This Small Business Innovation Research (SBIR) Phase I project proposes to develop a novel method to combat Erwinia amylovora (Ea), a causative agent of fire blight. Fire blight has emerged as the most devastating disease of apple and pear trees worldwide. Many growers apply streptomycin or oxytetracycline multiple times during bloom and following plant injuries to prevent the growth of Ea. Resistant strains have been isolated and resistance is expected to proliferate directly in the human food chain. Here we propose to replace these antibiotics with the microscopic predators of bacteria, slime molds, which are benign to humans, animals, and plants. As advancement in agriculture, bacterial predators represent a new proprietary biocontrol approach. Whereas the proposed project will focus on reducing orchard carriage of Ea, the general approach should be extensible to treating agricultural infections and contaminations of many other species of bacterial pathogens. The broader impact/commercial potential of this project, if successful, will be a novel method for the treatment bacterial infections in fruit and vegetable crops. Among fruit crops grown commercially in the U.S., apples and pears rank third in terms of area in production and utilized value. A pressing issue driving the need for an alternative to current treatments is the inevitable ban on the use of clinical antibiotics in agriculture. For organic orchardists, this ban will take effect in 2014, and will leave a significant gap in the marketplace. From a timing perspective, this gives agrochemical industry an immediate opportunity to fill this gap and gain quick acceptance of predator-based new technology. Furthermore, many agricultural diseases demand the development of fundamentally new treatments effective against biofilm-encased bacteria, which are refractory to antibiotics. Alarmingly, there is currently no single treatment that can efficiently kill biofilms even though the incidence of reoccurring infections indicate that biofilms exist in orchards throughout the world. Antibiotics typically kill only growing cells whereas predators we will harness can consume bacteria whether the bacteria are free-living or biofilm-encased. The $300M apple/pear market is the first target market for predator-based biocontrol. Future markets including citrus, grapes, and vegetables, will bring the total addressable agricultural market alone to >$1B.