In 2006, organic blueberry production was a small but growing niche in Oregon — only about 2% of the state’s 4,400 acres were certified organic. Growers faced high input costs, uncertain yield potential, and a lack of research-based guidance. Organic fertilizers cost up to 10 times more than conventional options, and weed control was limited to expensive, less effective methods. Producers across Oregon and Washington approached Oregon State University Extension Service for solutions to determine whether organic systems could be both sustainable and economically viable.
In response, the Oregon State University Extension Service and the Oregon Agricultural Experiment Station launched the first long-term certified organic blueberry research trial of its kind in the world. The late Bernadine Strik, Extension berry crops specialist and professor in the Department of Horticulture, led the project beginning in 2006 with the establishment of a 1-acre certified organic planting at the North Willamette Research and Extension Center near Portland.
This work is widely considered the defining global research on ideal organic production systems for soil-grown blueberries.
Strik, who passed away in 2023, was a renowned researcher, educator and mentor. Her vision and leadership laid the foundation for modern organic blueberry production systems across the Pacific Northwest and beyond.
Initial seed funding came from the Oregon Blueberry Commission, with additional competitive support from the Washington Blueberry Commission and federal agencies. From 2007–2016, the trial tested variables including planting method (raised beds versus flat ground), mulch type (weed mat, sawdust, or compost plus sawdust), fertilizer source (fish solubles versus feather meal), and nitrogen rate. Two cultivars, 'Duke' and 'Liberty,' were studied.
From 2017–2020, the study focused on addressing issues caused by excessive potassium found in many organic fertilizers and compost. Researchers transitioned to potassium-free, nitrogen-only soybean-based fertilizer and modified mulch strategies to improve long-term plant health and yield.
The research delivered transformative results:
- Raised beds improved cumulative yield by 22% compared to flat ground, and are now standard for all new plantings.
- Weed mat mulch outperformed other options, increasing yields by up to 11% and reducing weed management costs by 75%. Adoption rose from 10% of new plantings in 2006 to more than 90% by 2020. Many conventional growers also adopted weed mat and reduced herbicide use, saving more than $100 per acre.
- Applying the lowest studied rate of fish solubles maintained high yields and saved growers approximately $900 per acre.
- Feather meal proved to be an effective and economical alternative to fish fertilizer, improving calcium uptake and reducing costs by up to 50%.
- Eliminating high-potassium compost and fertilizers increased yield in mature 'Duke' plants by as much as 50% over four years.
- Organic systems achieved yields and net returns comparable to conventional systems, supported by a 2011 cost-of-production study revised in 2020.
This work is widely considered the defining global research on ideal organic production systems for soil-grown blueberries. Results were shared through field days, Extension publications, eOrganic articles, webinars, and invited presentations in Canada, The Netherlands, Australia, Portugal, Chile and the United States.
The project was supported by five competitive federal grants and trained five graduate students, a postdoctoral research associate, a faculty research assistant, and numerous undergraduate students.
To date, the research has resulted in 10 refereed journal articles, eight peer-reviewed papers, two eOrganic articles, two webinars, and one OSU Extension publication. A 2019 article published in HortScience received the American Society for Horticultural Science’s Best Fruit Paper award in 2020. A 2012 publication was named Best Extension Paper by the same organization.
Thanks in large part to this research, organic acreage expanded dramatically. By 2020, Oregon’s organic blueberry acreage had grown to 20% of 15,000 total acres, with Washington adding 20,000 acres. Together, the region produced 60% of the United States’ organic blueberry crop in 2019.
Strik’s legacy continues to shape sustainable berry production. Her contributions established the Pacific Northwest as a global leader in organic blueberries and secured her reputation as one of the world’s foremost experts in organic berry crop systems.
