Cold Hardiness and Options for the Freeze Protection of Southern Highbush Blueberry

Southern highbush blueberries (SHB; Vaccinium corymbosum interspecific hybrid) are a low chill species of blueberry that are commercially grown in sub-tropical climates. Due to the nature of SHB, the flowering and fruit set occur in mid-winter to early spring and are susceptible to freeze damage. The most effective use of freeze protection is based on climatic conditions. Identification of advective or radiative freeze, intensity of the freeze event, and the equipment deployed are the key elements for deciding if the crop can be protected and justifying the expense to operate the system. Of the various methods used in frost protection, applying overhead irrigation water is the most promising. During a freeze event, an application of 6.3 mm ha−1 (0.10 in A−1) of water per hour is required to protect blueberries from −2.8 °C (27 °F) temperature with winds from 0 to 16 km h−1 (0 to 10 mph). This is 25.4 kL h−1 ha−1 (2715 gal h−1 A−1) of water. Overhead irrigation freeze protection is dependent on large volumes of water. This paper will review methods of freeze/frost protection, importance of weather patterns, and critical temperatures based on phenology of flowering to fruit set.

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Efficacy of Metalaxyl, Fosetyl-Aluminum, and Straw Mulch for Control of Strawberry Leather Rot Caused by Phytophthora cactorum

Plant Disease ◽

10.1094/pdis.1998.82.3.329 ◽

1998 ◽

Vol 82 (3) ◽

pp. 329-332 ◽

Cited By ~ 8

Author(s):

M. A. Ellis ◽

W. F. Wilcox ◽

L. V. Madden

Keyword(s):

Fruit Set ◽

Early Growth ◽

Early Spring ◽

Disease Development ◽

Phytophthora Cactorum ◽

Fungicide Treatment ◽

Straw Mulch ◽

Foliar Sprays ◽

Overhead Irrigation ◽

Significant Difference

Chemical and cultural controls for strawberry leather rot, caused by Phytophthora cactorum, were compared in replicated plots on a commercial farm near Wooster, Ohio. Straw mulch, applied uniformly for winter protection, was removed in early spring from between the rows of all check and fungicide treatment plots. Supplemental straw mulch was applied to other plots to achieve a level of approximately 9 t/ha. Overhead irrigation, which caused the soil to puddle, was provided on alternate days during rain-free periods to promote disease development (58, 66, and 73% incidence in check plots for 1993, 1994, and 1995, respectively). Foliar sprays of fosetyl-Al, applied weekly from bloom through preharvest at rates (a.i.) of 2.24 and 4.48 kg/ha, provided 88 to 96% control, with no significant difference between fungicide rates. Metalaxyl (1.17 kg/ha), applied either once or twice as a soil drench from early growth through fruit set, provided 82 to 94% control. Straw mulch alone provided 95 to 99% control. Thus, straw mulch between the rows was equally or more effective than fungicides for controlling leather rot.

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Effects of CPPU Applications on Southern Highbush Blueberries

HortScience ◽

10.21273/hortsci.42.7.1612 ◽

2007 ◽

Vol 42 (7) ◽

pp. 1612-1615 ◽

Cited By ~ 8

Author(s):

Jeffrey G. Williamson ◽

D. Scott NeSmith

Keyword(s):

Growth Regulator ◽

Field Experiments ◽

Fruit Set ◽

Vaccinium Corymbosum ◽

Highbush Blueberry ◽

Berry Size ◽

Spray Volume ◽

Highbush Blueberries ◽

Southern Highbush ◽

Spray Timing

Greenhouse and field experiments were conducted to determine the effects of the growth regulator N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) on fruit set, berry size, and yield of southern highbush blueberry (Vaccinium corymbosum hybrids). The experiments were conducted over a period of several years in Georgia and Florida. CPPU sprays were capable of increasing fruit set and berry weight of southern highbush blueberry, although the responses to CPPU treatment were variable and appeared to be influenced by factors such as rate, spray timing, and cultivar. In Florida, high natural fruit set may have prevented increased fruit set from CPPU. A slight delay in berry maturity was noted in several experiments. Spray burn occurred on several occasions and may be related to factors such as cultivar, rate, spray volume, and use of surfactant.

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Performance of Southern Highbush Blueberry Cultivars Under High Tunnels in Florida

HortTechnology ◽

10.21273/horttech.22.5.700 ◽

2012 ◽

Vol 22 (5) ◽

pp. 700-704 ◽

Cited By ~ 3

Author(s):

Bielinski M. Santos ◽

Teresa P. Salame-Donoso

Keyword(s):

Production Systems ◽

Effective Means ◽

Vaccinium Corymbosum ◽

Fruit Weight ◽

Highbush Blueberry ◽

Air Temperatures ◽

High Tunnels ◽

Southern Highbush ◽

Freeze Protection ◽

Open Fields

A study was conducted over two southern highbush blueberry (Vaccinium corymbosum × Vaccinium darrowi) seasons in a grower field in Florida. The objective was to compare the early fruit weight of southern highbush blueberry cultivars in high tunnels and in open fields. Four treatments were tested using combinations of two southern highbush blueberry cultivars (Snow Chaser and Springhigh) and two production systems (open fields and 18-ft-high tunnels). The results indicated that there was a significant effect of the production systems on the number of days with air temperatures at or near freezing (≤34 °F), and maximum and minimum air temperatures. The minimum air temperature in open-field plots reached ≈19 and 21 °F (61 freezing or near-freezing events) in the 2009–10 and 2010–11 seasons, respectively, whereas the minimum air temperatures inside the high tunnels were ≈32 and 33 °F, respectively, during the same seasons (only 3 days at ≤34 °F). This indicated that using high tunnels was an effective means to avoid freezing air temperatures in blueberries. In the first season, the cumulative early fruit weight was the highest in plots planted with ‘Snow Chaser’ inside the high tunnels (≈10 tons/acre), while the combined production of the two cultivars in the open fields did not reach 1 ton/acre until the end of the early harvests. The following year, there were no differences in the cumulative early fruit weight of both cultivars when planted in the open fields (2.2 tons/acre) and the cumulative fruit yields of ‘Springhigh’ and ‘Snow Chaser’ growing inside the high tunnels was twice and four times higher, respectively, than the early fruit production obtained in the open fields. These data showed the profound effect of high tunnels on flower protection and fruit set. High tunnels reduced water use for freeze protection. The total volume used in the open fields during the freezing or near-freezing days was ≈2.5 acre-inch/acre per 8 hours of freeze protection, whereas only 1/10 of that volume was applied inside the structures.

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Impact of Cross- and Self-pollination on Fruit Set, Fruit Size, Seed Number, and Harvest Timing Among 13 Southern Highbush Blueberry Cultivars

HortTechnology ◽

10.21273/horttech.26.2.213 ◽

2016 ◽

Vol 26 (2) ◽

pp. 213-219 ◽

Cited By ~ 4

Author(s):

Sarah K. Taber ◽

James W. Olmstead

Keyword(s):

Fruit Set ◽

Fruit Size ◽

Vaccinium Corymbosum ◽

Fruit Weight ◽

High Yield ◽

Highbush Blueberry ◽

Seed Number ◽

Cross Pollination ◽

Self Pollination ◽

Southern Highbush

Cross-pollination has been associated with improved fruit set, weight, and shortened time to ripening in southern highbush blueberry [SHB (Vaccinium corymbosum interspecific hybrids)]. Because of this, growers commonly plant two or more cultivars in small blocks to facilitate cross-pollination. However, many SHB cultivars may vary in the degree of improvement in each parameter after cross-pollination. Understanding the impacts of cross-pollination on a particular cultivar is crucial to forming planting recommendations, particularly as growers begin to transition to fields designed for machine harvest where large solid blocks would increase the harvest efficiency. The objective of this study was to examine the effects of cross- and self-pollination among 13 commonly planted or newly released SHB cultivars. Cross-pollination typically improved fruit set, fruit weight, and seed number while decreasing the average days to harvest. Cross-pollinated fruit always weighed more than self-pollinated fruit from the same cultivar, which was highly correlated to seed number per fruit. Although there was variation for each trait, interplanting with another unrelated cultivar sharing a similar bloom time remains the best recommendation to ensure early, high yield among these SHB cultivars.

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Effects of CPPU on Fruit Size, Set, and Yield of Southern Highbush Blueberry in Florida

HortScience ◽

10.21273/hortsci.39.4.793a ◽

2004 ◽

Vol 39 (4) ◽

pp. 793A-793

Author(s):

Jeffrey G. Williamson* ◽

E. Paul Miller

Keyword(s):

Fruit Ripening ◽

Fruit Set ◽

Fruit Size ◽

Vaccinium Corymbosum ◽

Limiting Factors ◽

Highbush Blueberry ◽

Fresh Weight ◽

Full Bloom ◽

Berry Size ◽

Southern Highbush

Poor fruit set and sub-optimum berry size are potential yield- and profit-limiting factors for southern highbush (Vaccinium corymbosum) blueberry production in Florida. The cytokinin N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) has increased fruit size and fruit set of a number of fruit crops including rabbiteye blueberry. The purpose of this study was to determine the effects of CPPU applied at different rates and phenological stages of bloom and/or fruit development on fruit size, set, and yield of southern highbush blueberry. `Millennia' and `Star' southern highbush blueberry plants located on a commercial blueberry farm in Alachua County, Fla., were treated with 5 or 10 ppm CPPU at various stages of development ranging from full bloom to 20 days after full bloom. In contrast to findings with rabbiteye blueberry, fruit set in this study of southern highbush blueberry was not affected by any of the CPPU treatments when compared to the controls. Nor was total fruit yield affected by CPPU treatments. The most noticeable potential benefit found in this study was an increase in mean fruit fresh weight from CPPU treatments. However, cultivars responded differently to CPPU with respect to mean fruit fresh weight. For `Millennia', only one CPPU treatment increased mean fruit weight compared to controls. However, for `Star', all but one CPPU treatment increased mean fruit fresh weight. Several CPPU treatments resulted in delayed fruit ripening for `Star' but not for `Millennia'. For `Star', the treatments that most consistently delayed fruit ripening tended to have greater fruit fresh weights.

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Evaluation of Southern Highbush Blueberry Cultivars for Production in Southwestern Arkansas

HortTechnology ◽

10.21273/horttech.12.2.271 ◽

2002 ◽

Vol 12 (2) ◽

pp. 271-274 ◽

Cited By ~ 3

Author(s):

P. Manjula Carter ◽

John R. Clark ◽

R. Keith Striegler

Keyword(s):

Fruit Quality ◽

Cold Hardiness ◽

Vaccinium Corymbosum ◽

Highbush Blueberry ◽

Chilling Requirement ◽

Production Potential ◽

Vaccinium Ashei ◽

Early Ripening ◽

Quality And Reliability ◽

Southern Highbush

Southern highbush blueberry, a hybrid of northern highbush (Vaccinium corymbosum) and southern-adapted Vaccinium species, has the potential to meet the need for an early-ripening blueberry in the southern U.S. southern highbush cultivars can ripen up to one month earlier than the earliest rabbiteye (Vaccinium ashei) cultivars currently grown in the southern U.S. However, chilling requirement and cold-hardiness are cultivar-dependent for southern highbush and cultivar testing has been necessary to determine the cultivars best adapted to specific hardiness zones. In a 4-year study at Hope, Ark. (hardiness zone 7b), several southern highbush cultivars were evaluated for productivity, fruit quality and reliability of cropping. Yields were based on 1089 plants/acre (2690 plants/ha) for southern highbush cultivars and 605 plants/acre (1494 plants/ha) for rabbiteye cultivars. `Ozarkblue' and `Legacy' showed the most adaptability at this location, yielding on average 11,013 lb/acre (12,309 kg·ha-1) and 10,328 lb/acre (11,543 kg·ha-1) respectively, compared to 4882 lb/acre (5456 kg·ha-1) for `Premier' (rabbiteye) over 4 years. `Ozarkblue' and `Legacy' also rated well for plant vigor and fruit quality. We would recommend `Ozarkblue' and `Legacy' for commercial planting in southwest Arkansas and believe these cultivars have production potential for other areas of the southern U.S. that have similar hardiness zones and soil type to southwest Arkansas.

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FRUITING IN SOUTHERN HIGHBUSH BLUEBERRIES: POLLEN SOURCE AND HONEY BEE POLLINATION EFFICIENCY

HortScience ◽

10.21273/hortsci.27.6.613f ◽

1992 ◽

Vol 27 (6) ◽

pp. 613f-614

Author(s):

Robert G. Danka ◽

Gregory A. Lang

Keyword(s):

Honey Bees ◽

Fruit Set ◽

Floral Morphology ◽

Vaccinium Corymbosum ◽

Fruit Weight ◽

Bee Pollination ◽

Bee Foraging ◽

Highbush Blueberries ◽

Southern Highbush ◽

Net Cages

`Gulfcoast' southern highbush blueberry (Vaccinium corymbosum × V. darrowi) plants were placed in 3 × 6 × 2.5 m net cages with one colony of honey bees per cage and one of three pollinizer treatments: “self (other `Gulfcoast' plants), “cross/highbush” (other southern highbush cultivars), or “cross/rabbiteye” (various rabbiteye blueberry cultivars). In addition to unlimited pollination, bee foraging was controlled on individual flowers by placing small bags over corollas after 0, 1, 5, or 10 visits. Fruit set, fruit weight, fruit development period, and seed number data were taken, as well as data to relate floral morphology to duration of bee foraging. All measures of fruiting increased significantly with increased bee visitation; the threshold for significant gains in production occurred between 1 and 5 visits. Ten visits generally provided a good approximation of unlimited pollination. Set, weight, and earliness of ripening was as good, or better, for fruit derived from rabbiteye pollen compared to fruit from self- or cross/highbush-pollination.

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Foliar Applications of Calcium and Boron Do Not Increase Fruit Set or Yield in Northern Highbush Blueberry (Vaccinium corymbosum)

HortScience ◽

10.21273/hortsci12207-17 ◽

2017 ◽

Vol 52 (9) ◽

pp. 1259-1264 ◽

Cited By ~ 4

Author(s):

Matthew Arrington ◽

Lisa Wasko DeVetter

Keyword(s):

Pacific Northwest ◽

Fruit Set ◽

Vaccinium Corymbosum ◽

Climatic Conditions ◽

Tissue Type ◽

Highbush Blueberry ◽

Foliar Sprays ◽

Growing Seasons ◽

The Pacific ◽

Northern Highbush Blueberry

Fruit set in northern highbush blueberry (Vaccinium corymbosum L.) can be low under certain climatic conditions, contributing to reduced yields in northwestern Washington. The mechanisms influencing fruit set are complex, but reduced fruit set may be associated with inadequate nutrient availability during critical stages of flowering, ovule fertilization, and initial fruit development. Calcium (Ca) and boron (B) are of particular interest for reproductive developmental processes and are frequently applied annually by growers in the Pacific Northwest region because of the perception that these nutrients enhance fruit set and corresponding yields. Evaluation of commonly applied products containing these nutrients and their effects on fruit set and yield are of specific importance to justify the application of these nutrients. To address this, commercially available fertilizers containing Ca and B were applied to ‘Draper’ and ‘Bluecrop’ blueberry as foliar sprays, either alone or in combination, during the 2015 and 2016 growing seasons in northwestern Washington. Treatments included calcium chloride (750 and 1500 ppm Ca), calcium sulfate (150 ppm Ca), and tetra borate (125 and 250 ppm B) foliar sprays, repeated six times per season every 7–10 days from early pink bud through petal fall. No significant increases were observed for fruit set, estimated yield, and fruit quality (firmness and berry weight) across the treatments. Increased concentrations of B were observed in leaf tissues in 2015 and 2016, and to a lesser extent fruit tissues. Calcium remained unchanged regardless of treatment and tissue type. Under the conditions of this study, foliar applications of Ca and B did not lead to increased fruit set or yield. This research suggests that other approaches should be explored to increase fruit set and corresponding yields of highbush blueberry grown in northwest Washington.

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Honey-bee-mediated Cross- versus Self-pollination of `Sharpblue' Blueberry Increases Fruit Size and Hastens Ripening

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.116.5.770 ◽

1991 ◽

Vol 116 (5) ◽

pp. 770-773 ◽

Cited By ~ 19

Author(s):

Gregory A. Lang ◽

Robert G. Danka

Keyword(s):

Apis Mellifera ◽

Honey Bee ◽

Honey Bees ◽

Fruit Set ◽

Fruit Size ◽

Vaccinium Corymbosum ◽

Cross Pollination ◽

Early Ripening ◽

Southern Highbush ◽

Early Market

To study self- and cross-pollination effects on fruit development in southern highbush (mainly Vaccinium corymbosum L.) blueberries, `Sharpblue' plants were caged with honey bees (Apis mellifera L.) and other `Sharpblue' or `Gulfcoast' plants at anthesis. Ratios of pollinizer: fruiting flowers ranged from 2.1 to 4.5. Cross-pollination increased fruit size by ≈14% and seed count by 27% but did not influence fruit set. Overall, seed count decreased by 58% during the 30 days of harvest, but this did not directly affect fruit size. Seed count appeared to influence earliness of ripening as much as it influenced fruit size. Cross-pollination increased the harvest percentage of early-ripening fruits by ≈140% and of premium market fruits (those ≥ 0.75 g) by 13% and decreased the percentage of small fruits by 66%. Consequently, a 43% increase in premium early market crop value (nearly $5000/ha) resulted from optimizing `Sharpblue' cross-pollination.

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Early and Mid-fall Defoliation Reduces Flower Bud Number and Yield of Southern Highbush Blueberry

HortTechnology ◽

10.21273/horttech.12.2.214 ◽

2002 ◽

Vol 12 (2) ◽

pp. 214-216 ◽

Cited By ~ 12

Author(s):

J.G. Williamson ◽

E.P. Miller

Keyword(s):

Fruit Set ◽

Vaccinium Corymbosum ◽

Fruit Yield ◽

Negative Effects ◽

Flower Bud ◽

Experiment Control ◽

Early Fall ◽

Southern Highbush ◽

High Yields ◽

Bud Initiation

Three experiments were conducted in north-central Florida to determine the effects of fall defoliation on flower bud initiation and yield of southern highbush (SHB) blueberry (Vaccinium corymbosum hybrid). In 1998, randomly selected upright shoots of mature, field-grown `Misty' and `Sharpblue' plants were hand-defoliated at monthly intervals beginning 4 Sept. and ending 7 Dec. In 1999, a similar study was conducted using different plants of the same cultivars. Representative shoots were defoliated at monthly intervals beginning 14 Sept. and ending 15 Dec. Additional shoots were also partially defoliated by removing the distal two-thirds of each leaf at monthly intervals from 15 Oct. through 15 Dec. In a third experiment, 2-year-old container-grown `Star' SHB plants were completely defoliated at monthly intervals beginning 13 Sept. and ending 15 Dec. In each experiment, control shoots, or plants ('Star'), were not defoliated. Although there were differences among cultivars and years, all cultivars tested demonstrated negative effects on reproductive growth and development from September and October defoliations. For `Sharpblue', reduced fruit yield from early fall defoliation appeared to be due to fewer fruit set per flower bud. However, for `Misty', reduced fruit yield from early fall defoliation was the result of large reductions in flower bud numbers as well as fewer fruit set per flower bud. September and October defoliations of `Star' reduced yields or delayed fruit ripening. Collectively, these experiments demonstrate the importance of maintaining healthy foliage through October in the lower southeastern United States for adequate flower bud initiation and high yields of SHB blueberry the following spring.

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