Development and on-farm training of biologically based methods for integrated crop management of stone fruits in New England
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. Bioassays were attempted in the greenhouse in March-April of 2010, but failed due to inability to infect trees under greenhouse conditions that exceeded the range of those acceptable for bacterial infection. All trees are now undergoing a 750-hour chill period in preparation for forcing in February 2011, after which branches will be tested in detached branch bioassays in the growth chamber, where conditions can be more accurately controlled. Assuming we are able to effect infections, we will then test the bacteriophage/bacterium interaction in vivo.
Eleven Connecticut growers with 113 acres of stone fruits received one-on-one training in IPM practices in 2010. All 11 growers adopted at least one new practice, specifically the use of mating disruption for peachtree borer and lesser peachtree borer. The use of mating disruption alone resulted in the reduction of 678 pounds of active ingredient of chlorpyrifos, which is typically applied on a yearly basis for borer control. Twenty-five Connecticut stakeholders learned about this project at the CAES open house in August. Seventy five growers learned about the bacterial spot research at the Annual Meeting of the Connecticut Pomological Society in December, 2010. In addition, growers learned about specific stone fruit IPM methods at two summer twilight meetings with a total of 155 people in attendance.
Develop 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. Additional target is a publication of the results of this project in a peer-reviewed scientific journal.
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 fungicide and bactericide applications. This will result in savings of 2,000 pounds pesticide a.i. and $25,000 on production cost each year. In addition, they will substitute newer, less toxic, pesticides for some of the organophosphate and pyrethroid insecticides.
MILESTONE 1 (Isolate 40 bacteriophages from New England stone-fruit orchards). Progress: 43 phages were isolated 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. Each phage was tested against the 23 Xap strains. Additionally, we have demonstrated that all 43 phages behave identically, and that phage immunity conferred through lysogenicity with one phage strain constitutes immunity to all 42 others. This experiment was repeated. An important conclusion from this result is that we will not have a mixture of genetically variable phage strains to use in the bioassays, greenhouse, and orchard trials.
MILESTONE 2 (Ten phages that show potential as biological control agents based on preliminary laboratory tests will be evaluated in bioassays).
Progress: Further tests to identify any differences in virulence specificity among the phage strains confirmed the original hypothesis that all 43 phage strains are functionally equivalent in terms of their ability to infect Xap strains.
MILESTONE 3 (Five phages that show potential based on bioassays will be mixed together and used in subsequent greenhouse trials). Progress: Sixty small O’Henry peach trees (O’Henry has very high susceptibility to Xap) were potted up and forced in the greenhouse in February/March of 2010. Attempts to infect individual trees with various Xap strains proved unsuccessful. This failure is attributable to the difficulty we are having in finding greenhouse space with conditions that can support infection.
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). Progress: Greenhouse bioassays will be tested in growth chambers in March-April of 2011 on detached branches of O’Henry greenhouse trees, referenced in Milestone 3 above.
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 recognized as environmentally friendly alternatives). Progress: 160 Sweet Dream peach trees on Lovell rootstock were planted in April 2010 in three Connecticut orchards. Bioassay trials will be performed spring 2012.
MILESTONE 2 (90 Connecticut growers will receive a manual outlining IPM techniques and sustainable practices for stone fruit production).
Progress: A manual of IPM techniques and sustainable practices for stone fruit is under development. It will be produced and distributed to stone fruit growers in 2011.
MILESTONE 3 (Six growers will receive one-on-one training to help identify pests and learn about conventional and alternative methods of managing pests).
Progress: A total of eleven Connecticut growers with 113 acres of stone fruits were involved with IPM programs in 2010. Six growers with 28 acres of stone fruits received one-on-one field training throughout the 2010 season. Training included use of mating disruption for peachtree borer and lesser peachtree borer, use of pheromone traps for both borers 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. Three additional growers with a total of 30 acres of stone fruits received training on the use of mating disruption and trap monitoring for peachtree borers and lesser peachtree borers. Two additional Connecticut growers with 55 acres of stone fruit participated in the Eco Stone Fruit pilot project by following IPM protocols which were developed by the Co-PI and others through Red Tomato. A range of farms was represented including one organic CSA (Community Supported Agriculture) farm.
MILESTONE 4 (New stone fruit management guidelines and phage research will be discussed at the annual meetings of the Connecticut Pomological Society).
Progress: Robert Marra presented Update on Peach Bacterial Spot Research at the Annual Meeting of the Connecticut Pomological Society on December 1, 2010. 75 growers were in attendance.
MILESTONE 5 (40 Growers will attend a twilight meeting where new stone fruit IPM guidelines will be demonstrated).
Progress: Eighty people growers attended an orchard twilight meeting on May 25, 2010 and learned about the use of mating disruption for peachtree borer and lesser peachtree borer. A handout was provided to explain the details for this management technique. The host orchard used mating disruption in 2010. Seventy five people attended a twilight meeting on June 15, 2010 and learned about mating disruption of peachtree borers; Oriental fruit moth life cycles, monitoring and control by mating disruption; and alternatives to pyrethroid insecticides for cat-facing insects such as plant bugs and stink bugs. This twilight meeting was held at an orchard participating in the pilot program of the Eco Stone Fruit project through Red Tomato.
MILESTONE 7 (200 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)
Progress: Lorraine Los contacted the organizers of this conference and offered to give a presentation at the meeting being held in December, 2011.
Impacts and Contributions/Outcomes
Forty-three phage strains have been obtained from stone fruit orchards in Connecticut, Massachusetts, and eastern New York. These are equally virulent on all 23 of the Xap isolates that were collected from the same distribution of orchards. Therefore, we are making progress towards our goal of developing a phage-based biological control strategy for controlling bacterial spot of stone fruit. Bioassays that failed last year will be tested this spring in growth chambers using branches maintained in flasks of water, to allow for better regulation of conditions supportive of infection. Three orchards of peach trees were planted this past spring (2010), each in a 7 x 7 arrangement, to be used in orchard trials in spring/summer 2012, comparing phage against and in combination with two other methods, which will be chosen based on results of greenhouse/growth chamber trials. Once results are obtained from these experiments, we will publish the results and conclusions in a peer-reviewed journal, such as Phytopathology.
Nine Connecticut growers with 58 acres of stone fruit participated in one-on-one training in IPM techniques in 2010. Two additional growers with 55 acres participated in the pilot Eco Stone Fruit project. All of the growers used mating disruption for peachtree borers and lesser peachtree borers. The use of mating disruption alone resulted in a decrease of 678 pounds of pesticide active ingredient of chlorpyrifos, an organophophate. The changes in pesticide applications due to the use of other IPM practices still need to be determined. In addition, the pesticide use changes for all other growers (those not involved in one-on-one training) will not be known until the post-project survey is conducted in 2012.
Other accomplishments not related to original milestones:
Lorraine Los was one of the lead scientists in the development of the IPM protocols of the Eco Stone Fruit project through Red Tomato. Red Tomato is a non profit organization which helps farmers sell their sustainably grown produce to supermarkets, distributors and other buyers. Protocols were developed and were discussed at the Red Tomato Grower meeting on March 11, 2010. Two Connecticut growers and one New York grower participated in the pilot program during the 2010 season.
Research Farm Manager
The Connecticut Agricultural Experiment Station
190 Sheldon Road
Griswold Research Center
Griswold, CT 06351-3627
Office Phone: 8603760365