Abstracts of Presentations at Plant Health 2024

In our study targeting shoot blight on young 'Bartlett' pear trees caused by Erwinia amylovora and the prevention of fire blight canker formation, we assessed advanced preventive spray treatments.Our investigation focused on foliar spray applications, testing various rates of Reynoutria sachalinensis (giant knotweed) extract (RSE) alone and combined with Apogee, a plant growth regulator.Additionally, we examined Apogee alone, Apogee with Cueva (copper octanoate), and traditional antibiotics such as streptomycin and oxytetracycline.Applying 153.6 fl oz/A and three 32 fl oz/A of RSE on 6-year-old 'Bartlett' trees yielded significant results, achieving 78.3% to 100% control of shoot blight severity (SBS) and 76.8% to 100% control of canker incidence (CI).While other RSE rates, including the RSE-Apogee combination, demonstrated lower effectiveness, Apogee alone showed modest control.However, combining Apogee with Cueva exhibited promising results, achieving 89.4% control of SBS and 88.6% control of CI.Despite antibiotics showing 100% control, their suitability for summer application is limited due to concerns regarding antibiotic resistance.Overall, our findings suggest that applying RSE at specific rates and the Apogee-Cueva combination consistently offer effective control of shoot blight and cankers in pear trees.