Seedborne Fungal Detection Differs with Seed Assay Method, and Fungal Diversity and Abundance Are Impacted by Fungicide Treatment, Harvest Timing, and Storage Environment

Previous studies have shown that foliar fungicides increase the abundance of Diaporthe spp. in mature soybean seeds, thereby reducing seed quality and potentially increasing seedling, stem, and pod disease in subsequent plantings. To mitigate this, we examined a fungicide containing mefentrifluconaz...

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Main Authors: Jean Carlson Batzer, Amin Shirazi, Daniel Gill, Evelyn Platner-Heidt, Karl Nicolaus, Alex Bray, Karthika Mohan, Febina M. Mathew, Daren S. Mueller
Format: Article
Language:English
Published: The American Phytopathological Society 2024-12-01
Series:PhytoFrontiers
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Online Access:https://apsjournals.apsnet.org/doi/10.1094/PHYTOFR-06-24-0076-R
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author Jean Carlson Batzer
Amin Shirazi
Daniel Gill
Evelyn Platner-Heidt
Karl Nicolaus
Alex Bray
Karthika Mohan
Febina M. Mathew
Daren S. Mueller
author_facet Jean Carlson Batzer
Amin Shirazi
Daniel Gill
Evelyn Platner-Heidt
Karl Nicolaus
Alex Bray
Karthika Mohan
Febina M. Mathew
Daren S. Mueller
author_sort Jean Carlson Batzer
collection DOAJ
description Previous studies have shown that foliar fungicides increase the abundance of Diaporthe spp. in mature soybean seeds, thereby reducing seed quality and potentially increasing seedling, stem, and pod disease in subsequent plantings. To mitigate this, we examined a fungicide containing mefentrifluconazole, fluxapyroxad, and pyraclostrobin applied during the R3 growth stage. We compared the seedborne fungal community from soybeans harvested at full maturity and 2 to 3 weeks later to assess fungal colonization. Six trials were conducted in Iowa and South Dakota in 2021 and 2022. Asymptomatic, recently harvested seed was assayed using either an agar-plate or a seed-blotter test, and the results were compared. The agar-plate method involved disinfesting seeds in sodium hypochlorite and ethanol and then transferring them to acidified water agar plates. Fungal isolates were identified using morphology and DNA sequences. This method detected 562 fungal isolates from 25 species and 14 genera. Dry conditions reduced seed infection, but a 2-week delay in harvest increased the likelihood of Alternaria and Cercospora infection in nontreated controls. The seed-blotter test involved disinfesting seeds, placing them on blotter paper, and incubating them. This assay detected higher numbers of fungal infected seed, with Aspergillus as the dominant genus. Storage conditions significantly impacted fungal presence, with more Aspergillus in seeds stored in a shed than in the cooler. Both assay methods showed that the fungicide treatment reduced the number of seeds infected with Alternaria, Cercospora, and Aspergillus. [Figure: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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spelling doaj-art-da822443613c4c8cb1732dc2e916631c2025-08-20T02:39:15ZengThe American Phytopathological SocietyPhytoFrontiers2690-54422024-12-014476778010.1094/PHYTOFR-06-24-0076-RSeedborne Fungal Detection Differs with Seed Assay Method, and Fungal Diversity and Abundance Are Impacted by Fungicide Treatment, Harvest Timing, and Storage EnvironmentJean Carlson Batzer0Amin Shirazi1Daniel Gill2Evelyn Platner-Heidt3Karl Nicolaus4Alex Bray5Karthika Mohan6Febina M. Mathew7Daren S. Mueller8Plant Pathology, Entomology, and Microbiology Department, Iowa State University, Ames, IA 50011, U.S.A.Department of Statistics, Iowa State University, Ames, IA 50011, U.S.A.Department of Plant Pathology, North Dakota State University, Fargo, ND 58105, U.S.A.Plant Pathology, Entomology, and Microbiology Department, Iowa State University, Ames, IA 50011, U.S.A.Plant Pathology, Entomology, and Microbiology Department, Iowa State University, Ames, IA 50011, U.S.A.Plant Pathology, Entomology, and Microbiology Department, Iowa State University, Ames, IA 50011, U.S.A.Department of Plant Pathology, North Dakota State University, Fargo, ND 58105, U.S.A.Department of Plant Pathology, North Dakota State University, Fargo, ND 58105, U.S.A.Plant Pathology, Entomology, and Microbiology Department, Iowa State University, Ames, IA 50011, U.S.A.Previous studies have shown that foliar fungicides increase the abundance of Diaporthe spp. in mature soybean seeds, thereby reducing seed quality and potentially increasing seedling, stem, and pod disease in subsequent plantings. To mitigate this, we examined a fungicide containing mefentrifluconazole, fluxapyroxad, and pyraclostrobin applied during the R3 growth stage. We compared the seedborne fungal community from soybeans harvested at full maturity and 2 to 3 weeks later to assess fungal colonization. Six trials were conducted in Iowa and South Dakota in 2021 and 2022. Asymptomatic, recently harvested seed was assayed using either an agar-plate or a seed-blotter test, and the results were compared. The agar-plate method involved disinfesting seeds in sodium hypochlorite and ethanol and then transferring them to acidified water agar plates. Fungal isolates were identified using morphology and DNA sequences. This method detected 562 fungal isolates from 25 species and 14 genera. Dry conditions reduced seed infection, but a 2-week delay in harvest increased the likelihood of Alternaria and Cercospora infection in nontreated controls. The seed-blotter test involved disinfesting seeds, placing them on blotter paper, and incubating them. This assay detected higher numbers of fungal infected seed, with Aspergillus as the dominant genus. Storage conditions significantly impacted fungal presence, with more Aspergillus in seeds stored in a shed than in the cooler. Both assay methods showed that the fungicide treatment reduced the number of seeds infected with Alternaria, Cercospora, and Aspergillus. [Figure: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.https://apsjournals.apsnet.org/doi/10.1094/PHYTOFR-06-24-0076-Rassessment methodGlycine maxlogistic regressionmicrobial communitiesmolecular identificationquinone outside inhibitor (QoI) fungicides
spellingShingle Jean Carlson Batzer
Amin Shirazi
Daniel Gill
Evelyn Platner-Heidt
Karl Nicolaus
Alex Bray
Karthika Mohan
Febina M. Mathew
Daren S. Mueller
Seedborne Fungal Detection Differs with Seed Assay Method, and Fungal Diversity and Abundance Are Impacted by Fungicide Treatment, Harvest Timing, and Storage Environment
PhytoFrontiers
assessment method
Glycine max
logistic regression
microbial communities
molecular identification
quinone outside inhibitor (QoI) fungicides
title Seedborne Fungal Detection Differs with Seed Assay Method, and Fungal Diversity and Abundance Are Impacted by Fungicide Treatment, Harvest Timing, and Storage Environment
title_full Seedborne Fungal Detection Differs with Seed Assay Method, and Fungal Diversity and Abundance Are Impacted by Fungicide Treatment, Harvest Timing, and Storage Environment
title_fullStr Seedborne Fungal Detection Differs with Seed Assay Method, and Fungal Diversity and Abundance Are Impacted by Fungicide Treatment, Harvest Timing, and Storage Environment
title_full_unstemmed Seedborne Fungal Detection Differs with Seed Assay Method, and Fungal Diversity and Abundance Are Impacted by Fungicide Treatment, Harvest Timing, and Storage Environment
title_short Seedborne Fungal Detection Differs with Seed Assay Method, and Fungal Diversity and Abundance Are Impacted by Fungicide Treatment, Harvest Timing, and Storage Environment
title_sort seedborne fungal detection differs with seed assay method and fungal diversity and abundance are impacted by fungicide treatment harvest timing and storage environment
topic assessment method
Glycine max
logistic regression
microbial communities
molecular identification
quinone outside inhibitor (QoI) fungicides
url https://apsjournals.apsnet.org/doi/10.1094/PHYTOFR-06-24-0076-R
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