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United States Department of Agriculture

Agricultural Research Service

Title: A Novel Ranking Method and Evaluation of the Commercial Development Potential of Bacterial Antagonists of Fusarium Dry Rot

item Schisler, David
item Slininger, Patricia
item Burkhead, Karen
item Kleinkopf, G - UNIV OF IDAHO
item Hanson, L - CORNELL UNIV
item Bothast, Rodney
item Ostrowski, R - UNITED AGRI PRODUCTS

Submitted to: International Congress of Plant Pathology Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 16, 1998
Publication Date: N/A

Technical Abstract: Ten strains of Fusarium sambucinum were isolated from potato tubers collected in the northeastern U.S. Five antagonists, produced in a commercially feasible liquid medium, decreased disease incited by all F. sambucinum strains by 34%. However, antagonists frequently were more effective when produced on 1/5 tryptic soy broth agar (TSBA/5)(43% disease decrease). When antagonists were produced on nutritionally identical medi in liquid and solid form, antagonists were highly effective against all pathogen strains, though antagonists produced in TSB/5 were less efficacious than those produced on TSBA/5 (87% vs. 92% disease decrease, respectively). Rankings of antagonists' effectiveness changed with the production media and the pathogen strain. Selecting antagonists using the criteria of efficacy against a range of pathogen strains and antagonist amenability to production in liquid culture increases the likelihood of choosing strains with commercial development potential. Gram-negative bacterial strains with commercial development potential were selected for pilot and bin trials in Idaho and North Dakota. Fluorescent Pseudomonas strain S22:T:04 (~1 x 10**8 cfu/ml) decreased the level of dry rot in year one trials when coinoculated with the pathogen compared to controls and the fungicide Mertect 340F. In second year studies, P. fluorescens strain P22:Y:05 and Enterobacter cloacae strain S11:T:07 (~4 x 10**8 cfu/ml) controlled F. sambucinum (25% and 17% avg. disease decrease, respectively) but not F. coeruleum when antagonists were applied 24 h after pathogen inoculation. E. cloacae S11:T:07, produced in liquid culture, reduced naturally occurring levels of dry rot by an average of 21% for all year three bin trials compared to 14% for Mertect 340F.

Last Modified: 4/18/2015
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