - MN Daily
- Breakthrough on tar spot pathogen enables field research - UMN News
- Studying tar spot just got easier - FarmProgress
- Identifying the host range of the fungus Phyllachora maydis, the corn tar spot pathogen - Minnesota Mycological Society
- Uncovering clues to corn tar spot, a complex and cold-hardy fungus - MITPPC