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 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 when sprayed after lime sulfur to reduce crop load. Copper has been used for fire blight for almost a century, but heavy applications can be toxic to trees or 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 lessens its negative effects while still combating fire blight. The research team prepared a webinar on non-antibiotic treatment of fire blight, bit.ly/FireBlightWebinar.
This article appears in the October 2014 issue of Acres U.S.A.