EVALUATION OF BACTERICIDES FOR CONTROL OF FIRE BLIGHT OF PEARS AND APPLES CAUSED BY ERWINIA AMYLOVORA

Fire blight, caused by the bacterium Erwinia amylovora, is a very destructive disease of pome fruit trees worldwide that is difficult to control.
Even with an integrated program of chemical control combined with sanitation and orchard management, fire blight is almost impossible to eliminate and pathogen derived resistance had developed.
New and more effective materials for fire blight control are needed that target multiple sites of action or have a mode of action different from currently used bactericides that is not phytotoxic.
During the past three years we evaluated a broad spectrum biocide (DB 918-48C – Dow Chemical) that is registered as a water treatment and is highly toxic at low concentrations in in vitro assays against Erwinia and Xanthomonas. Several formulations of this compound significantly reduced disease incidence in field trials with pear, providing control similar to terramycin.
Other compounds evaluated that showed fire blight efficacy were the acidified hydrogen peroxide Zerotol, the antibiotic Starner, the activated host resistance compound Vacciplant, and new copper Bioacumen and silver-based Axenohl.
Zerotol, Starner, and Axenohl all provided similar levels of control as terramycin.
The new copper formulation Bioacumen showed no clear advantage from other copper products.
The efficacy of the systemic acquired resistance material Vacciplant was variable but may be used effectively with terramycin or streptomycin.
Combination sprays of the biological control agents Pseudomonas fluorescens A506 and Serenade with Apogee showed efficacy against fire blight and their use appears enhanced with surfactants such as Breathru.

X International Workshop on Fire Blight

J. Adaskaveg, H. Förster, B.A. Holtz, E. Hoffman, D. Gubler, E. Erickson

Zerotol, Vacciplant, Starner, Bioacumen, Serenade, Apogee, Pseudomonas fluorescens A506

https://doi.org/10.17660/ActaHortic.2006.704.39