Organic Blueberry Production Research Project
by Bernadine Strik, Emily Vollmer, Gil Buller, David Bryla and Dan Sullivan
Department of Horticulture, NWREC, USDA-ARS and Crop & Soil Science Department, Oregon State University

This project, established as a certified organic planting at the North Willamette Research and Extension Center, was initiated in response to industry requests and was designed with input from an advisory group that included growers using both conventional and organic production systems, as well as leaders in the nursery and fresh and processed fruit handling industries.

The long-term goal of this project is to develop organic production systems for highbush blueberry that maximize plant growth, yield and fruit quality, facilitate weed, water and nutrient management and provide economic benefit to growers.

Organic Blueberry Production research plots at the OSU North Willamette Research & Extension Center. June 4, 2009.
The study was established at the Oregon State University NWREC in October 2006 and was certified organic in May 2008. Treatments consist of two cultivars (“Duke” and “Liberty”), two production methods (raised bed or flat ground), three weed management practices (sawdust mulch + hand weeding; compost [yard debris] + sawdust mulch + organic herbicides as needed; and landscape fabric [weed mat]) and two types and rates of organic fertilizer (feather meal and liquid fish fertilizer at 25 or 50 lb. N/a in 2007-2009 and 45 and 90 lb. N/a in 2010).

Our key findings to date are briefly described here. We highlight this planting at our annual Blueberry Field Day at the NWREC. More detailed progress reports are available upon request.

Cumulative yield from years two - four (2008-10) was 48 percent greater on raised beds than flat ground, corresponding to improved plant growth. Although the soil at this research site is considered to be well-drained, there was still an advantage to growing on raised beds. Yields for the raised bed plantings have, in general, been similar to what is expected for conventional fields, averaging about four tons/acre in 2010 (year four).

On average, plants fertilized with the high rate of feather meal or the low rate of fish emulsion had the greatest yield, whereas fertilizing with the highest rate of fish emulsion tended to reduce yield in both cultivars to date. Leaf tissue %N was higher than recommended levels in plants fertilized with the high rate of fish.Plants mulched with yard debris compost topped with sawdust (compost+sawdust) and weed mat produced greater yield than those mulched with sawdust in 2009 and 2010.

Duke and Liberty had lower fruit firmness when fertilized with the low rate of feather meal than with fish emulsion or the high rate of feather meal. Duke fruit were firmer and had higher percent soluble solids (Brix) when fertilized with a high rate of fish emulsion. Our goal is to determine why fertilizer is affecting fruit firmness.

Weed pressure has been consistently low with weed mat and high with compost+sawdust. In 2010, for example, sawdust+compost mulched plots required 83 hr/acre for hand-weeding and 20 hr/acre for contact herbicide application (total of 103 hr/acre + $60/acre product) compared to 88 hr/acre to hand-weed in sawdust and 18 hr/acre in weed mat mulched plots.

Percent soil moisture was maintained in a suitable range for good plant growth through careful management of irrigation. In 2007-09 weed mat plots received approximately double the irrigation water as sawdust mulched plots, but in 2010 there was less difference in irrigation applied among treatments. Raised beds required more irrigation water than flat ground plantings in 2007-09, but not in 2010. We think these differences are mainly due to soil temperature as affected by mulch type or depth and plant canopy size (shading). Soil temperature was warmer under weed mat than under the organic mulches, particularly in raised bed plantings.

Work on shoot growth rate, fruit bud set, tissue and soil nutrient status, soil microbial content, weed management, production economics, root growth and development of a compost suitable for blueberry were also conducted in 2009-2010 and work is on-going so please stay tuned!

While this planting is still relatively young, growth and yield for most treatments have been similar to what has been observed in conventional systems. The best treatments so far have been growing plants on raised beds with a low rate of fish emulsion or a high rate of feather meal on either weed mat or compost+sawdust mulch. Economic returns to date have been comparable to conventional systems, depending on the organic production method used.

We thank our advisory board members and the organizations that have provided funding for this project: The Oregon Blueberry Commission, the Northwest Center for Small Fruits Research, the Washington Blueberry Commission, the NIFA-OREI grant and industry contributors.


Message from the Chairman

Spotted Wing Drosophila Update

Market Outlook:
A Look Back …
and Ahead

Bumbles and Blueberries

Organic Blueberry Production Research Project

Critical Program Needs Industry Support

Small Growers to Receive GAP Certification Aid

Oregon Fresh Season Promotion On a Roll for 2011

Bee Fees Jump a Bit

Smooth Move Increases Insulin Sensitivity

New Trap Hits
the Spots
(Spotted Wing Drosophila)

OSU Researcher Driving Blueberries up a Tree

USHBC Unveils New “Little Blue Dynamos” Positioning and Campaign for Highbush Blueberries

Watching World Acreage and
Production Grow

Specialty Crop Grant Supports Oregon Berry Festival;
Free Berry Vendor Space Available


Oregon Blueberry Commission • P.O. Box 3366 • Salem, Oregon 97302
Paid for by the Oregon Blueberry Commission, an agency of the State of Oregon.