Development and on-farm training of biologically based methods for integrated crop management of stone fruits in New England

Final Report for LNE09-279

Project Type: Research and Education
Funds awarded in 2009: $195,498.00
Projected End Date: 12/31/2013
Region: Northeast
State: Connecticut
Project Leader:
Dr. Robert Marra
Connecticut Agricultural
Co-Leaders:
Lorraine Los
University of Connecticut
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Project Information

Summary:
Research Component

In order to obtain isolates of bacteria (Xanthomonas arboricola pv. pruni =Xap) and bacteriophage (=”phage”), nineteen orchards in Connecticut, New York, and Massachusetts, were sampled for plant material obtained from peach, nectarine, and plum trees. A total of 121 plant samples were collected and tested for the presence of Xap as well as phage. From these, 23 Xap strains were obtained, purified, and stored. Additionally, 43 phage strains were obtained, identified as Xap-specific bacteriophage based on their ability to form phage plaques on Xap cultures. Laboratory studies were conducted to determine phage diversity, resulting in the conclusion that all 43 phage strains are functionally equivalent, based on cross-reactivity experiments using Xap strains lysogenic for a subset of 15 phage strains from the phage collection. A presentation on the goals, experimental plan, and research results to date was made in December 2010 to Connecticut growers at the annual meeting of the Connecticut Pomological Society. In January 2010, 60 O’Henry peach seedlings were potted and forced in the greenhouse. Efforts at effecting bacterial leaf spot (BLS) symptoms in the greenhouse were unsuccessful due to temperature and humidity limitations of available greenhouse space. All trees underwent a 750-hour chill period following forcing in the greenhouse in February 2011. Detached branch bioassays were attempted in the growth chamber, where conditions can be more accurately controlled. However, these efforts were also unreliable in producing BLS symptoms. Therefore, these efforts have been abandoned; established researchers who have worked on this disease for over 20 years have reported similar difficulties with effecting disease symptoms in greenhouse settings. Three experimental orchards of Sweet Dream peach trees, located in Hamden, Windsor, and Griswold, were planted in 2010 and maintained each year with pruning. In spring 2013, the orchards were used to compare the standard treatment of dormant copper and Mycoshield (oxytetracycline) against two experimental biocontrol treatments (Serenade ASO and Blight Ban A506) and a control of no treatment. We observed minimal disease pressure on the control trees in the Griswold and Windsor orchards, and slightly more in the Hamden orchard. While it was not possible to make conclusive evaluations of the three treatments, these data can be viewed as preliminary, in suggesting that the standard treatment of copper and Mycoshield performed slightly better than either of the two experimental treatments.

Outreach Component

The outreach portion of this project focused on IPM education for stone fruit growers. Outreach included onsite training in grower orchards, presentations at state and regional grower meetings, and the development of a publication entitled “IPM Guidelines for Insects and Diseases of Stone Fruits”. A total of 13 growers with 69 acres of stone fruits were involved with one-on-one IPM training from 2009 through 2011. In addition, three Connecticut growers with 85 acres of stone fruits participated in the Eco Stone Fruit project beginning in 2010 by following protocols developed by the Co-PI and others through Red Tomato. As a result a total of 16 Connecticut stone fruit growers with 154 acres were directly involved with stone fruit IPM through this SARE project. The main components of the Verification Plan were surveys sent to Connecticut growers to assess stone fruit crop management practices at the beginning (2009) and end (2012) of the project. There were significant changes in pest management practices as a result of this project. The most dramatic change was the increased usage of pheromone mating disruption for peachtree borers as an alternative to insecticidal treatments. Stone Fruit IPM information was also disseminated through 11 presentations at state and regional meetings attended by over 800 people and two poster presentations seen by over 1,000 people. Outreach on stone fruit IPM was also provided through Fruit IPM updates via Email to over 190 growers.

Introduction:

Stone fruits (peaches, nectarines, plums, apricots, cherries) are usually grown in New England as part of diversified orchard operations. Grown on more than a thousand acres throughout New England, with approximately half of that in Connecticut, stone fruits are a very high-value crop, as they are produced primarily for the fresh market, mostly sold at farm stands, farmer’s markets and local stores. Apple pest management in New England enjoys many strategies, due to the tremendous amount of research done on this crop. By contrast, precise pest management guidelines are lacking for stone fruits in New England; what little there is focuses primarily on pesticide selection and use. However, most New England orchardists, already familiar with Integrated Pest Management (IPM) practices for apples, should be able to easily adopt new IPM methods for stone fruits. In a preliminary e-mail survey (2008), Connecticut growers identified the top three stone fruit diseases as bacterial spot, brown rot and peach leaf curl, and the top three insect pests as the plant bug complex (tarnished plant bug, oak and hickory plant bugs), borers (greater peach-tree borer, lesser peach-tree borer) and plum curculio. This conforms to the results of a 2002 survey, which showed that the majority of peach acreage in New England was treated for these three pests (88% for plant bugs; 91% for plum curculio and 74% for peach tree borers). The goal of this project was to assist New England stone fruit growers in moving toward an environmentally friendly, sustainable and more reliable stone fruit production. The project consisted of two parts: an outreach and a research component. The outreach component focused on increasing awareness and disseminating knowledge on currently available sustainable management practices of major stone fruit insects and diseases. This was done primarily with educational print materials, talks at grower meetings, field demonstrations and on-site training on scouting, pest identification, and best management practices. The research component was aimed at the development of a biological control for bacterial spot, utilizing bacterial viruses, known as phages, which are naturally associated with the bacterium. The research component tested two additional biocontrol treatments against the standard treatment of dormant copper and an antibiotic.

Performance Target:
Research Component

The original objectives of this project were to develop an effective bacteriophage-based biological control strategy for controlling peach bacterial spot, which would provide an environmentally friendly and feasible alternative to the current chemical-based strategies. An additional objective was to compare the phage-based method to current copper and antibiotic based methods. However, the absence of genetic diversity among naturally occurring phage populations, and the inability to produce BLS symptoms in a controlled greenhouse setting, have resulted in the decision to revise the objectives to abandon further phage experiments, and to incorporate a randomized orchard trial of the most commonly used copper and antibiotic based control strategies. Additional target is a publication of the results of this project in a peer-reviewed scientific journal. Due to results insufficient for publication, this target was not reached.

Outreach Component

20 Connecticut stone fruit producers will adopt biologically-based integrated management techniques on 200 acres, such as mating disruption of peach tree borers, using traps and groundcover management to monitor and reduce tarnished plant bug populations, and better timing of insecticide and fungicide applications. In addition, they will substitute newer, less toxic, pesticides for some of the organophosphate and pyrethroid insecticides.

Cooperators

Click linked name(s) to expand
  • Robert Durgy

Research

Materials and methods:
Research Component

The goal was to develop a biological control method against bacterial spot using natural enemies of the pathogen, called bacteriophages or phages (viruses that attack bacteria). Bacterial spot of stone fruits is caused by the plant pathogenic bacterium Xanthomonas arboricola pv. pruni (Xap). Phages naturally associated with this bacterium were to be used to protect plants from infection and reduce the severity of the disease. The research strategy had four parts: (1) collect strains (individual pure cultures) of Xap, as well as phages from a large number of diseased plant samples; (2) test antibacterial efficacy of phages in laboratory and bioassays; (3) conduct disease control trials in the greenhouse to evaluate the effectiveness of phages for preventing disease (used alone or in combination with chemicals or with other biological control agents) and, (4) evaluate the most effective treatments in orchard trials. Part 1 – Collecting Xap and phages. We collected peach, nectarine, apricot and plum leaves and fruits, which showed symptoms of bacterial spot, from farms in Connecticut and Massachusetts. Xap was isolated from these samples at the CAES Plant Pathology laboratory, in New Haven, CT. These tissues were also assayed for the presence of bacteriophages; any identified phages were isolated. Approximately 150 plant samples were collected from 50 locations around the state, with the goal of obtaining approximately 100 Xap strains and 40 phages. Part 2 – Testing phages in laboratory and in bioassays. The collected phages were tested against the collected Xap strains in order to establish a host range for the phages and get an overall picture of diversity. The phages would be grouped according to this host range information and other cultural characteristics. Representatives from each phage group were to be evaluated for their antibacterial efficacy both in laboratory tests and in bioassays on peach seedlings. Part 3 – Greenhouse trials. These trials were conducted in CAES greenhouses in New Haven, CT. Assuming phage diversity, five to six of the most effective phages from the bioassays would be applied together for maximum effect. The phage treatments would then be evaluated alone and in combination with chemical antibacterials [Kocide, (copper-hydroxide), Mycoshield, (oxytetracycline) and with biological control agents [Serenade ASO, (Bacillus subtilis) and Blight Ban A506 (Pseudomonas fluorescens)], according to the treatment list (shown). Peach seedlings of the highly susceptible variety, O’Henry, grown in pots in the greenhouse, were to be subjected to the above mentioned treatments, five plants per treatment, and then sprayed with Xap to induce disease. The untreated control plants would be inoculated with Xap, but receive no treatment against the disease. After inoculation with the bacterium, the plants were to be kept in a humidity chamber for 1 day to help disease development and then arranged on a greenhouse bench in a randomized complete block design. Three to four weeks later, upon the appearance of leaf spots consistent with BLS, the spots would be counted on each plant, the data then subjected to statistical analysis (analysis of variance and subsequent separation of sample means by the Waller-Duncan K-ratio t test) to determine if there were significant differences in effectiveness among the treatments. The experiment were to be repeated three times. Part 4 – Orchard trials. Three experimental peach orchards, using the highly susceptible variety Sweet Dream on Lovell rootstock, were established at three CAES research farms (Hamden, Windsor and Griswold). Each orchard was planted in a 7×7 design, as shown below. In their third year, the orchards would be used to test the two most promising treatments determined in Part 4 greenhouse trials, as compared with the currently recommended management plan (dormant copper spray plus Mycoshield during the growing season). The Latin Square experimental design was used, with three experimental treatments (two of which were untreated controls) and five plants per treatment. Sprays were applied at 10% bloom and repeated every 7-10 days for up to 6 sprays using a hand-held sprayer. Treatments were applied in 100gal water/A and sprayed till run-off. Disease severity for bacterial spot was assessed on 9, 12 and 15 September 2013, for Griswold, Hamden, and Windsor, respectively. Disease was based on the scale where 1 = no disease, 2 = less than 10% of the leaves showing spots, 3 = 11-50% of the leaves showing spots, 4 = 51-75% of the leaves showing spots, and 5 = more that 76% of the leaves with spots. Data were subjected to a Kruskal-Wallace test at P = 0.05.

Outreach Component

During each year of the project, stone fruit IPM information was provided to growers in a variety of ways. The most intensive type was onsite training in the growers’ own orchards throughout the growing season.   Six growers in 2009 and 2010 and 7 growers in 2011 received field training. A total of 13 growers with 69 acres were involved in one-on-one training from 2009 through 2011. Most were involved for multiple years.

Training included use of mating disruption and monitoring traps for peachtree borer, lesser peachtree borer and Oriental fruit moth; identification of diseases such as bacterial spot, peach scab, brown rot and X-Disease; identification of damage caused by Oriental fruit moth, borers, European red mites and tarnished plant bug; identification of chokecherries to aid in X-Disease management; and management options for all of the above pests. In 2012 and 2013, education and surveys were conducted for spotted wing drosophila and brown marmorated stink bug, two new invasive pests of stone fruits.

In addition three growers with 85 acres of stone fruits participated in the Eco Stone Fruit project beginning in 2010 by following IPM protocols which were developed by the Co-PI and others through Red Tomato http://redtomato.org/ecopeach.php. Red Tomato is a nonprofit organization which helps farmers sell their sustainably grown produce to supermarkets, distributors and other buyers. As a result, a total of 16 Connecticut growers with 154 acres were directly involved with the UConn IPM program through this SARE project. A range of farms was represented from a small organic CSA farm to the largest commercial retail and wholesale orchards in the state.

Information was also disseminated via talks at grower meetings, field demonstrations and educational printed materials.

 

Research results and discussion:
Research Component

MILESTONE 1: Isolate 40 bacteriophages from New England stone-fruit orchards. Progress: Twenty-three Xap isolates and 43 phage isolates were obtained in the spring and summer of 2009 from a total of 19 orchards: two from New York, one from Massachusetts, and the remainder in Connecticut. MILESTONE 2: Ten phages that show potential as biological control agents based on preliminary laboratory tests will be evaluated in bioassays. Progress: Each of the 43 phage isolate was tested against each of the 23 Xap strains. Contrary to expectation, we found that all 43 phage isolates were infective on all 23 Xap strains. Furthermore, immunity conferred by one phage through lysogenicity resulted in immunity to all 42 others, and this was true for all 23 Xap strains. When this experiment was repeated, we observed identical results. An important conclusion from this result was that it precluded having the mixture of genetically variable phage strains, on which this research was predicated, to use in the bioassays, greenhouse, and orchard trials. Further tests to identify any differences in virulence specificity among the phage strains confirmed these results, i.e., that all 43 phage strains are functionally equivalent in terms of their specificity to Xap strains. MILESTONE 3: Five phages that show potential based on bioassays will be mixed together and used in subsequent greenhouse trials. Progress: Further work with the bacteriophage was abandoned due to results from Milestone-2. Sixty small O’Henry peach trees (O’Henry has very high susceptibility to Xap), were purchased and maintained in the greenhouse, and used in 2010 and 2011 for purpose of testing efficacy of biocontrol strategies in controlling BLS. Attempts in both years to infect individual trees or detached branches (there are no reports of this method being used in the scientific literature) with various Xap strains proved unsuccessful, regardless of efforts to maximize favorability of conditions. The reasons for failure are unknown, but corroborate anecdotal information from veteran researchers in this field, that BLS symptoms are difficult to reliably replicate in either the greenhouse or the field. Unable to reliably and reproducibly effect infections, these efforts have been abandoned. MILESTONE 4: Three phage-based treatments (phage mixture alone or together with other biological control agents) that provide equal or superior disease suppression compared to the currently used copper/antibiotic-based control methods in greenhouse trials will be chosen for further trials in Milestone 5. Progress: None; see “progress” discussions in Milestones 2 and 3. Therefore, the phage-based treatments could not be incorporated into the 2013 biocontrol trials. MILESTONE 5: Two phage-based treatments that provide equal or superior disease suppression compared to the currently used copper/antibiotic-based control methods in orchard trials will be tested in orchard settings. Progress: Three orchards, each planted in April 2010 in a 7×7 pattern with 49 Sweet Dream (high BLS susceptibility) peach trees on Lovell rootstock, were maintained each year with spring and mid-summer pruning. As explained in Milestones 1-4, the development of phage-based treatments failed, and therefore none were used in 2013 orchard trials. However, the orchards were used to compare the standard recommendation of dormant copper and Mycoshield to two experimental biocontrol methods, Serenade ASP (Bacillus subtilis), and Blight Ban A506 (Pseudomonas fluorescens). Disease pressure was negligible in Windsor and Griswold,so no data are presented. Slight disease pressure was observed in Hamden. A disease rating of 2.07 was observed for the control with the standard recommendation of dormant copper and Mycoshield generating a disease rating of 1.0 (no disease). Serenade ASP produced a mean disease ratings of 1.4, and Blight Ban A506 produced a 2.0 disease rating. These results cannot be used to make any conclusions regarding the efficacy of the treatments. Because the development of BLS depends on suitable environmental conditions, there are no assurances that experiments such as this can be reliably performed in a single season. Therefore, repeating these experiments for multiple seasons would be necessary in order to judge whether any of these treatments is efficacious in preventing development of the disease.

Outreach Component

MILESTONE 1 (90 Connecticut growers will assess their baseline practices via survey).
A survey was developed to assess the baseline of stone fruit crop management practices including major insect and disease pests and pest management strategies used. The original mailing was sent in June, 2009 to 124 people on the University of Connecticut IPM orchard mailing list. The mailing included the survey and information on the bacterial spot/bacteriophage research from the research component of this grant. It also included a request for growers to participate by having their stone fruit sampled for bacterial spot as part of the research project. Reminder notices for survey responses were also sent in August and October, 2009. A total of 96 responses were received; a 77% response rate. A total of 45 surveys were completed and returned. The remaining 51 responses reflected those operations that were no longer in business; did not grow peaches; or were backyard growers. A follow up survey with the same questions was sent in October 2012 to 67 growers on the stone fruit mailing list which was updated after the initial survey. Reminder notices for survey responses were also sent in December 2012 and January, 2013. A total of 44 responses were received; a 66% response rate. 40 of the surveys were usable. The remaining 4 surveys reflected those out of business or backyard growers. Comparisons between baseline and post project surveys are summarized in the Impact section of this report.The project proposal projected that 90 Connecticut stone fruit growers would participate in the survey. This was based on an estimate of stone fruit growers from the Connecticut Department of Agriculture. We updated our mailing list based on our survey returns and found that there are only approximately 60 stone fruit growers in Connecticut.

MILESTONE 2 (90 Connecticut growers will receive a manual outlining IPM techniques and sustainable practices for stone fruit production).
A publication entitled “IPM Guidelines for Insects and Diseases of Stone Fruits” by Lorraine Los and Mary Concklin, which outlines IPM techniques and sustainable practices for stone fruits, was completed. It was mailed to all Connecticut stone fruit growers in December 2013.   It is also posted on the UConn IPM website www.ipm.uconn.edu so that growers and Extension personnel in other states can easily access the information. The online version also provides live links to additional information and photos of each pest. 

MILESTONE 3 (Six growers will receive one-on-one training to help identify pests and learn about conventional and alternative methods of managing pests).
The one-on-one grower training visits were primarily conducted during 2009, 2010 and 2011. Six growers in 2009 and 2010 and 7 growers in 2011 received field training; most for multiple years. A total of 13 growers with 69 acres were involved in one-on-one training. Training included use of mating disruption and monitoring traps for peachtree borer, lesser peachtree borer and Oriental fruit moth; identification of diseases such as bacterial spot, peach scab, brown rot and X-Disease; identification of damage caused by Oriental fruit moth, borers, European red mites and tarnished plant bug; identification of chokecherries to aid in X-Disease management; and management options for all of the above pests. In addition, intensive sampling for peachtree borer infestations was conducted to determine the effectiveness of mating disruption. In 2012 and 2013, education and surveys were conducted for spotted wing drosophila and brown marmorated stink bug, two new invasive pests of stone fruits.
Three additional growers with 85 acres of stone fruit participated in the Eco Stone Fruit project by following IPM protocols which were developed by the Co-PI and others through Red Tomato beginning in 2010. As a result, a total of 16 Connecticut stone fruit growers with 154 acres were directly involved with stone fruit IPM through this SARE project. A range of farms were represented from a small organic CSA farm to the largest commercial retail and wholesale orchards in the state.

MILESTONE 4 (New stone fruit management guidelines and phage research will be discussed at the annual meetings of the Connecticut Pomological Society). The following four presentations and one poster display were made during this project.

  • Los, L. 2009. Development of Stone Fruit IPM Guidelines in the Northeast. Annual Meeting of the CT Pomological Society. December 2, 2009. 60 attendees.
  • Marra, R. 2009. Bacterial Spot and Bacteriophages in Stone Fruits. Annual Meeting of the CT Pomological Society. December 2, 2009. 60 attendees.
  • Marra, R. 2010. Update on Peach Bacterial Spot. Annual Meeting of the CT Pomological Society. December 1, 2010. 75 attendees.
  • Los, L. 2011. Management of the Brown Marmorated Stink Bug, a New Invasive Pest of Stone Fruits. Annual Meeting of the CT Pomological Society.       December 6, 2011. 90 attendees.
  • Los, L. and M. Concklin. 2012. Stone Fruit IPM. Five posters were developed and displayed. Annual Meeting of the Connecticut Pomological Society. December 4, 2012. 88 growers were in attendance.

MILESTONE 5 (40 Growers will attend twilight meetings on stone fruit IPM guidelines). The following twilight meetings included stone fruit IPM information.

  • Los, L. 2009. Use of Mating Disruption for Peachtree Borers. Connecticut Pomological Society Twilight Meeting. April 28, 2009. 15 attendees. A handout was provided to explain the details for this management technique.      
  • Los, L. 2009. Identification of Chokecherry, a Wild Host of X-Disease of Stone Fruits. Connecticut Pomological Society Twilight Meeting. June 10, 2009. 40 attendees.
  • Los, L. 2010. Use of Mating Disruption for Peachtree Borers. Connecticut Pomological Society Twilight Meeting. May 25, 2010. 80 attendees. The host orchard used mating disruption in 2010. A handout was provided to explain the details for this management technique.
  • Los, L. 2010. Stone Fruit IPM Techniques. Connecticut Pomological Society Twilight Meeting. June 15, 2010. 75 attendees. The host orchard participated in the Eco Stone Fruit project through Red Tomato.
  • Los, L. 2011. Monitoring for the Brown Marmorated Stink Bug. Connecticut Pomological Society Twilight Meeting. July 14, 2011. 80 attendees.

MILESTONE 6 (Stone fruit IPM techniques will be discussed at Plant Science Day).

A poster on the peach bacterial spot research was presented at Plant Science Day of the Connecticut Agricultural Experiment Station in August, 2009 which was attended by over 1,000 people.

MILESTONE 7 (Growers from the New England states will learn about the Stone Fruit management guidelines at the New England Vegetable and Fruit Conference in Manchester, NH). The following presentations were made at this conference.

  • Los, L. 2011. Development of Stone Fruit IPM Guidelines for the Northeast. New England Vegetable and Fruit Conference and Trade Show. Manchester, NH. December 13, 2011. 110 attendees.
  • Concklin, M. 2013. Description of an IPM Program for Peaches. New England Vegetable and Fruit Conference and Trade Show.       Manchester, NH. December 17, 2013. 100 attendees.

 

 

Participation Summary

Education

Educational approach:
Research Component

No publications have resulted from this work, due to the failures as described above. The results of the phage experiments were shared with the Connecticut Pomological Society at their winter meeting in 2010.

Outreach Component

Milestones 2 through 7 describe the primary outreach of this project. Additional outreach, not included in initial grant proposal, included:

  • Botond Balogh and Lorraine Los met with Dan Cooley (University of Massachusetts Plant Pathologist) and Jon Clements (University of Massachusetts Tree Fruit Extension Specialist) at the University of Massachusetts Orchard in Belchertown, MA on July 23, 2009. This visit was initiated by Lorraine Los so that colleagues in Massachusetts were aware of this SARE project and stone fruit IPM. The orchard was surveyed for bacterial spot, peachtree borers and other stone fruit pests. Two commercial orchards in Massachusetts were also visited by the group and sampling was conducted for the bacterial spot/bacteriophage research. A survey for chokecherries (host of X-Disease) was also conducted at each site. Jon Clements wrote an article posted on the UMass Fruit Advisor website which described the stone fruit pests and IPM techniques discussed during our visit. See http://jmcextman.blogspot.com/2009_07_19_archive.html. Connecticut and Massachusetts represent the largest stone fruit acreage in the New England states.
  • Lorraine Los met with Connecticut stone fruit growers and Red Tomato personnel at the 2009 New England Vegetable and Fruit Conference in Manchester, New Hampshire on December 16, 2009. Red Tomato is a nonprofit organization which helps farmers sell their sustainably grown produce to supermarkets, distributors and other buyers. The purpose was to discuss the feasibility of an Eco-Peach project with Red Tomato. Lorraine agreed to be involved as one of the lead scientists to develop the IPM protocols for Eco-Peach. This fit in nicely with the goals of this SARE project. A draft set of guidelines for Eco-Peach was developed in February, 2010. Lorraine was also involved with the revisions of the Eco-Stone Fruit Guidelines in 2011 and 2012. Three Connecticut stone fruit growers are certified Eco-Stone Fruit growers. http://redtomato.org/ecopeach.php
  • Lorraine Los was the editor of the stone fruit sections of the 2010, 2011, 2012 and 2013 editions of the New England Tree Fruit Management Guide. All pesticide recommendations and IPM information were reviewed and revised.       New pesticides which are alternatives to organophosphate and pyrethroid insecticides were added whenever possible. http://extension.umass.edu/fruitadvisor/sites/fruitadvisor/files/publications/pdf/2013NewEnglandTreeFruit.pdf
  • Outreach was also provided through Fruit IPM updates throughout the growing season via Email to over 190 growers.   Approximately 20 Email updates per year included information on stone fruit IPM.

Additional Project Outcomes

Project outcomes:

Impacts of Results/Outcomes

Research Component

Despite a broad collection of 43 phage strains that were collected from stone fruit orchards in Connecticut, Massachusetts, and eastern New York, no genetic diversity was observed in terms of bacterial host specificity or host resistance, and this was true for all 23 Xap isolates used in this study. Based on these results, we were forced to abandon any hope of developing a phage-based biocontrol strategy for BLS; in the absence of phage diversity, bacterial strains would quickly become lysogenic–resistant–to the single phage genotype. This strategy has worked for other bacterial plant diseases, such as bacterial soft, fire blight, citrus canker, and bacterial spot of tomato, but in all these instances, phage diversity was demonstrated as a precondition to developing phage mixtures for biocontrol experiments. Our efforts to produce BLS symptoms, which failed in 2010 using whole trees in greenhouses, were attempted again in 2011 using detached branches in flasks of water in growth chambers, to allow for better regulation of conditions supportive of infection. These efforts were not successful, and were therefore abandoned. It is possible that our rudimentary greenhouse, which cannot adjust humidity or temperatures below ambient, was insufficient for these types of experiments. Three peach tree orchards that were planted in spring of 2010, each in a 7 x 7 arrangement, were maintained with early spring and mid-summer pruning and the replacement of any dead trees. These orchards were originally intended for use in orchard trials in spring/summer 2013 that would compare phage against, and in combination with, two other methods, which would be chosen based on results of greenhouse/growth chamber trials. However, due to the inability to produce BLS symptoms in greenhouse settings, and the absence of phage diversity, there were no data from preliminary greenhouse trials to use in determining the 2013 field research. Therefore, we conducted randomized trials using the current standard biocontrol strategy of dormant copper and Mycoshield (oxytetracycline) compared to two experimental methods, Serenade ASO (Bacillus subtilis) and Blight Ban A506 (Pseudomonas fluorescens). Results from these experiments were mixed, and inconclusive.

Outreach Component

The main components of the Verification Plan were the grower surveys conducted in 2009 and 2012, at the beginning and end of the grant, to determine the growers’ knowledge and implementation of stone fruit IPM practices (see Milestone 1).

A key component of IPM is the identification of pests and their damage. The surveys conducted in 2012 indicated an increase in grower recognition of plant bug injury, adult tarnished plant bugs, peachtree borer injury, lesser peachtree borer injury, Oriental fruit moth damage, and bacterial spot injury. Another critical component of IPM is accurate pest monitoring. The 2012 survey also showed that the percentage of growers who conducted monitoring increased for plant bugs, pheromone trapping for lesser peachtree borer, peachtree borer, and Oriental fruit moth. Growers also reported a decrease in pesticides by an average of 1.5 treatments per year. Specific reductions were noted for plant bugs (25% of growers), peachtree borers (41% of growers), mites (26% of growers), Oriental fruit moth (6% of growers), and Japanese beetles (78% of growers). Growers also learned that brown rot fungicide sprays are most critical at bloom and again starting 3 weeks before harvest. As a result, growers reported a decrease in fungicide sprays during the non-critical mid-season timing. In 2012, 40% of growers reported that they spray brown rot fungicides only during targeted timing as compared to only 15% in 2009. Forty percent of growers also indicated that they had increased sanitation for brown rot by pruning out sources of disease inoclum.

The most dramatic change in IPM practices was the use of pheromone mating disruption for peachtree borer and lesser peachtree borer. Twenty growers (210 acres) reporting using mating disruption in 2012 as compared to only 5 growers (47 acres) in 2009. Because most of the larger growers are using mating disruption, 77% of the acreage of surveyed growers had been treated with mating disruption in 2012. Mating disruption for peachtree borers is replacing the use of trunk sprays of chlorpyrifos or pyrethroid pesticides. The use of mating disruption for Oriental fruit moth also increased. In 2012, 5 growers with 47 acres of stone fruits used mating disruption for Oriental fruit moth as compared to no reported usage in 2009. In addition to the changes in quantity of pesticide; growers also indicated a change in types of pesticides used. Twenty five percent of the 2012 surveyed growers indicated that they changed pesticides to minimize the effect on orchard beneficials; predominantly by reducing the amount of pyrethroids whenever possible.   Growers also reported reductions in organophosphate insecticides whenever possible.

The Connecticut stone fruit growers benefited considerably from this project because they learned to better identify pests and their damage, improved their pest monitoring techniques, improved timing of pesticide applications, reduced the use of pesticides, changed the types of pesticides used in order to help conserve beneficials, and reduced a known high leaching pesticide (chlopyrifos) by using mating disruption for peachtree borers. Our surveys were conducted with Connecticut growers. However, it is expected that the growers from other states that attended two presentations at the New England Vegetable and Fruit Conference in Manchester, NH also learned (see Milestone 7) about stone fruit IPM. The general population benefited from this project by being able to enjoy stone fruits grown in a more sustainable manner.

Economic Analysis

Research Component

Nothing to report

Outreach Component

Based on survey responses discussed in the previous section, growers reported a reduction in the amount and type of pesticides used between the beginning and end of this SARE outreach project. However, an economic analysis of pesticide programs for each grower surveyed was beyond the scope of this project.

In addition, an offshoot of this project was the Co-Pi’s involvement in the development of Eco-Stone Fruit protocols through Red Tomato. Growers certified in this program have another market niche to sell their fruit. Currently, three of the largest Connecticut stone fruit growers are certified in the Red Tomato Eco-Stone Fruit program.

 

Farmer Adoption

Research Component

Nothing to report (Not applicable)

Outreach Component

See Impact section above.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

Research Component

No further study warranted.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.