Materials and methods Plant material and Erwinia strains Highly susceptible 'Gala' scions were grafted on 'M.9' root stocks to perform artificial fire blight inoculation and to har vest samples for diagnosis. The 'M.9' rootstocks were obtain ed from Willamette Nursery, Canby, OR. The plants were potted into D40H deepots™ (Stueve and Sons Tangent, OR) containing Sunshine soil mix (Sungrow Horticulture Agawam, MA), and were grown at the Cornell AgriTech greenhouse facilities in Geneva, NY. The greenhouse condi tions were maintained at 21-24 °C temperature with up to 12 h supplemental light. Plants were fertilized once per week with Peters Excel 15–5-15 (ICL Fertilizers, OH) at 200-250 N PPM, and were watered regularly as needed