IMPROVING FRUIT SAFETY OF BLOSSOM PROTECT FOR ORGANIC FIRE BLIGHT MANAGEMENT IN THE EAST

Fire blight is one of the most difficult diseases to control in organic apple and pear production due to its devastating damage and the lack of effective control measures. Blossom Protect, a biological control comprised of the yeast-like fungiAureobasidium pullulansas the active ingredient, is the most effective biocontrol control material of fire blight and is now considered 'foundational' for effective fire blight control in organic apple orchards in western United States. Blossom Protect, however, has a drawback in that it is a cause of fruit russeting, a disorder of the cuticle of developing fruitlets that compromises quality, especially in humid climates. Consequently, in the more humid eastern U.S., the risk of fruit russeting from Blossom Protect has slowed the development of effective organic management of fire blight.Therefore, this risk is a critical barrier for organic transition within the region, and the development of methods that maintain fruit quality by mitigating russeting risk from Blossom Protect is an important research priority.In this project, we aim to test three russeting management strategies, with the following specific objectives:Objective. 1.Test the susceptibility ofA. pullulansto different OMRI-listed fungicides.Objective. 2.Determine the russeting mitigation effect of using OMRI-listed fungicides to remove/reduceA. pullulanspopulation at petal fall, when russeting risk increases. The "Protection and Clearing" strategy.Objective. 3.Determine the effect of OMRI-listed plant growth regulators and micronutrients in improving fruit finish.The "Remedy" strategyObjective. 4.Balance fire blight disease suppression and russeting risk by fine-tuning the application dosage, frequency and timing of Blossom Protect. The "Adjust" strategyObjective. 5.Develop an integrated, multi-channel program for fire blight suppression and russeting mitigation.Objective. 6.Disseminate the knowledge on russeting mitigation practices to the organic tree fruit community.The long-term goalis to provide organic growers in the east with effective management tools for fire blight while maintaining the high quality of fruits.