Columbia Star blackberry variety

Columbia Star is a thornless, trailing blackberry cultivar from the U.S. Department of Agriculture - Agricultural Research Service (USDA-ARS) breeding program in Corvallis.
Columbia Star is the first thornless blackberry to be released with the Lincoln Logan source of thornlessness other than the original Lincoln Logan and Waimate that have Logan-type fruit and Marahau that has Boysen-type fruit. A main goal of the breeding program has been to develop a thornless blackberry with high yields and with fruit quality similar to Marion blackberry. Fresh fruit of Columbia Star are rated as having better firmness than either of the current industry standards. Although not yet evaluated in commerce, Columbia Star fruit have sufficient firmness for local fresh market sales, but it is not certain whether firmness would be sufficient for wholesale fresh shipping.
Fruit color was rated similarly to Black Diamond fruit and more black than those of Marion. Columbia Star and Marion are rated similarly for fruit texture and flavor as fresh fruit and both are considered better than Black Diamond. For flavor, Columbia Star has the highest rating, comparable to Marion and better than Black Diamond. Black Diamond has become the industry favorite for its yield, machine harvestability, and generally good fruit quality but many are of the opinion that its flavor could be better.
Average fruit weight is about 7 g. Average yield is about 7 kg per plant. Columbia Star ripens in the early midseason (at the beginning of July) for trailing blackberries and over 1 month earlier than Chester Thornless semi-erect blackberry. Within the trailing cultivars, Columbia Star harvest started as early as Black Diamond, a few days ahead of Marion, but reached the midpoint of harvest 5 days ahead of Black Diamond and 3 days ahead of Marion (from the beginning of July to the end of July). Columbia Star cultivar is vigorous, comparable to Marion, and the floricanes and primocanes are more vigorous than Black Diamond.
Columbia Star nuclear stock has tested negative for Tomato ringspot virus, Tobacco ringspot virus, Apple mosaic virus, Prunus necrotic ringspot virus, Cherry leaf roll virus, Raspberry ringspot virus, Arabis mosaic virus, Tomato black ring virus, Strawberry necrotic shock virus, Raspberry bushy dwarf virus, and Tobacco streak virus by enzymelinked immunosorbent assay and has tested negative for Raspberry leaf mottle virus, Raspberry latent virus, Rubus yellow net virus, Blackberry yellow vein associated virus, Blackberry virus Y, and Blackberry chlorotic ringspot virus in reverse transcription–polymerase chain reaction assays.
Winter hardiness is about minus 17 C.

Table 1. Yield and average berry weight at Oregon State University’s North Willamette Research and Extension Center (planted in 2009)

Cultivar	Berry weight, g	Yield, kg/plant
		2011	2012	2013
Columbia Star	7.6	7.8	6.17	8.52
Black Diamond	6.0	7.32	2.18	3.03
Marion	5.5	6.71	4.95	5.12

Table 2. Subjectively evaluated fruit quality traits for Black Diamond, Columbia Star and Marion blackberries (planted in 2009, scale from 1 to 9, where 9 is the best expression)

Cultivar	Columbia Star	Black Diamond	Marion
Firmness	7.6	6.7	4.1
Color	8.3	8.0	7.4
Shape	8.5	8.3	5.3
Texture	8.3	6.8	8.1
Flavor	8.1	6.4	8.4

Table 3. Soluble solids, pH and titratable acidity of fruit for Columbia Star, Black Diamond, Marion and Chester Thornless varieties (2011 - 2013 years)

Cultivar	Soluble solids, %	Titratable acidity, %	pH
Columbia Star	12.74	1.54	3.19
Black Diamond	10.28	1.22	3.38
Chester Thornless	11.69	1.05	3.28
Marion	12.57	1.56	3.21

Table 4. Harvest season (avg. from 2011 - 2013)

Cultivar	Ripening
	First (5%)	Peak (50%)	Last (95%)
Columbia Star	July 3	July 12	July 24
Black Diamond	July 3	July 17	July 26
Chester Thornless	August 5	August 28	Sept. 25
Marion	July 8	July 15	July 24