DisplayTitle

Bacterial blossom blast of cherry and other stone fruits is one phase of bacterial canker caused by <i>Pseudomonas syringae</i> pv. <i>syringae</i> or to a lesser extent by<i> P. syringae</i> pv. <i>morsprunorum</i>. Blast is associated with wetness and cold temperatures during bloom and results in flower clusters that collapse, turn brown to black are papery when dry, and eventually drop. Some scion-rootstock combinations (e.g., cv. Coral Champagne cherry on Mahaleb rootstock) are more susceptible than others. In addition to cultural practices, only copper products are currently widely available for the management for blossom blast. Copper, however, is not highly effective, is potentially damaging to blossoms and new growth, and resistance to copper occurs in many pathogen populations. For the evaluation of new bactericidal treatments that could be used in combination with fungicides during bloom, we developed a partial emasculation-inoculation method that proved highly effective for reproducing the disease in the field. New bactericidal treatments were also evaluated in natural incidence studies. Commercial formulations of kasugamycin, the biocontrol <i>Streptomyces lydicus</i>, and oxytetracycline proved highly effective; whereas copper had little or no effect. The registrants of kasugamycin and the biocontrol support registration of their products for the management of bacterial blast and these will be the first treatments ever registered in the United States for effective management of this disease. <p><p>Keywords: Bacteria-Phytoplasma-Spiroplasma-Fastidious Prokaryote, Fruits-Nuts, Cherry