Organic Fire Blight Prevention Project
The Organic Center (TOC) has completed a project providing critically needed information on how to prevent fire blight from decimating apple and pear orchards without the use of antibiotics. Fire blight is a serious problem for apple and pear growers in the US. Unlike some fruit pathogens, fire blight doesn’t just damage or destroy that season’s fruit – it can kill the entire tree. It is caused by the bacteria Erwinia amylovora, and is easily spread among trees and orchards. With growers now spending up to $20,000 per acre to establish an orchard, the risk of severe tree injury or loss from fire blight needs to be controlled.
Fire blight can infect trees at different points during the growing season. Bloom infection is the most common in western states, while shoot infection is more common in the Midwest and East. Copper products and the antibiotics streptomycin and oxytetracycline have been the key controls used by many organic growers since before the NOP until now. Oxytetracycline will sunset in October 2014 (streptomycin most likely as well) and thus growers need to implement non-antibiotic control programs.
Dr. Ken Johnson, Oregon State University, is leading a three-state project on non-antibiotic control of fire blight in organic orchards. Progress is being made and new control materials are becoming available. The project will be completed in 2015 with grower-oriented publications to follow, leaving growers with minimal guidance and experience for preventing fire blight without antibiotics in the interim.
The lack of current information on alternatives to antibiotic use in the prevention of fire blight could cause serious repercussions in the organic apple and pear industry. Recent polls done by David Granatstein, Sustainable Agriculture Specialist at Washington State University, show that some 70% or more of organic apple and pear producers in that state (the primary producer in the country) will consider switching some or all production to conventional management if an effective and reliable alternative for fire blight control is not available by the time oxytetracycline sunsets. This couldn’t come at a worse time, since organic apple and pear demand is at an all-time high. If US production declines, organic apple and pear prices could spike, or imports from South America (where the disease is not present) could greatly increase.
To address the issue of alternatives to antibiotics in fire blight control the Organic Center funded a project, in collaboration with David Granatstein and Harold Ostenson, reporting on lessons learned from a systems approach to non-antibiotic fire blight control which has been successfully used by dozens of Pacific Northwest organic orchardists who were maintaining compliance for export to the EU. The strategies used along with currently available materials provide a “lessons learned” knowledge base for other organic orchardists to refer to as they are required to move to non-antibiotic control after October 2014, and can be combined with results from on-going research with several new materials as they become available.
The project is published as a report written for growers, going over methods for controlling fire blight holistically, and covering issues such as sanitation, vigor control, sequence and timing of control materials, spray coverage, and varietal susceptibility. The goal is to help fill the “knowledge gap” created by the 2014 sunset of oxytetracycline and to encourage growers to begin testing alternatives now. Additionally, when Dr. Johnson’s project is completed, their results can be combined with the TOC report to give growers the benefit of the latest research as well as field-proven strategies.
To download the full Critical Issue Report on controlling fire blight in organic orchards click here.