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Primocane-fruiting blackberry (Rubus subgenus Rubus Watson) selections have recently been developed by the University of Arkansas, but proper cane-management practices for the new germplasm have not yet been determined. It was observed in previous trials that primocane-fruiting selections flowered and fruited in late July and early August in Arkansas, which is often the hottest part of the summer and earlier than desired. Therefore, this study was conducted to determine the effects of primocane tipping on cane and fruit characteristics and to determine the effect of floricane presence on primocane performance. In Fayetteville, one-year-old plants of selections APF-8 and APF-12 were used to apply the four primocane-tipping treatments in combination with the two cane management treatments (presence or absence of floricanes). In Clarksville, the same genotypes were used to apply the two cane management treatments (presence or absence of floricanes). The tipping treatments had a significant effect on primocane yield and peak harvest as well as other parameters. The cane management treatments had a significant effect on total yield, but no other effects.

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Little research has been done to determine the chilling requirement for southern blackberry cultivars. However, field observations from areas where low amounts of chilling occur indicate that `Navaho' requires more hours of chilling than does `Arapaho'. The objective of the study was to determine a method for measuring chilling requirement using whole plants of two blackberry cultivars, Arapaho and Navaho. One-year-old bare-root plants of `Arapaho' and `Navaho' were field-dug and placed in a cold chamber at 3 °C. Ten single-plant replications of each cultivar were removed at 100-hour intervals up to 1000 hours. The plants were then potted and placed in a greenhouse (daily minimum temperature 15 °C) in a completely randomized design. Budbreak was recorded on a weekly basis. Data for budbreak was analyzed as a two-factor factorial (two cultivars and 10 chilling treatments) by SAS and means separated by lsd (P = 0.05). Data indicated that the chilling requirement for `Arapaho' is between 400 and 500 hours. This is evident as a 6-fold increase, which was the largest increase between two chilling treatments, occurred between 400 and 500 hours. For `Navaho', the largest increase (also 6-fold) occurred between 800 and 900 hours, which indicated a chilling requirement for `Navaho' of 800 to 900 hours. These data support previous observations and indicate the method used was successful in determining chilling requirement for blackberries.

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`Jupiter' is the fifth table grape cultivar released from the Univ. of Arkansas grape breeding program. `Jupiter' originated from a cross of Ark. 1258 × Ark. 1672 made in 1981. The original seedling vine was selected in 1984, and `Jupiter' was tested as Ark. 1985. `Jupiter' was tested at two locations in Arkansas (Fayetteville and Clarksville) and at West Lafayette, Ind. Fruit of `Jupiter' are reddish-blue, and berry weight averaged 5.5 g over 12 years of evaluation at Clarksville. Fruit are seedless, have a non-slipskin texture, ripen early mid-season, and averaged 19.8% soluble solids. Flavor is a mild muscat, a noteworthy character of this new cultivar. Clusters averaged 257 g over 12 years and are well-filled. Yields of `Jupiter' have been very good, exceeding 29 t/ha at Clarksville. Hardiness of `Jupiter' was greater than `Einset Seedless', `Himrod', or `Vanessa Seedless', but less than `Mars' or `Reliance' at West Lafayette. `Jupiter' is recommended for trial where other other eastern U.S. table grape cultivars are adapted.

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Applications of N to blackberry plantings are a common practice in Arkansas, but fertilizer recommendations are largely based on those of other states. The need for information on fertility of a new blackberry from the Arkansas breeding program motivated this study. A three-year-old `Arapaho' blackberry planting at the University of Arkansas Fruit Substation was used for this study. Treatments which began in 1994 and continued through 1996 were: 1) control—no N applied, 2) 56 Kg N/ha applied in a single application in early spring, 3) 112 Kg N/ha applied in a single early spring application, and 4) 112 Kg/ha applied in a split application with one-half applied in the early spring and one-half applied immediately after harvest. Fruit was harvested from the plots in June and total yield and average berry weight determined. Foliar samples were collected in August and elemental analysis conducted. Primocanes in each plot were counted at the end of the growing season. Over the three years, there was no significant treatment effect on yield, berry weight, or primocane number. A trend toward higher primocane number where N was applied was seen, however. Foliar levels of N, P, K, Ca, S, and Mn were affected by either N rate or time of application. The foliar N levels were influenced by N rate and the split application gave the highest concentration. Calcium was higher when no N was applied, Mn was greater at higher N rates while the control had the lowest foliar N level in each year.

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Small fruit production in the southern United States has been impacted greatly by fruit breeders this century. This workshop, co-sponsored by the American Pomological Society, includes presentations from individuals who have contributed collectively over 150 years to small fruit and grape breeding. James N. Moore has conducted breeding at the University of Arkansas, developing 30 cultivars. His presentation on brambles outlines achievements and future opportunities for improvement. Arlen Draper has been involved with the development of 61 small fruit cultivars while working with the USDA-ARS with an emphasis on blueberry. His presentation focuses on blueberry breeding and provides insights into the future of new blueberry cultivar developments. Gene Galletta has conducted small fruit breeding at North Carolina State University and USDA-ARS and has been involved with the development of 50 cultivars. His presentation reflects on the history of strawberry breeding in the South and the challenges that lie ahead. Ron Lane has served as a fruit breeder and horticulturist at the University of Georgia Experiment Station at Griffin and his work has emphasized the development of muscadine grape cultivars. The past and future of muscadine and bunch grape breeding is discussed in his paper. Articles from all authors in this workshop will be published in Fruit Varieties Journal in 1997.

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An investigation was conducted in 1994 and 1995 to evaluate the effect of N rate and timing of application on postharvest performance of `Arapaho' thornless blackberry fruit. Treatments were 0 kg N/ha, 56 kg N/ha, 112 kg N/ha single application, and 112 kg N/ha split application. The N source was ammonium nitrate. Fruit samples were hand-harvested and stored for 0–8 days. In general, `Arapaho' fruit quality was not affected by N applications. Increasing N rates increased soluble solids content but had no effect on pH, titratable acidity, sugar: acid ratio, total solids, firmness, and weight loss. Nitrogen applications increased fruit N content.

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Chilling requirement, (the number of hours below 7 °C necessary to break dormancy) has been shown to vary with genotype in blackberry (Rubus subgenus Rubus). Previous work has demonstrated that the chilling requirement of field-grown plants could be accurately determined from stem cuttings of lateral shoots taken at 100-hour intervals of chilling up to 1000 hours, by placing them in a mist chamber maintained at 26 °C with a daylength of 16 hours, and observing budbreak over a period of 5 weeks. This technique has previously demonstrated clear differences in the chilling requirements of thorny and thornless floricane-fruiting cultivars. In the current study, a comparison of floricane-fruiting and primocane-fruiting blackberries using the stem-cutting technique illustrated a lower chilling requirement associated with the primocane-fruiting trait. The use of the stem-cutting technique can be a simple and effective tool for assessing blackberry adaptation to different hardiness zones.

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The postharvest life of blackberries is shortened by decay, leakage, and softness. Shelf life is shortened after periods of rainfall, and often fruit that appear firm in the field soften rapidly in storage. Blackberry selections of interest for advanced selections from plants without fungicide application are routinely screened for shelf life at Lane by storing fruit at 5 °C for seven days. Blackberry varieties are increasingly being used for farmer's markets, national, and international markets. A rapid test to gauge shelf life of blackberry varieties new to growers would be useful in determining the best type of marketing. Ripe blackberries were harvested from Clarksville, Ark., and transported in 260 g plastic clamshells on ice (about 5 °C) to Lane, Okla. Berries were weighed upon arrival and placed at 5 or at 20 °C for 7 and 2 days, respectively. Overall ratings were considerably worse at 20 °C compared to 5 °C, often with decay on all fruit in clamshells held at 20 °C. Separate subsamples of berries, placed individually in egg cartons and held over water at 20 °C (a 99% relative humidity) yielded Rhizopus, Collectotricum, and Botrytis cinerea growth after 24 hours. Because 2 days at 20 °C proved to cause decay in blackberries too quickly, fruit will be held for 1 day at 20 °C in the next season.

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