Organic Blackberry Production Systems

The goal of this project is to develop organic production systems for processed and fresh blackberry that maximize plant growth, yield, fruit quality, and food safety; facilitate weed and irrigation management; provide healthy and nutritious food; and provide the greatest economic benefit to growers.

The research will be conducted on campus at Oregon State University and North Carolina State University, at the North Willamette Research and Extension Center, OSU, and at grower collaborator sites in Oregon and in the Southeastern USA.

In the main planting at the NWREC, trailing blackberry cultivars are being evaluated in various organic production systems for the processed market. Treatments include: cultivar (Marion and Black Diamond); irrigation (post-harvest and no post-harvest irrigation); weed management (weed mat, hand-hoed, and non-weeded); and primocane training date (August and February). Data to be collected on treatment effects include: plant growth (vigor, dry weight and nutrient accumulation), plant nutrient status, yield (machine harvest), fruit weight, firmness, fruit quality before and after IQF (drip loss, soluble solids concentration or Brix, juice pH, total acidity, total phenolics, anthocyanins, vitamin C, ORAC and FRAP values, flavor as determined by a sensory panel, and reddening, (a problem in processed fruit), fruit shelf-life, plant and soil water status, soil nutrient content, root growth, weed pressure, disease incidence, and impact of production system and harvest method (hand or machine) on bacterial load of fruit.

In addition, the effect of fertilizing with either hydrolyzed fish or corn steep liquor at the same rate of nitrogen is being compared in Marion and Black Diamond.

The guard rows are being used to evaluate the response of fresh blackberry cultivars to an organic production system. Five trailing cultivars, Black Diamond, Onyx, Metolius, Boysen, and Obsidian, and two advanced selections (about to be released), ORUS 1939-4 and 2635-1, are being grown for fresh market. We will collect data on: plant growth (vigor, dry weight and nutrient accumulation), harvest index, plant nutrient status, yield (hand harvest), fruit weight, firmness, Brix, and fruit shelf-life.

These studies are too new to have many results to share. The planting will be harvested for the first time in 2012. In 2011, plants with weed mat required up to 30% more irrigation water to maintain the same water potential (plant water status) as those in hand-weeded and non-weeded plots, particularly in Marion, which often had lower leaf water potentials than Black Diamond. To date, there has been no significant effect of weed management practices on plant nutrient status, although Marion tended to have a lower leaf N concentration in non-weeded plots. Soil pH was higher in non-weeded plots than under weed mat in 2010 but not in 2011. Overall, findings to date suggest that weed management may directly affect soil and plant nutrient status. Next year, we will begin to ascertain the effects of weed management as well as post-harvest irrigation and primocane training date on plant growth, yield, and berry nutrients.

Bernadine C. Strik, Professor, Dept. Horticulture & Berry Crops Research Leader, NWREC
David Bryla, USDA-ARS, HCRU, Corvallis

Acknowledgements

We thank the following individuals for their significant contributions to this project: Emily Vollmer (Research Assistant, Dept. Hort.) and Gil Buller (Senior Research Assistant, NWREC); Renee Harkins and Javier Fernandez (M.S. Students, Dept. Hort), Luis Valenzuela (Post-doc, Dept. Hort. & USDA-ARS), Yanyun Zhao and Mark Daeschel (Dept. Food Sci.), Dan Sullivan (Dept. Crop & Soil Sci.), Chad Finn (USDA-ARS), Diane Kaufman (formerly NWREC); Vaughn Walton (Dept. Hort., OSU).

We also thank our advisory board members: Eric Pond (Riverbend Organic Farms, OR); Joe Bennett (Small Planet Foods, WA); Tom Avinelis (Homegrown Organic Farms, CA); Derek Peacock (Hurst's Berry Farms, OR); Josh Beam (SunnyRidge Farms, FL); Anthony Boutard (Ayers Creek Farm, OR); John Vollmer (Vollmer Farms, NC)

We greatly appreciate the financial, research grant support and in-kind contributions from: National Institute for Food & Agriculture (NIFA) – Organic Research & Extension Initiative (OREI); Oregon Organic Cropping grant; Northwest Center for Small Fruits Research; Eric Pond (Agricare Inc.); Riverbend Farms (Jefferson, Oregon); Sakuma Bros. Farms (Burlington, Washington), Oregon Tilth