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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Research Project #438887

Research Project: Tar Spot of Corn: Characterizing the Ecology and Epidemiology of an Understudied and High-Profile Disease

Location: Crop Production and Pest Control Research

Project Number: 5020-21220-014-016-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2020
End Date: Aug 31, 2024

1. Characterize the life cycles of Cercospora zeae-maydis, the cause of grey leaf spot, and Phyllachora maydis, causal agent of tar spot of corn, under natural epidemic conditions. 2. Develop a better understanding of environmental effects on C. zeae-maydis and P. maydis spread over time and space. 3. Characterize the spatio-temporal development of grey leaf spot and tar spot of corn on plant genotypes with various levels of resistance. 4. Develop adequate sampling methods for data collection required for phenotyping, surveillance, or disease prediction. 5. Test models for adequate characterization of corn leaf spot epidemics.

Isolates of the relevant pathogens will be obtained as needed, and field, greenhouse and laboratory analyses of fungal growth and development will be used to test epidemiological models of disease progression in the field. Life cycles will be determined by monitoring the pathogens using naturally infected or inoculated plants in the field. Disease spread will be monitored to understand environmental effects using visual, molecular and/or remote-sensing approaches. Corn lines with differing levels of resistance will be identified and monitored under field conditions to analyze spatio-temporal aspects of disease expansion and increase understanding of the factors influencing the development of epidemics. Monitoring methods will be refined and different sampling strategies will be tested to predict epidemic development. Methods of culturing the pathogens, inoculating and phenotyping plants for disease resistance will be developed and used to score plants for resistance. This will be particularly difficult for the tar spot pathogen, which so far cannot be grown in culture. The results will be used to test models about epidemic development for predicting the best approaches for controlling the diseases in the field.