Blackberries are a very important specialty crop in the United States, especially in Oregon, where they are particularly suited to the climate (Strik and Finn, 2012). In Oregon, 23.9 million kilograms of conventional blackberries were produced on 2954 ha in 2011 (National Agricultural Statistical Service, 2013). In 2008, organic blackberries were harvested on a reported 348 farms in the United States for a crop value of $4.6 million (Geisler, 2012). Given the 12% growth of sales from 2009 to 2010 (Organic Trade Association, 2011) for organic fruits and vegetables, the outlook for organic blackberry production continues to be positive.
Organic production requires the use of various cultural and biological methods for pest management and the use of natural fertilizer sources (animal, plant, or mined origin) for nutrient management [U.S. Department of Agriculture (USDA), 2011]. In organic production, fertigation, the application of fertilizer through a drip irrigation system, has become more common (Fernandez-Salvador, 2014; Harkins et al., 2013; Schwankl and McGourty, 1992). System design and costs (Gaskell and Smith, 2007) need to be considered when adopting irrigation/fertigation systems. Blackberry fields can be successfully established using drip irrigation (Harkins et al., 2013), but fertigation with organic fertilizer sources may lead to plugging of the drip emitters over time (Fernandez-Salvador et al., 2015a). In the present study, organically approved liquid fertilizers that could be fertigated were selected.
Weed management during planting establishment is important for maximizing plant growth and yield (Harkins et al., 2013). The use of woven polyethylene groundcovers (“weed mat”) has been shown to be an effective weed management strategy in plantings of trailing and semierect blackberry plants that do not produce primocanes from root buds (Fernandez-Salvador et al., 2015b; Harkins et al., 2013; Makus, 2011).
Growers who focus on fresh market production systems are interested in growing blackberry cultivars that extend the fruiting season, have a high yield, and produce high-quality fruit. Cultivars must have good postharvest fruit quality and an acceptable shelf life for shipping and for storage, which can range from 14 to 21 d (Fan-Chiang and Wrolstad, 2010; Joo et al., 2011; Perkins-Veazie et al., 1996, 1999, 2000; Perkins-Veazie and Clark, 2002). Unlike in conventional production (Finn et al., 1997, 2005a, 2005b, 2005c, 2011; Strik, 1992; Strik and Finn, 2012), there is relatively little information available on cultivar adaptation to organic production systems (Fernandez-Salvador et al., 2015b; Harkins et al., 2013).
The objectives of our study were to evaluate four fresh market blackberry cultivars (‘Obsidian’, ‘Black Diamond’, ‘Onyx’, ‘Metolius’) and two advanced selections (ORUS 1939-4, ORUS 2635-1) in an organic production system during the establishment years. Genotypes were compared for plant growth and yield and postharvest fruit quality and marketable days at 5 °C. ‘Obsidian’ is a trailing cultivar with vigorous plant growth, very high yield, and large fruit. As a primarily fresh market blackberry, it has excellent flavor and ripens early in the northwestern United States (Finn et al., 2005a; Finn and Strik, 2014). Under conventional management, yield and berry weight for ‘Obsidian’ ranged from 19 to 28 t·ha−1 and 5.5 to 6.8 g, respectively (Finn et al., 2005a). ‘Black Diamond’ is the second most important cultivar grown for processing in Oregon, where its characteristic high yield and thornless canes make it well suited to machine harvesting (Finn et al., 2005a; Finn and Strik, 2014). Yield has been as high as 21 t·ha−1 in conventional production (Finn et al., 2005a) and 13 to 17 t·ha−1 in organic production systems (Fernandez-Salvador et al., 2015b; Harkins et al., 2013). ‘Black Diamond’ may also be hand-harvested for fresh market, because fruit are large, firm, uniformly shaped, and have good flavor (Finn et al., 2005a). ‘Onyx’ is a relatively new cultivar producing vigorous canes and a moderate yield of uniform, firm, sweet, and excellent-flavored fruit suited for local and wholesale fresh markets (Finn et al., 2011). Yield of ‘Onyx’ averaged 14 t·ha−1 in conventional management systems (Finn et al., 2011). ‘Metolius’ is characterized by vigorous plant growth, a good yield, and medium-sized, firm fruit with excellent flavor (Finn et al., 2005b). In conventional production trials, the trailing, thorny ORUS 1939-4 had high yields with medium to large, firm, sweet fruit with excellent flavor. ORUS 2635-1 is a high-yielding selection that produces high-quality, large fruit on a fairly erect, thorny plant (Strik et al., unpublished data).
Bell, N.C., Strik, B.C. & Martin, L.W. 1995 Effect of primocane suppression date on ‘Marion’ trailing blackberry. I. Yield components J. Amer. Soc. Hort. Sci. 120 21 24
Cortell, J.M. & Strik, B.C. 1997 Effect of floricane number in ‘Marion’ trailing blackberry. II. Yield components and dry mass partitioning J. Amer. Soc. Hort. Sci. 122 611 615
Dahnke, W.C. 1990 Testing soils for available nitrogen, p. 120–140. In: Westerman, R.L. (ed.). Soil testing and plant analysis. Soil Sci. Soc. Amer. Book Series 3. SSSA, Madison, WI
Fernandez-Salvador, J.A. 2014 Nutrient management of blackberry cultivars grown in organic production systems. Master’s thesis, Oregon State Univ., Corvallis, OR. 15 July 2014. <http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/49147/Fernandez-SalvadorJavierA2014.pdf?sequence=3>
Fernandez-Salvador, J.A., Strik, B.C. & Bryla, D. 2015a Liquid corn and fish fertilizers are good options for fertigation in blackberry cultivars grown in an organic production system HortScience 50:225–233
Fernandez-Salvador, J.A., Strik, B.C. & Bryla, D. 2015b Response of blackberry cultivars to fertilizer source during establishment in an organic fresh market production system HortTechnology (in press)
Finn, C.E. & Strik, B.C. 2014 Blackberry cultivars for Oregon. EC 1617-E. Oregon State University, Corvallis, OR
Finn, C.E., Yorgey, B.M., Strik, B.C., Hall, H.K., Martin, R.R. & Qian, M. 2005a‘Black Diamond’ thornless trailing blackberry HortScience 40 2175 2178
Gavlak, R.G., Horneck, D.A. & Miller, R.O. 1994 Soil and plant tissue reference methods for the western region. Univ. Alaska Western Reg. Publ. 125
Geisler, M. 2012 Blackberries. Agricultural Marketing Resource Center. Iowa State Univ., Ames. 5 Mar. 2014. <http://www.agmrc.org/commodities__products/fruits/blackberries/>
Harkins, R.H., Strik, B.C. & Bryla, D.R. 2013 Weed management practices for organic production of trailing blackberry: I. Plant growth and early fruit production HortScience 48 1139 1144
Harkins, R.H., Strik, B.C. & Bryla, D.R. 2014 Weed management practices for organic production of trailing blackberry: II. Accumulation and loss of biomass and nutrients HortScience 49 35 43
Hart, J., Strik, B. & Rempel, H. 2006 Caneberries. Nutrient management guide. Ore. State Univ. Ext. Serv., EM8903-E, Corvallis, OR
Joo, M., Lewandowski, N., Auras, R., Harte, J. & Almenar, E. 2011 Comparative shelf life study of blackberry fruit in bio-based and petroleum-based containers under retail storage conditions Food Chem. 126 1734 1740
McLean, E.O. 1982 Soil pH and lime requirement, p. 199–223. In: Page, A.L. (ed.). Methods of soil analysis, Part 2. Agronomy Monograph 9. 2nd Ed. ASA and SSSA, Madison, WI
Mohadjer, P., Strik, B.C., Zebarth, B.J. & Righetti, T.L. 2001 Nitrogen uptake, partitioning and remobilization in ‘Kotata’ blackberry in alternate-year production J. Hort. Sci. Biotechnol. 76 700 708
National Agricultural Statistical Service 2013 Oregon berry production. U.S. Dept. Agr., Natl. Agr. Stat. Serv., Washington, DC
Nelson, D.W. & Sommers, L.E. 1996 Total carbon, organic carbon and organic matter, p. 961–1010. In: Bartels, J.M. (ed.). Methods of soil analysis: Part 3. Chemical methods. 3rd Ed. ASA and SSSA Book Series 5, Madison, WI
Organic Trade Association 2011 Industry statistics and projected growth. Organic Trade Association, Washington, DC. 5 Mar. 2014. <http://www.ota.com/organic/mt/business.html>
Perkins-Veazie, P. & Clark, J.R. 2002 Quality of erect-type blackberry fruit after short intervals of controlled atmosphere storage Postharvest Biol. Technol. 25 235 239
Perkins-Veazie, P., Clark, J.R., Huber, D.J. & Baldwin, E.A. 2000 Ripening physiology in ‘Navaho’ thornless blackberries: Color, respiration, ethylene production, softening, and compositional changes J. Amer. Soc. Hort. Sci. 125 357 363
Perkins-Veazie, P., Collins, J.K. & Clark, J.R. 1996 Cultivar and maturity affect postharvest quality of fruit from erect blackberries HortScience 31 258 261
Perkins-Veazie, P., Collins, J.K. & Clark, J.R. 1999 Shelf-life and quality of ‘Navaho’ and ‘Shawnee’ blackberry fruit stored under retail storage conditions J. Food Qual. 22 535 544
Schwankl, L.J. & McGourty, G. 1992 Organic fertilizers can be injected through low volume irrigation systems Calif. Agr. September–October 21 23
Sullivan, D.M., Strik, B.C. & Bryla, D. 2015 Evaluation of alternative mulches for blueberry over five production seasons Acta Hort. (in press)
U.S. Department of Agriculture 2011 Organic Foods Production Act Provisions. Title 7 Part 205 Code of Federal Regulations. U.S. Dept. Agr. Marketing Serv., Natl. Organic Program, Washington, DC