Blackberry Schultz Fruiting

Arapaho Blackberry

Rubus spp

The earliest ripening thornless variety. Lots more to pick at once because it ripens its fruit in a 4 week period. Can be planted farther south. Arapaho needs only 400-500 chill hours (hours with temperatures below 45*F). PP# 8510. zone 6-8.degrees F) Plant Patent # 8510. The outstanding characteristics of Arapaho are its thornless, erect, self supporting canes, good fruit quality, earliness of ripening and its ability to establish a full fruiting row quickly. Zone 6-8.
Blackberry Arapaho Blooms
Arapaho Blooms

HortScience, Vol. 28(8), August 1993

'Arapaho' Erect, Thornless Blackberry

James N. Moore and John R. Clark
Department of Horticulture and Forestry, University of Arkansas, Fayetteville, AR 72701

A long-term goal of the Univ. of Arkansas, Fayetteville, blackberry breeding program has been to develop erect-caned, thornless blackberries (Rubus L. subgenus Eubatus) that do not require trellis support. The first such cultivar, 'Navaho', was released from this program in 1998 (Moore and Clark, 1989) and quickly became popular with home gardeners and commercial "pick-your-own" growers. 'Navaho', however, has two shortcomings: it ripens very late in the season when summer temperatures are high and it produces new canes only sparingly from roots, a characteristics that delays fruiting-row establishment. 'Arapaho' is early ripening, erect, thornless, and quickly establishes a full fruiting row. It is expected to complement 'Navaho' and expand the harvest period for high-quality thornless blackberries.

'Arapaho', tested as Ark. 1536, resulted from a cross of Ark. 631 x Ark. 883 made in 1982 (Fig. 1). Both parents of 'Arapaho' are thorny but are heterozygous for recessive genes for thornlessness. These genes were obtained from the British cultivar Merton Thornless via 'Thornfree' (Scott et al., 1957). The erect growth habit of 'Arapaho' was contributed by the erect, thorny cultivars Darrow, Hillquist, and Cherokee. All cultivars and selections listed in the 'Arapaho' pedigree are tetraploids. The original 'Arapaho' plant was selected from a seedling field in 1985. It has been tested at three locations in Arkansas and distributed for tests at several other state experiment stations.

'Arapaho' fruit yields have been less than those of 'Navaho' at Fayetteville and Clarksville, Ark., but higher than those of 'Navaho' at Hope, Ark. (Table 1). The yield difference between 'Arapaho' and 'Navaho' was greater at Fayettville and Clarksville in 1992 (a year of late spring freezes) than in 1991, perhaps indicating greater spring frost susceptibility of 'Arapaho'. Both thornless cultivars were less productive than the thorny cultivars Shawnee and Choctaw, except that 'Navaho' yielded as well as 'Choctaw' at Clarksville and was equal to 'Shawnee' and 'Choctaw' at Fayetteville. 'Arapaho' fruit size, measured as average berry weight, compared with that of 'Navaho' was larger at Hope, of similar size at Clarksville, and smaller at Fayetteville. 'Arapaho' fruit were as large as or larger than 'Choctaw' fruit but smaller than 'Shawnee' fruit at all locations.

'Arapaho' fruit are short-conic and bright glossy black (Fig. 2). Fruit are firm, as estimated manually , similar to 'Navaho' and firmer than 'Shawnee' or 'Choctaw' (Table 2). We rated flavor as equal to that of 'Navaho' and better than that of 'Shawnee' of 'Choctaw'. Soluble solids concentration, determined with a hand-held refractometer, was high but slightly lower than that of 'Navaho'. An important positive characteristic of 'Arapaho' is its small seed size. Seeds are significantly smaller, i.e., lighter than those of 'Navaho' and 'Shawnee' but slightly larger than those of 'Choctaw'. 'Arapaho' fruit storage performance was similar to that of 'Navaho' after 2 days of storage at 4C but was slightly lower after 4 and 7 days of storage (data not shown). Both thornless cultivars stored significantly better than 'Shawnee' or 'Choctaw' at all storage durations.

A notable feature of 'Arapaho' is its earliness of fruit ripening (Table 2). It ripens ~ 11 days earlier than 'Navaho' and 2 days before 'Shawnee' and is the earliest ripening thornless blackberry cultivar known to us at this time. The fruiting period of 'Arapaho' is concentrated into <4 weeks in contrast to the usual 5 to 6 week fruiting period of 'Navaho'.

'Arapaho' plants are moderately vigorous and very erect in growth habit (Table 2). Plants have good resistance to cold injury at temperatures as low as -24C (-11.2F). No disease problems have been noted following a fungicide program consisting only of one application of liquid lime-sulfur at budbreak. No orange rust [Gymnoconia nitens (Schwein.) F. Kern & H.W. Thurston] has been observed on 'Arapaho' when grown in areas of high inoculum. The reaction of plants to rosette [Cercosporella rubi (Wint.) Plakidas] has not been determined definitively, but no symptons have been observed on 'Arapaho' after 2 years of field tests in an area of high inoculum at Calhoun, La. (B. Buckley, personal communication). 'Arapaho' is more prolific in producing primocanes from roots than 'Navaho'. In field tests 90% of 'Arapaho' root cuttings produced plants compared to 75% for 'Navaho'.

The outstanding characteristics of 'Arapaho' are its thornless, erect, self-supporting canes, good fruit quality, earliness of ripening, and its ability to establish a full fruiting row quickly.

Figures & Tables are coming...

Plant Characteristics
Pest ResistanceExcellent
Disease ResistanceExcellent
Drought ToleranceVery Good
Heat ToleranceGood
Humidity ToleranceVery Good
Sun ToleranceVery Good
Wet Soil ToleranceFair
Shade ToleranceFair
No SprayExcellent
Salt ToleranceGood
Fresh for KidsGood
Deer ResistanceFair
Soil TypeAdaptable
Edible TypeBerry
Self FertileYes
This information is accurate to the best of our knowledge, comments/opinions are always welcome
Click Here for the Arapaho Blackberry Careguide

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