Inoculation method impacts symptom development associated with Diaporthe aspalathi, D. caulivora, and D. longicolla on soybean (Glycine max)

Krishna Ghimire, Kristina Petrović, Brian J. Kontz, Carl A. Bradley, Martin I. Chilvers, Daren S. Mueller, Damon L. Smith, Kiersten A. Wise, Febina M. Mathew

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

One hundred fifty-two Diaporthe isolates were recovered from symptomatic soybean (Glycine max) stems sampled from the U.S. states of Iowa, Indiana, Kentucky, Michigan, and South Dakota. Using morphology and DNA sequencing, isolates were identified as D. aspalathi (8.6%), D. caulivora (24.3%), and D. longicolla (67.1%). Aggressiveness of five isolates each of the three pathogens was studied on cultivars Hawkeye (D. caulivora and D. longicolla) and Bragg (D. aspalathi) using toothpick, stem-wound, mycelium contact, and spore injection inoculation methods in the greenhouse. For D. aspalathi, methods significantly affected disease severity (P < 0.001) and pathogen recovery (P < 0.001). The relative treatment effects (RTE) of stem-wound and toothpick methods were significantly greater than for the other methods. For D. caulivora and D. longicolla, a significant isolate × method interaction affected disease severity (P < 0.05) and pathogen recovery (P < 0.001). Significant differences in RTEs were observed among D. caulivora and D. longicolla isolates only when the stem-wound and toothpick methods were used. Our study has determined that the stem-wound and toothpick methods are reliable to evaluate the three pathogens; however, the significant isolate × method interactions for D. caulivora and D. longicolla indicate that multiple isolates should also be considered for future pathogenicity studies.

Original languageEnglish
Pages (from-to)677-684
Number of pages8
JournalPlant Disease
Volume103
Issue number4
DOIs
StatePublished - Apr 2019

Bibliographical note

Publisher Copyright:
© 2019 The American Phytopathological Society.

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science

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