WSU Tree Fruit Research & Extension Center

Organic & Integrated Tree Fruit Production

Wednesday, May 6, 2015

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 (Jan. 2014).   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 (March 2014). 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). An eOrganic webinar on the topic will be offered on March 17, 2015.

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. March 2012.

Lack of evidence for direct linkage of plant agriculture use of oxytetracycline to antibiotic resistance in human pathogens. V. Stockwell and D. Granatstein. 2013

Antibiotic residues on plant tissues. V. Stockwell, D. Granatstein, and M. Grieshop. 2013.

Oxytetracycline residue study.  Apples from 7 different Washington State orchards were tested for residues at harvest and no residues were detected. 2013.

Research Reports

Smith, T. 2015. Improving the management of two critical pome fruit diseases. Final report, WA Tree Fruit Research Commission

Norelli, J. and Evans, K. 2015. Incorporating fire blight resistance into Washington apple cultivars. Final report, WA Tree Fruit Research Commission

Johnson, K. 2014. Fire blight management in organic and conventional apple. Final report, WA Tree Fruit Research Commission

Elkins, R. and Lindow, S. 2012. Control of fire blight disease in pear, caused by E.a., using biological control agents, copper, and antibiotics. CA Pear Advisory Board. 

Elkins, R. et al. 2012. Evaluation of delayed-dormant copper as a component of a fire blight IPM program. CA Pear Advisory Board.

Johnson, K. Development of non-antibiotic programs for fire blight control in organic apple and pear. USDA-NIFA IOP. (see below)

Sundin, G. and Grieshop, K. Organic management of fire blight in a post-antibiotic era: developing, evaluating, and delivering options for apples grown in humid climates. USDA-NIFA IOP.  (see below)

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.

 

USDA CRIS REPORTS

Sundin and Grieshop; Michigan
ACCESSION NO:
1000292 SUBFILE: CRIS
PROJ NO:
MICL05075 AGENCY: NIFA MICL
PROJ TYPE: OTHER GRANTS PROJ STATUS: NEW
CONTRACT/GRANT/AGREEMENT NO: 2013-51106-20944 PROPOSAL NO: 2013-03968
START: 01 SEP 2013 TERM: 31 AUG 2016
GRANT AMT: $464,482 GRANT YR: 2013
AWARD TOTAL:$464,482

INVESTIGATOR: Sundin, G.; Grieshop, MA.

PERFORMING INSTITUTION:
Plant, Soil, and Microbial Sci
MICHIGAN STATE UNIV
EAST LANSING, MICHIGAN 48824

ORGANIC MANAGEMENT OF FIRE BLIGHT IN A POST-ANTIBIOTIC ERA: DEVELOPING, EVALUATING, & DELIVERING OPTIONS FOR APPLES GROWN IN HUMID CLIMATES

NON-TECHNICAL SUMMARY: Organic apple production east of the Mississippi river is nearing a significant crossroad -- faced with the near-term removal of antibiotics from organic production, growers need novel solutions that they can rely on or production will neither be economically nor biologically feasible due to fire blight disease. This project directly addresses one of the four ORG FY 2013 Priorities - to develop alternatives to antibiotics for fire blight control in organic crops. In a post-antibiotic era, we will evaluate all available NOSB-approved materials to reduce flower infection and improve efficacy. We will take a microbial ecology approach to increasing the colonization potential of two fire blight antagonists, the bacterium Pantoea agglomerans (Bloomtime Biological) and the yeast Aureobasidium pullulans (Blossom Protect). We will use a contact sterilant as a niche-clearing agent on flowers prior to inoculation of antagonists. Two promising new low copper formulation materials, Previsto and Cueva, will also be evaluated. Various combinations of antagonists, copper, and other materials will be tested for compatibility, and optimized integrated treatment programs will be developed, and examined at farm scale. The long-term goals of this project are to develop sound, sustainable, efficacious organic disease-control programs for the management of fire blight in organic apple orchards in humid environments, and to deliver these new management programs to growers through innovative and comprehensive Extension programs. Extension activities will include a yearly on-farm field day with demonstration plots available to growers, production and dissemination of scripted videos outlining project research results, regular grower presentations, and site visits.

OBJECTIVES: The major long-term goals of this projectare to develop sound, sustainable, efficacious organic disease-control programs for themanagement of fire blight in organic apple orchards in humid environments, and to deliverthese new management programs to growers through innovative and comprehensive Extension programs.

APPROACH: 1. We propose to examine the effects of the indigenous apple flower microflora on colonization of P. agglomerans and A. pullulans by examining colonization (% incidence and population size) of flowers that were either non-treated or treated with OxiDate 2.0 (Biosafe Systems; East Hartford, CT) at the labeled rate of 128 fl. oz per 100 gallons of water. OxiDate is OMRI-approved and is a hydrogen dioxide product that functions as a contact sterilant. OxiDate has essentially no residual activity; there is a 0 hr re-entry interval on the label following its use. Our plan is to use this material as a niche-clearing treatment of the apple flower and stigma and to determine the effect of this pre-sterilization step on subsequent colonization by P. agglomerans or A. pullulans. Experiments under Objective 1 will be conducted in small plot treatments using a randomized complete block design and at least 5 single-tree replicates. These small size experiments are typically utilized in efficacy studies and provide sufficient replication to yield robust results. Treatments yielding positive results will be examined at farm scale under Objective 4. 2. Copper efficacy trials testing Previsto and Cueva will be conducted at the MSU Plant Pathology farm using trees inoculated with the fire blight pathogen Erwinia amylovora. Disease ratings will yield stastically-analyzed efficacy data for blossom blight and shoot blight symptoms. 3. Use timing of application studies will be conducted to determine the potential compatibility of Blossom Protect and Bloomtime Biological with the copper compounds Previsto and Cueva. 4. Research results from the various efficacy experiments and integration experiments will yield optimized treatments that will then be examined at farm scale. Three certified organic grower cooperators in Michigan will test optimized programs in large scale plots on their farms. These experiments will be of sufficient scale that positive results would be expected to be directly applicable to other organic growers.

PROGRESS: 2013/09 TO 2014/08
Target Audience: The target audience for this work is the grower community (apple, cherry, peach), extension agents, representatives for chemical companies and disease scouting consultants, mainly in Michigan but in other states as well. Additional target audience is the research community of plant pathologists that work on bacterial diseases of tree fruit and bacterial pathogens as well as the microbiology research community that works on bacterial pathogenesis. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Training opportunities include mentoring of a PhD graduate student Kim Lesniak. How have the results been disseminated to communities of interest? Results have been disseminated to grower audiences, especially organic apple growers, through presentations at grower meetings, in particular the Great Lakes Fruit and Vegetable EXPO Organic Tree Fruit session in December 2013. What do you plan to do during the next reporting period to accomplish the goals? Continued studies will be done in attempts to optimize the use of Blossom Protect for fire blight management under Michigan conditions. We also will be examining comaptibility with copper and other fungicides. Copper would be used to increase the overall level of fire blight control and other fungicides will be used as needed for apple scab control.

IMPACT: 2013/09 TO 2014/08
What was accomplished under these goals? We conducted research aimed at determining the best use practices for application of the yeast biological control agent Blossom Protect for fire blight management. We used varying numbers of applications and timings of Blossom Protect, and also examined the effect of using a contact sterilant Oxidate prior to Blossom Protect application. By tracking yeast populations (Aureobasidium pullulans) on flowers, we determined that the use of Oxidate enabled better colonization of flowers by the yeast, and colonization following two applications of Blossom Protect was equivalent to that after four applications.

PUBLICATIONS (not previously reported): 2013/09 TO 2014/08
No publications reported this period.
______________________________________

Johnson, Smith, Elkins; OR, WA, CA

ACCESSION NO: 0226439 SUBFILE: CRIS
PROJ NO: ORE00281 AGENCY: NIFA ORE
PROJ TYPE: OTHER GRANTS PROJ STATUS: EXTENDED
CONTRACT/GRANT/AGREEMENT NO: 2011-51300-30770 PROPOSAL NO: 2011-01965
START: 01 SEP 2011 TERM: 31 AUG 2015
GRANT AMT: $0 GRANT YR: 2014
AWARD TOTAL:$475,835

INVESTIGATOR: Johnson, K. B.

PERFORMING INSTITUTION:
Botany and Plant Pathology
OREGON STATE UNIVERSITY
CORVALLIS, OREGON 97331

DEVELOPMENT OF NON-ANTIBIOTIC PROGRAMS FOR FIRE BLIGHT CONTROL IN ORGANIC APPLE AND PEAR

NON-TECHNICAL SUMMARY: Fire blight is a destructive and feared disease of apple and pear. Presently, antibiotics are the most effective materials used to prevent this tree-killing disease, but actions by the National Organic Standards Board could prohibit their use in organic agriculture beginning in 2014. Biological control of fire blight has been researched for decades, but has not been fully integrated within the context of organic production. In 2009, at stakeholder request, we initiated research on non-antibiotic control of fire blight. Stakeholders identified two objectives: 1) development of effective non-antibiotic programs based on combinations of registered products, and 2) in apple, integration of these programs with bloom thinning. In response, this project will a) characterize, under controlled conditions, the relative abilities of registered biologicals to inhibit the fire blight pathogen on floral surfaces; b) evaluate in experimental orchards integrated non-antibiotic programs for fire blight control and the effect of treatment frequency on program effectiveness; c) in apple, evaluate if early bloom thinning treatments contribute to fire blight control, and how to integrate additional non-antibiotic treatments with a bloom thinning protocol; and d) monitor commercial organic pear and apple orchards for establishment of biologicals in flowers, for the presence of the fire blight pathogen during bloom, and for the resulting severity of the disease. In this process, we will work closely with organic producers, and disseminate the data regionally and nationally via eOrganic webinars, an online course, and through traditional methods. Stakeholders will be involved continuously in on-farm research, data review, and critique of suggested recommendations.

OBJECTIVES: Fire blight is a destructive and feared disease of apple and pear. Presently, antibiotics are the most effective materials used to prevent this tree-killing disease, but actions by the National Organic Standards Board have made this unlikely after 2014. Biocontrol of fire blight has been researched for decades, but has not been fully integrated within the context of organic production. In 2009, at stakeholder request, we initiated research on non-antibiotic control of fire blight. Stakeholders identified two objectives: 1) development of effective non-antibiotic programs based on combinations of registered products, and 2) in apple, integration of these programs with bloom thinning. In response, this project will: Objective 1: Under controlled conditions, characterize the abilities of three biological products to inhibit growth of the fire blight pathogen on stigmas and on nectaries of pome fruit flowers; Objective 2: In experimental orchard trials, evaluate integrated non-antibiotic programs for fire blight control, and the degree to which the effectiveness of these programs is influenced by frequency of treatment applications; Objective 3: In apple, evaluate the degree to which the early bloom treatments of lime sulfur and fish oil contribute to fire blight control, and how to integrate additional non-antibiotic treatments with the fruit thinning protocol; Objective 4: Monitor commercial organic pear and apple orchards within Washington, California and Oregon for establishment of applied biocontrol agents in flowers, for the presence of the fire blight pathogen during bloom, and for the resulting severity of the disease; and Objective 5: Teach integrated, non-antibiotic fire blight control to the organic tree fruit Community of Practice.

APPROACH: In the planned research, we are hypothesizing that satisfactory, non-antibiotic suppression of fire blight can be achieved by integrating the varied properties of the registered biological control agents. We will document these varied properties by examining in a controlled environment the degree to which these agents suppress growth of the fire blight pathogen on stigmas (the pathogen's principle site of epiphytic increase) and on the floral nectary (the site of infection). Of particular interest is the location where A. pullulans, the yeast in Blossom Protect, most strongly inhibits the E. amylovora, which is poorly understood. Understanding the relative abilities of these biological agents to inhibit pathogen growth on floral stigmas and nectaries will aid in determining the need for and order of materials applied in a non-antibiotic, integrated program. In the field, variations of integrated programs will be evaluated with the goal of finding the most effective program with the least complexity and cost. In addition, in apple, we will evaluate the degree to which the early bloom thinning treatments contribute to fire blight control, and how to integrate additional non-antibiotic treatments with the bloom thinning protocol. All experiments will be replicated and the data collected on microbial populations and on fire blight disease will be subjected to analysis of variance. By the end of the project it is expected that all of the biological products used in this study will be available commercially, and thus an integrated disease control strategy can be implemented immediately by organic growers. This project also will devoted to outreach and to monitoring the fate of applied biological agents in commercial orchards. The primary purposes of this on-farm objective are to interact with advisors and growers to present and discuss approaches to non-antibiotic fire blight control, and to evaluate the performance of biocontrol products in the commercial-scale, organic environment. By sampling multiple orchards from three states, we expect to obtain data to characterize the variability in establishment of microbial agents among organic orchards employing similar practices. Variation among orchards in establishment of microbial agents in flowers will be followed up on to attempt to identify practices (e.g., time of treatment, sprayer speed, water volume, heat units after spraying, timing in relation to bloom thinning) that contribute to variation. In previous years, we have developed tools to measure if biological agents are establishing in flowers as intended, and we have also developed a molecular detection protocol to determine if and when the fire blight pathogen has become active within orchards. During these monitoring studies, we will communicate directly with growers and advisors, collect and evaluate samples of flowers from their orchards, and provide immediate feedback on our findings of biocontrol agent establishment and pathogen detection. Additional outreach will occur through eOrganic webinars and web-based publications as well as via traditional methods.


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