Pre and Postharvest Disease Management of Pome Fruit to Support an Expanding Organic Production in the Pacific Northwest

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Commodities

• Fruits: apples, pears

Practices

• Pest Management: biological control, biorational pesticides, botanical pesticides, integrated pest management, physical control
• Production Systems: organic agriculture

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.