Oregon State University researchers have proven the effectiveness of two organic alternatives for controlling fire blight. Scientists found that spraying a yeast-based product and new water-soluble copper products at the beginning of the growing season provided protection from the bacterial disease. Spread by bees and rain, fire blight remains dormant in trees over winter and infects flowers in spring.
Once infected, growers can only stop the disease by cutting out infections, which can prove fatal in some cases. In OSU trials, researchers tested the commercially available Blossom Protect, a yeast that clings to apple blossoms and pears and prevents colonization by fire blight bacteria. In apples, it was 90 percent effective in controlling fire blight when sprayed after lime sulfur to reduce crop load.
Copper is another option in fighting fire blight, and it has been used for for almost a century. Heavy applications however can be toxic to trees and can create rough blemishes on fruit, known as russeting. New water-soluble copper products, such as Cueva and Previsto, contain low concentrations of the metal, which minimizes its negative effects while still combating fire blight. The research team also prepared a webinar on non-antibiotic treatment of fire blight, available here. This information was first shared in the October 2014 issue of Acres U.S.A.