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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Crop Bioprotection Research » Research » Research Project #444217

Research Project: Efficacy of Commercial Biocontrol Saprophytes in Reducing Viability of Tar Spot Pathogen in Overwintered Cornfield Debris

Location: Crop Bioprotection Research

Project Number: 5010-22410-024-004-T
Project Type: Trust Fund Cooperative Agreement

Start Date: Apr 1, 2023
End Date: Mar 31, 2025

Objective 1: Determine survival of corn tar spot pathogen on overwintered corn leaves with and without fall treatment of a commercial saprophyte. Objective 2: Characterize the microbiome of overwintered tar spot-infected corn leaves with and without fall treatment of a commercial saprophyte.

As an initial proof of this control strategy, corn leaf sections infected with tar spot were treated with a commercial biocontrol organism found to be effective against tar spot and were set up in a field plot study in November of 2022. These leaf sections will be evaluated in April of 2023 for tar spot viability, as well as for the presence and viability of other foliar pathogens of corn such as gray leaf spot and common ear rot fungi. Controls will consist of tar spot infected corn leaves that will not be treated with biocontrol organisms. The research will be expanded to include other commercial products of the same type labeled for corn. Corn leaves infected with tar spot will be collected from research plots at our laboratory in Peoria, or from existing grower cooperators. Corn leaf sections infected with tar spot will be treated with relevant levels of different commercial biocontrol organisms as described above in late Fall, 2023 (approximately November 1), and evaluated for presence and viability of tar spot and other foliar pathogens of corn prior to local planting time (approximately early April 2024). To evaluate the survival of tar spot and other leaf pathogens, leaf pieces will be soaked in water as necessary to rehydrate, and the infected leaf areas will be examined for growth of respective fungi. Representative fungal materials will be picked off leaves and grown on media in Petri dishes. DNA will be extracted from the fungi, PCR amplified using fungi-specific universal primers, and then sequenced. DNA sequences obtained will be compared to those available in public databases to facilitate identification of corn pathogens and the commercial biological control agents. A 16S metagenomic sequencing will also be conducted to comprehensively characterize the bacterial and fungal communities associated with tar spot infected corn debris, with and without treatment with commercial biopesticides. This analysis will facilitate the identification of microbial communities that promote or inhibit the growth of P. maydis and potentially propel the discovery of new candidate biocontrol agents that could be developed for the management of tar spot disease.