Blackberry Production in Oregon
Dr. Bernadine Strik, Associate Professor, Horticulture, Extension Berry Crops Specialist, Oregon State University
This paper was originally presented at the 11th Annual Conference of the North American Bramble Growers Association, January 31 – February 4, 1996.
Oregon is the leading blackberry production region in the world with 6,180 acres producing 42.6 million pounds in 1995. There are three types of blackberries grown in Oregon: trailing (‘Marion’, ‘Boysen’, ‘Thornless Evergreen’); erect (‘Shawnee’, ‘Cherokee’, ‘Arapaho’); and semi-erect (‘Chester Thornless’, ‘Hull Thornless’). Most of the acreage (over 95%) is planted to the trailing types which are best suited to processing. About 98% of the blackberry crop was processed in 1995 with about 75% of the trailing acreage estimated as being machine harvested. The erect and semi-erect blackberries are predominantly marketed fresh with excess fruit being processed.
‘Marion’ (OSU/USDA, 1956) is the leading blackberry cultivar with 3,500 acres accounting for 56% of the total harvested blackberry acreage in 1995. This cultivar is highly prized by the processing industry for its unique, good flavor, small seed size (or “presence”), medium to large sized fruit (averaging 4.8g) and good texture for processing. Fruit are dull black in color. This cultivar is always sold with a cultivar designation. ‘Marion’, despite its relative sensitivity to cold injury and thorny canes, is still the cultivar of choice in new plantings. Grower price the last few years has ranged from 30 to 89› in the 1991-95 period; fluctuations are mainly due to supply/demand as affected by cold injury.
‘Thornless Evergreen’ (Rubus laciniatus) is the second most planted commercial trailing blackberry. A thornless clone (periclinal chimera) of this cultivar was selected from wild harvested stands. A genetically thornless cultivar, identical (tissue culture propagation) to ‘Thornless Evergreen’, called ‘Everthornless’ is now available commercially. However, new plantings of either of these cultivars are relatively few due to the poor grower price the last few years — averaging $0.39 per pound. However, this cultivar does offer the advantage of higher per acre yields than ‘Marion’, a greater tolerance to cold temperatures, and a harvest season in August when growers are done with most other berry crops. Fruit average about 3.5 grams in weight and are glossy black in color. All of the ‘Thornless Evergreen’ production in Oregon is processed and sold as a generic “blackberry” product.
‘Boysen’ (1935, California) is a hybrid containing some red raspberry genes through its parentage. Acreage of ‘Boysen’ and ‘Thornless Evergreen’ are very similar in Oregon at about 1,200 harvested acres in 1995. ‘Boysen’ is sold with cultivar identification due to its very unique flavor and appearance. Seeds are more apparent than those of ‘Marion’, but the flavor, color and texture make this cultivar very desirable for processing. Fruit average 8.5 grams and are maroon color.
‘Kotata’ (OSU/USDA, 1984) was released as a possible replacement for ‘Marion’. However, although the flavor of ‘Kotata’ is good and they are similar in appearance to those of ‘Marion’, this cultivar cannot be sold as a “Marion” and is often sold as a generic “blackberry”. ‘Kotata’ is more vigorous and has slightly greater cold tolerance and fruit firmness than ‘Marion’. However, canes are very thorny.
‘Waldo’ (OSU/USDA, 1989) was the first genetically thornless trailing blackberry cultivar released. Despite this major advantage in addition to a relatively small seed size and firm fruit, this cultivar is not widely planted. Plants lack sufficient vigor making management more difficult and fruit lack the “Marion” flavor.
‘Logan’ a raspberry blackberry hybrid discovered in California is losing its market niche with only 80 acres harvested in 1995. Most of this production is sold for wine or is marketed fresh.
Essentially all of the trailing blackberry crop is processed with the exception of some ‘Logan’, ‘Boysen’, ‘Kotata’, and ‘Waldo’ fruit. Most of our fresh blackberry market, albeit relatively small, relies on the blackberry types better suited to fresh shipping, the erect and semi-erects.
Our active cooperative blackberry breeding program led by the USDA/ARS geneticist, Chad Finn, focuses on developing a more cold hardy, thornless “Marion” type well suited to processing.
Trailing blackberries are long-lived perennial crops — about a 15 year lifespan. Plantings are usually established in the spring from tissue culture at a spacing of 4 to 6′ in the row (narrower for ‘Waldo’ and ‘Boysen’ and wider for ‘Thornless Evergreen’) with 10′ between rows for machine harvest.
Growers often harvest a “baby crop” the year after planting. Full production starts in year 3. Typical yields are 4-5 tons/acre for ‘Thornless Evergreen’, 2-4 for ‘Boysen’ and 3-4 tons/acre for ‘Marion’ in every year production (EY) and 5.5 for alternate year (AY) producing fields in the “on year”.
As much as 55% of the ‘Marion’ acreage in the past has been in alternate year production. However, I estimate that about 20% of ‘Marion’ fields are AY; this drop in percentage has been mainly due to the occurrence of significant cold events and crop loss in the last 6 years. In alternate year production, primocanes are produced one year, the “off year”, and allowed to fruit the following year, the “on year” (Sheets et al., 1975). Some growers suppress early primocanes in the “on year” to prevent interference with machine harvesting (Lipe and Martin, 1984). The AY system yields about 70% to 90% as much as the traditional every-year (EY) production system over a 2-year period (Bullock, 1963; Martin and Nelson, 1979). There are, however, economic advantages to producing blackberries in the A-Y system including reduced labor for pruning and training and reduced pesticide costs (especially due to a reduction in cane disease caused by Septocyta ruborum and Septoria rubi). Plants in AY production, following and “off year” have been observed to be more cold hardy than those in EY production (Bell et al., 1992).
Since 1950, severe winter conditions have reduced the ‘Marion’ crop by a minimum of 25% on six occasions. In December 1990, temperatures as low as 0 F in the Willamette Valley reduced the 1991 ‘Marion’ crop by 70%. Cultural practices have been shown to affect cold hardiness of ‘Marion’ (Bell et al, 1992; 1995b).
In general, the floricanes of plants in every year production are removed after harvest. Primocanes are then trained to the trellis in August (summer-trained) or February (winter-trained). Summer-trained plants produce about 46% greater yield than winter-trained plants through an increased percentage of bud break and greater fruit per lateral (Bell et al, 1995a). Winter-trained plants are generally more cold hardy as canes are not exposed on the trellis during cold periods. However, training just prior to a cold spell in February may increase risk of cold injury (Bell et al, 1992).
In general, primocanes are trained on a 2-wire trellis (top wire at 5 1/2′ and another 1 1/2′ below that) with half the canes from a plant woven around the two wires in one direction and the other half trained in the other direction. In AY production, the primocanes and floricanes are cut from the plant in October of the fruiting year. The following year, the “off year”, primocanes are trained as they grow. Growers with their fields in AY production have half in the “on year” and half in the “off year” in a given season.
Relatively few trailing blackberry growers suppress primocanes in AY or EY production, due mainly to the lack of a very effective chemical primocane suppressant. However, with recent research indicating that primocane suppressed plants produce about 20% greater yield the following season than unsuppressed plants (Bell et al, 1995a) and that late primocane suppression increases subsequent cold hardiness (Bell et al, 1995b) this may change.
Primocane suppression also facilitates machine harvest and about 75% of the trailing blackberry acreage is estimated to be machine harvested for processing.
Trailing blackberries are harvested by hand or machine about every 4 to 5 days. Fruit are usually harvested in the early morning as it releases more easily at this time. About 98% of the trailing blackberry crop is processed as IQF (individually quick frozen), bulk frozen pack, or puree.
The most important production problem and the one that limits the range of production of trailing blackberry is the relative lack of cold hardiness. In most years we see cold damage to ‘Marion’, ‘Boysen’, and ‘Logan’ buds at about 8 F; however, we can get injury at higher temperatures in late winter, particularly when the cold spell follows a warm period. In recent research with ‘Marion’ and ‘Kotata’ we’ve shown that as much as 75 to 100% primary bud loss can be compensated for by fruit production on secondary laterals (paper in progress).
Many trailing blackberry cultivars, especially ‘Marion’, are sensitive to the cane diseases cane spot (Septoria rubi) and purple blotch (Septocyta ruborum) that reduce yield and may increase sensitivity to cold injury. Downy mildew (Peronospora sparsa) has greatly reduced yield in some ‘Kotata’ and ‘Boysen’ fields by rendering fruit hard and unmarketable. The red berry mite (Acalitus essigi) overwinters in bud scales and feeds at the base of drupelets in spring and summer causing persistence of red color at harvest time; this pest is especially a problem in ‘Thornless Evergreen’. Botrytis fruit rot and u.v. sun damage may also be a problem in some years. Although root weevils, nematodes, and phytophthora root rot have been found in blackberry fields, these are usually not a problem unless the field has a large amount of pest pressure.
The trailing blackberry acreage has been stable with a slight increase the last few years. ‘Marion’ is by far the leading cultivar of choice in new plantings. However, inconsistency of yield, through mainly crop loss to cold injury in some years, is a major problem that adversely affects marketing. Although the industry could use a “Marion type” cultivar that is thornless and more cold tolerant, in the meantime we are studying potential alternative production systems that will likely increase consistency of yield. Presently we are studying the use of higher density plantings in combination with primocane suppression at various dates in EY and AY production systems.
In 1990 there were about 70 acres of erect blackberries in Oregon with 200 acres estimated to be planted by the year 2000 (Strik, 1992). The intended market for most of this acreage is fresh. All of the acreage is hand harvested.
The most commonly planted cultivars are ‘Cherokee’ (Univ. of Arkansas, 1974) and ‘Shawnee’ (Univ. of Arkansas, 1985). The genetically thornless ‘Arapaho’ (Univ. of Arkansas, 1992) is also being planted. However, we are seeing a problem with primocane tip die-back and premature branching in this cultivar. Growers in Oregon feel that ‘Cherokee’ has superior growth, yield, and fruit quality to ‘Shawnee’. Fruit weight averages about 8 grams.
Erect blackberries are established in hedgerows, usually using tissue cultured plants. The first crop is typically harvested in year 3. Yields average 3-4 tons/acre. Primocanes are topped by hand during the growing season at about 3′. The subsequent branches are not pruned by hand, but rather a hedgerow is maintained by machine pruning in winter. The old floricanes are not removed, but are left in the row to add support and eventually break off and decompose. There is usually no trellis used. Irrigation, as for all the blackberries grown in Oregon, is usually done with moveable overhead impact sprinklers.Harvest is done by hand in early morning. Fruit for fresh market are rapidly cooled, often by forced air and are packaged for shipping. Fruit that cannot be fresh marketed are processed and sold as a generic “blackberry” product. Most of the seeds must be removed as they are much larger than those of ‘Marion’, for example.
In 1990 there were about 45 acres of semi-erect blackberries in Oregon with 150 acres estimated to be planted by the year 2000 (Strik, 1992). The intended market for most of this acreage is fresh. All of the acreage is hand harvested.
The most widely planted cultivar is ‘Chester Thornless’ (USDA, 1985) which has very high yields (averaging over 12 tons/acre), and good flavored, firm fruit of medium size (5.5 grams). ‘Hull Thornless’ (USDA, 1981) is also planted, although fruit are not as firm.
Semi-erect blackberries, in Oregon, are typically grown on a 4-wire trellis with two cross-arms on posts in a “double ‘T’” arrangement. Plantings are established in spring from tissue culture. Plants are set about 6′ apart in rows 12′ apart. Primocanes are topped at about 6′ to encourage branching. However, these branches are not usually further pruned, but are trained on the double T trellis. We see tremendous yields with this production system, without an apparent loss in fruit size. Dead floricanes are removed after harvest.
Irrigation, as for all the blackberries grown in Oregon, is usually done with moveable overhead impact sprinklers. However, overcanopy microsprinklers are often used to cool fruit during hot summer days with low humidity; this helps prevent u.v. or sunburn damage, the major production problems.
Harvest is done by hand in early morning. Fruit for fresh market are rapidly cooled, often by forced air and are packaged for shipping. Fruit that cannot be fresh marketed are processed and sold as a generic “blackberry” product. Again, most of the seeds must be removed as they are much larger than those of ‘Marion’, for example.
Bell, N., E. Nelson, B. Strik, and L. Martin. 1992. Assessment of winter injury to berry crops in Oregon, 1991. Oregon State University Agricultural Experiment Station, Special Report 902, July, 1992, 23 pp.
Bell, N., B. Strik, and L. Martin. 1995a. Effect of primocane suppression date on ‘Marion’ trailing blackberry. I. Yield components. J. Amer. Soc. Hort. Sci. 120:21-24.
Bell, N., B. Strik, and L. Martin. 1995b. Effect of primocane suppression date on ‘Marion’ trailing blackberry. II. Cold hardiness. J. Amer. Soc. Hort. Sci. 120:25-27.
Bullock, R.M. 1963. Spacing and time of training blackberries. Oregon Hort. Soc. Proc. 55:59-60.
Lipe, J.A. and L.W. Martin. 1984. Culture and management of blackberries in the United States. HortScience 19:190-193.
Martin, L.W. and E.H. Nelson. 1979. Establishment and management of ‘Boysenberries’ in Western Oregon. Oregon State University Agr. Expt. Sta. Circ. 677.
Sheets, W.A., T.L. Nelson, and A.G. Nelson. 1975. Alternate-year production of ‘Thornless Evergreen’ blackberries: technical and economic feasibility. Ore. State Univ. Agr. Expt. Sta. Bul. 620.
Strik, B.C. 1992. Blackberry cultivars and production trends in the Pacific Northwest. Fruit Var. J. 46:202-206.