Performing Department
PLANT SOIL MICROBIAL
Non Technical Summary
Organic tree fruit production (apples, cherries, peaches)east of the Mississippi river will not be sustainable without effective management of the bacterial diseases fire blight, bacterial canker, and bacterial spot. Bacteriophages (phages) represent a promising tool for the management of bacterial plant diseases; however, phages have not been developed commercially mainly due to reduced and inconsistent efficacy. We intend to intensively investigate the phage:pathogen dynamics on apple and cherry flowers withErwinia amylovora(fire blight, apple)Pseudomonas syringae(bacterial canker, cherry). We predict that the increased precision in understanding these systems will enable us to more effectively and efficiently employ phages in organic orchards. We will also investigate materials that can disrupt cellular aggregates on plant surfaces, and mixing-partner materials that can weaken or kill a subset of target cells to aid in increasing the efficacy and reliability of phages. We will conduct yearly field testing of promising materials on apple, cherry, and peach. Extension activities will include developing a biopesticide selection tool for the three tree fruit diseases studied, producing a video to demonstrate the mode of action of phages, and reporting project findings to growers at through local and regional fruit schools, webinars, and field days.
Animal Health Component
0%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The overarching goal of this project is to address critical knowledge gaps that have so far prevented phage biocontrol deployment for management of bacterial diseases of tree fruits. Goals of the project are to use a frequent sampling approach combining genetic and culture-based techniques to simultaneously track the population dynamics of bacterial pathogens and phages during the flower colonization cycle to better understand phage activity in biocontrol applications to inform better deployment tactics. A second goal is to identify surfactants or other compounds that can disrupt bacterial aggregates and better enable phages to contact bacterial cell targets. A third goal is to combine phages with other materials that can slow the growth of bacterial plant pathogens to better enable phages to contact, attach to, and infect to enable successful biocontrol.
Project Methods
We will utilize microbiological culture-based techniques along with quantitative realtime PCR to track the population dynamics of bacterial pathogens and phage on flowers (apple, cherry) and leaves (peach). In addition, we will use frequent sampling to better track dynamics to understand how phages are operating under field conditions. We will inoculate pathogens and phages at different timings and in differentproportions to better approximate how these processes might be operating in commercial orchards.We will test a variety of surfactants and other compounds for their ability to disrupt bacterial aggregates. The experiments will first be conducted in vitro in 96-well plates where we will first enable aggregates to form prior to adding in test compounds. Following the addition of the test compounds, we will evaluate phage ability to kill treated cells and if this is increased or decreased compared to controls. Compounds that increase phage activity in replicated expeirments will then be tested in field conditions.We will test compounds such as contact sterilants and coppers used at lower rates, and we will also test the impact of reductions in pH in an attempt to reduce pathogen growth to give time for phages to attach to, infect, and kill these cells. These experiments will inititally be conducted in vitro which will also enable us to assess the compatibility of phages with the various compounds. Best performing materials will be tested in the field.We will develop extension programs to educate and engage growers in best practices for using phages for biocontrol. This work will include developing a biopesticide information and selection tool and an educational video summarizing what phage are and how they work for biocontrol.