Reduction of Pythium Damping-Off in Soybean by Biocontrol Seed Treatment

Mirian F. Pimentel, Erika Arnao, Amanda J. Warner, Leonardo F. Rocha, Arjun Subedi, Nariman Elsharif, Martin I. Chilvers, Rashelle Matthiesen, Alison E. Robertson, Carl A. Bradley, Danilo L. Neves, Dianne K. Pedersen, Ursula Reuter-Carlson, Jonathan V. Lacey, Jason P. Bond, Ahmad M. Fakhoury

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Pythium spp. is one of the major groups of pathogens that cause seedling diseases on soybean, leading to both preemergence and postemergence damping-off and root rot. More than 100 species have been identified within this genus, with Pythium irregulare, P. sylvaticum, P. ultimum var ultimum, and P. torulosum being particularly important for soybean production given their aggressiveness, prevalence, and abundance in production fields. This study investigated the antagonistic activity of potential biological control agents (BCAs) native to the U.S. Midwest against Pythium spp. First, in vitro screening identified BCAs that inhibit P. ultimum var. ultimum growth. Scanning electron microscopy demonstrated evidence of mycoparasitism of all potential biocontrol isolates against P. ultimum var. ultimum and P. torulosum, with the formation of appressorium-like structures, short hyphal branches around host hyphae, hook-shaped structures, coiling, and parallel growth of the mycoparasite along the host hyphae. Based on these promising results, selected BCAs were tested under field conditions against six different Pythium spp. Trichoderma afroharzianum 26 used alone and a mix of T. hamatum 16 + T. afroharzianum 19 used as seed treatments protected soybean seedlings from Pythium spp. infection, as BCA-treated plots had on average 15 to 20% greater plant stand and vigor than control plots. Our results also indicate that some of these potential BCAs could be added with a fungicide seed treatment with minimum inhibition occurring, depending on the fungicide active ingredient. This research highlights the need to develop tools incorporating biological control as a facet of soybean seedling disease management programs. The harnessing of native BCAs could be integrated with other management strategies to provide efficient control of seedling diseases.

Original languageEnglish
Pages (from-to)2403-2414
Number of pages12
JournalPlant Disease
Volume106
Issue number9
DOIs
StatePublished - Sep 2022

Bibliographical note

Funding Information:
This research was partially funded by the Soybean Checkoff through the United Soybean Board (USB) and the North Central Soybean Research Program (NCSRP). The authors appreciate the hard work of staff involved in planting and data collection in Michigan and Iowa: Janette Jacobs, Adam Byrne, and John Boyse. Thank you, Dr. Danilo Neves, for helping with the fungicide sensitivity assay. We also thank the staff and graduate assistants from the Integrated Microscopy Center at Southern Illinois University, Carbondale for their valuable help with the scanning electron microscope.

Publisher Copyright:
© 2022 The American Phytopathological Society.

Keywords

  • biological control
  • Clonostachys rosea
  • fungicide tolerance
  • integrated disease management
  • mycoparasitism
  • seedling blight
  • soybean seedling diseases
  • Trichoderma spp

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science

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