Progress report for SW22-939
Project Information
Washington State provides nearly all organic pome fruit grown in the USA with an estimated annual farm gate value of a half billion dollars. There are currently 31,000 certified organic acres of pome fruit in the state and it is expected to reach 38,000 by 2021. The dry climate of central WA during the growing season may not be always conducive to orchard diseases, but many pathogens can cause latent infections and result in decays once conditions become more favorable in storage. This limits the packers’ ability to store organic apples more than four months, after which losses to postharvest decays, topping 30%, become economically unsustainable. Beside sanitation, there are no effective organic control strategies currently. Producers suffer from a lack of knowledge about the efficacy of the few existing bio-fungicides, lack of more effective organic materials and knowledge about appropriate sprays and timing. Once organic apples are harvested, packers are limited to room, bin, and flume water sanitation to mitigate postharvest diseases, but often these strategies become ineffective after two months. Therefore, we propose to 1) evaluate organic materials (biological agents, plant extracts, GRAS) and develop a timely spay program, 2) collaborate with producers to test effective materials at commercial orchards in three main production regions to ensure efficacy under various conditions, and 3) evaluate the efficacy of dynamic controlled atmosphere to store organic fruit and curb decay. Economic analyses will evaluate the impact of the proposed management tactics on producers. Outreach activities will include field and warehouse days at producer sites, talks at state and regional commodity meetings, and the production of educational materials. This project will render the production and storage of organic tree fruit more sustainable to meet the increasing demand for safer produces and strengthen the competitiveness and the economy of the western region.
OBJECTIVE 1: Evaluate the efficacy of existing and new organic materials and develop a timely preharvest spray program (Research). 1) Evaluate the efficacy of organic materials applied preharvest against major pathogens causing postharvest diseases and on detached fruit, 2) develop a timely preharvest spray program to optimize management of postharvest decays.
OBJECTIVE 2: Evaluate enhanced management tactics in commercial orchards located in different productions regions of central Washington (Research). 1) Evaluate the efficacy of selected spray programs, at three commercial orchards in collaboration with our three collaborator producers, to control storage decays over short and extended storage periods. 2) Assess the economic impact (benefits/costs) of suggested new spray programs.
OBJECTIVE 3: Assess the efficacy of dynamic controlled atmosphere (DCA) to control or reduce infections of major postharvest pathogens (Research). 1) Evaluate the efficacy of DCA against four major postharvest pathogens on inoculated fruit in controlled and commercial conditions. 2) Assess the economic impact (benefits/costs) of DCA.
OBJECTIVE 4: Conduct a vigorous education and outreach program with input from our producer cooperators. Create and disseminate extension materials to growers and packers in the PNW and me measure improve in knowledge acquired by stakeholders and change in practices regarding organic disease management.
Cooperators
- - Producer
- - Producer (Researcher)
- - Technical Advisor (Researcher)
- - Producer
Research
Objective 1. Evaluate the adequacy and efficacy of current and novel preharvest management organic strategies (Year 1-2). Activity 1.1. Efficacy of existing and potential new products in the orchard: In a first step, we aim to evaluate the efficacy of several treatments i.e. biocontrol agents, plant/microbial extracts, and bio-fungicides applied at a single time during the growing season against the most predominant pathogen in the PNW (Amiri and Ali, 2016). Trials will be conducted on Gala apple at Sunrise experimental orchard in Wenatchee, WA, for two successive seasons. Treatments will be applied with a backpack sprayer at appropriate timing and rates indicated on the label in a randomized complete block design (RCB) with four replicate trees for each treatment. Fruit will be picked (25 fruit/replicate tree for a total of 100 fruit/treatment) at commercial maturity and stored in separate crates at 34°F and 90% HR in a RA. Disease incidence and identification of pathogens will be carried out after 2, 4, and 6 months of storage or extended beyond as needed. Activity 1.2 and 1.3: Efficacy on detached fruit and Develop effective spray programs based on optimal timing and number of applications of combined treatments: To collect data on baseline efficacy of new materials they will be tested on detached fruit inoculated with major pathogens. Based on preliminary data and the efficacy from activity 1, the best treatments at bloom and preharvest will be combined for up to 5 applications from bloom to harvest. Extensive (up to 5 sprays/season) and conservative (1-2 sprays/season) spray programs will be designed and tested for two successive seasons as described in Activity 1.
Objective 2. Evaluate enhanced management tactics in three commercial orchards located in different productions regions of central Washington. Trials will be conducted in Years 2 & 3 at three commercial orchards in collaboration with our three cooperators: The first orchard is located in Tonasket (Godwin) north WA, the second (Stemilt) in central WA, and the third orchard (BZBlackrock) is located in south WA. The rationale is to test proposed management program on a larger commercial level and in different environmental conditions to ensure final recommendation would fit the needs of all stakeholders. At each site, a one-acre organic block of Gala or Honeycrisp (high value cultivars that suffer high disease incidence) will be divided by 2 subblocks. One sub-block will be sprayed following the grower spray calendar (one seven day preharvest spray) and the second sub-block will be sprayed using our proposed program of 3 to 4 sprays throughout the season i.e. at petal fall, fruitlet, green fruit and 7 days preharvest. Each sub-block will be divided into 4 sub-block replicates with equal number of trees. At commercial maturity fruit from each sub-block will be harvested separately by the cooperators in collaboration with PI-Amiri and his team. Fruit will be stored in a controlled atmosphere using the same conditions of commercial warehouses. After 6 months of storage, fruit will be packed in each commercial packinghouse and decayed fruit will be collected to determine incidence and decay type.
Objective 3. Evaluate the benefits of using dynamic control atmosphere (DCA), GRAS products and biocontrol agents to control rots in storage. (Year 1-2). While many benefits of DCA systems on the fruit quality and reduction of physiological disorders have been evidenced, the impact on disease reduction in such storage conditions is still unknown. The ability of fungi to survive in hypoxia varies but their metabolism is tremendously diminished. The DCA systems (O2 <1 to 0.3%) will only be relevant to pome fruit packers if a significant reduction in decay rate compared to static controlled atmosphere (1.5 to 3% oxygen) is shown. In Year 1 and 2, we will focus on 4 key postharvest pathogens, i.e., Botrytis cinerea, Neofabraea perennans, Penicillium expansum and Mucor piriformis. For the two first pathogens, Fuji apples will be inoculated with spore suspensions at 500,000 spores/ml on the trees 15 days prior to harvest to mimic pre-harvest conditions. For P. expansum and M. piriformis, fruit picked at commercial maturity, will be surface-disinfected in sodium hypochlorite, rinsed with sterile water, and inoculated with spore suspensions of each pathogen at 500,000 spores/ml. Fruit inoculated with each pathogen will be stored accordingly. Four replicates of 25 fruit each (total of 100 fruit/treatment) previously randomized using an RCB design will be used. Decay incidence and severity will be determined after 2, 4 and 6 months of storage. Additionally, 40 non-inoculated fruit (4 replicates of 10 fruit each), picked at commercial maturity, will be stored in the same atmospheres for the same storage periods and will be used to assess fruit quality parameters (firmness, solid content, sugar content, acidity). Fruit will be stored at Stemilt RCA rooms (Cooperator) for regular (RA) and controlled (CA) atmosphere treatments and in Safepod containers for the DCA treatment.
Research Outcomes
Objective 1. Evaluate the adequacy and efficacy of current and novel preharvest management organic strategies (Year 1-2)
Activity 1.1. Efficacy of existing and potential new products in the orchard: A Year 1 trial was initiated at a WSU experimental orchard in September 2022. Fruit are still in cold storage to mimic commercial storage period awaiting decay evaluation. Full results are expected in July 2023.
Activity 1.2: Efficacy on detached fruit. 14 organic materials were screened on detached Fuji apples for their efficacy against Penicillium expansum, Botrytis cinerea, Neofabraea perennans and Phacidiopycnis washingtonensis, four major postharvest pathogens of pome fruit. Results showed variability in their efficacy against the different pathogens. These results, together with those from Activity 1.1 will be used to select the best materials to be tested in Activity 1.3 in Year 2.
Activity 1.3. Develop effective spray programs based on optimal timing and number of applications of combined treatments: Planned for the 2023-24 season.
Objective 2. Evaluate enhanced management tactics in three commercial orchards located in different productions regions of central Washington. Planned in Years 2 and 3 based on results from Obj. 1.
Objective 3. Evaluate the benefits of using dynamic control atmosphere (DCA), GRAS products and biocontrol agents to control rots in storage. (Year 1-2). Fuji apples harvested in October 2022 at commercial maturity were inoculated with spore suspensions of Penicillium expansum, Botrytis cinerea, Neofabraea perennans or Phacidiopycnis washingtonensis, the four major postharvest pathogens of pome fruit. Fruit (100/pathogen) were incubated at 35°F in regular atmosphere (RA), static controlled atmosphere (CA), or dynamic controlled atmosphere (DCA). Fruit are still in storage awaiting inspection in July 2023.
Education and Outreach
Participation Summary:
Education and outreach activities are planned in Years 1 & 2 of this project.
Education and outreach activities are planned in Years 1 & 2 of this project.