Fire Blight Control in Organic Apples and Pears
Fire blight is a serious bacterial disease of apples and pears across the U.S. It typically infects the blossoms of the tree, and various treatments may be applied at this time before any fruit is developed. The National Organic Program allowed for the use of the antibiotics streptomycin and oxytetracycline for control of fire blight on organic apples and pears since its inception in 2002. These materials, while produced by naturally occurring microorganisms, are considered synthetic and thus listed on the National List of Allowed Synthetics. They undergo a sunset review every 5 years. Recently the National Organic Standards Board (NOSB) voted to phase out these materials in October 2014, based on what could be considered incomplete information. An Organic Tree Fruit Industry Work Group was formed at the request of the NOSB to help keep them informed of progress with non-antibiotic control techniques. Below are some information resources for stakeholders interested in learning more about the disease and its control in organic orchards.
Note: Within some of the following resources, pesticides are discussed which are not yet registered in Washington State. Applicators are reminded that it is your responsibility to check the state registration status of a label before using the product to ensure lawful use and to obtain all necessary licenses, endorsements and permits in advance. Additionally, some pesticides reported in these resources were used under state-authorized experimental permits at rates higher than allowed on the label. Application of a pesticide to a crop or site that is not on the label is a violation of pesticide law and may subject the applicator to civil penalties up to $7,500. In addition, such an application may also result in illegal residues that could subject the crop to seizure or embargo action by WSDA and/or the U.S. Food and Drug Administration.
2014 is the last season in which organic growers can use antibiotics to control fire blight. Now is the time to look at non-antibiotic controls, for which there has been significant progress in the past few years. An annotated presentation by Dr Ken Johnson of Oregon State University outlines possible control strategies. A publication by H. Ostenson and D. Granatstein funded by The Organic Center describes what organic growers in the EU program have done historically and how new control options can be integrated into a systems approach. A webinar by Ken Johnson and Rachel Elkins (Nov. 21, 2014) reviews the latest results after the 2014 season (courtesy of CCOF; content starts at the 22 minute mark).
Antibiotic Residues and Use Patterns on Apples and Pears. 2014. A WSU Extension fact sheet discussing actual field use patterns of antibiotics to control fire blight, and results from two fruit residue testing efforts to develop data on oxytetracycline residues under normal field use.
Fire Blight – Current Products, Research Grants and Regulatory Status. A powerpoint presentation by David Granatstein for a national discussion of the status of fire blight control (October 2014).
Organic fire blight control and the NOSB. An introduction to the disease and recent deliberations regarding its control in organic orchards.
Fire blight testimony by David Granatstein at NOSB Seattle meeting, April 26, 2011.
Fire blight update. Presentation made by the Organic Tree Fruit Industry Work Group at the Nov. 30, 2011, NOSB meeting in Savannah, GA.
Fire blight update. Presentation made by the Organic Tree Fruit Industry Work Group at the October 2012 NOSB meeting in Providence, RI.
The role of tree genetics in controlling fire blight in apples and pears. A short overview of the opportunities and limitations of genetic resistance for control of fire blight.
Alternative fire blight control materials to replace antibiotics. A discussion of existing and emerging control materials and strategies.
Use of streptomycin and oxytetracycline for fire blight management in organic pear production in California. by Dr. Broc Zoller, pear consultant.
Fire blight alternatives funding. A rough estimate of the industry investment in research on non-antibiotic controls.
Estimated economic impact of loss of antibiotics for fire blight control in organic orchards is $8-16 million per year.
eOrganic webinar on non-antibiotic fire blight control. Dr. Ken Johnson, Oregon State University. A discussion of the research to date on the biology of the disease, a new orchard monitoring technuiqe, other control materials and integration of methods.
NEW! January 2013. Short review papers.
Lack of evidence for direct linkage of plant agriculture use of oxytetracycline to antibiotic resistance in human pathogens. V. Stockwell and D. Granatstein.
Antibiotic residues on plant tissues. V. Stockwell, D. Granatstein, and M. Grieshop.
Oxytetracycline residue study. Apples from 7 different Washington State orchards were tested for residues at harvest and no residues were detected.
Other Web Sites
Fire Blight Management in the Pacific Northwest. Tim Smith, Washington State Univ. Extension.
Fire Blight. West Virginia University.
Fire Blight Fact Sheet. Wayne Wilcox, Cornell University.
Models for fire blight on apple and pear. Univ. California IPM program.