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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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Bearing `Misty' and `Star' southern highbush blueberries were grown on pine bark beds and fertilized at three rates using granular and liquid fertilizers with a 3–1–2 (1N–0.83K–0.88P) ratio. Granular fertilizer was applied 8 times per year at 4-week intervals beginning in April and continuing through October. Liquid fertilizer was applied with low volume irrigation 16 times per year at 2-week intervals during the same period. During the growing season, irrigation was applied at 2- to 3-day intervals in the absence of rain. A 2 cultivar × 2 fertilizer type × 3 fertilizer rate factorial arrangement of treatments was replicated 8 times in a randomized complete-block design. All fruits were harvested from single-plant plots at 3- to 4-day intervals. Canopy volume was not affected by fertilizer type, but fruit yield was slightly greater for granular than for liquid fertilizer treatments. In 2003, fruit yield of 2.5-year-old `Misty' and `Star' plants increased with increasing fertilizer rates up to the highest rate tested (50 g N/plant/year). Similarly, in 2004, fruit yields increased with increasing fertilizer rates up to the highest rate (81 g N/plant/year). Root distribution was limited to the 12-cm-deep layer of pine bark with very few roots penetrating into the underlying soil. The positive growth responses of blueberry plants to high fertilizer rates in pine bark beds suggests that soluble fertilizer was leached through the pine bark layer into the soil below the root zone. More frequent, lighter applications of soluble fertilizers, use of slow-release or controlled-release fertilizers, and careful irrigation management may improve fertilizer use efficiency of blueberry plantings on pine bark beds.

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Abstract

A block of 2-year-old ‘Starkrimson Delicious’ apple (Malus domestica Borkh.) trees growing in Somerville, Victoria, Australia were treated with 0 to 500 ppm BA when terminal growth was 2 cm. BA application initially increased the rate of lateral shoot growth. However, the growth rate rapidly slowed and extension growth on the lateral shoots stopped earlier than on untreated trees. There was a linear increase in the number of lateral shoots and a linear reduction in the length of these lateral shoots as the concentration of BA was increased. BA forced more lateral shoots to grow at the tip of the branch than at the base, although shoots at the base of the limbs grew longer. A reduced concentration of BA was required to stimulate spurs to grow out into lateral shoots on the vigorous, more upright central leader. Lateral shoots were longer on the central leader than on the scaffold branches, indicating tree and/or branch vigor may be a major factor in producing good scaffold limb development following BA application. Notching forced more spurs to form lateral shoots on the central leader, and these shoots grew longer than those on the scaffold limbs. Notching increased the number of buds developing into lateral shoots following BA application. May and Baker 25-105 increased the number of lateral shoots on a tree. This result occurred both on untreated trees and on those that previously received 400 ppm BA. Reducing the number of lateral shoots by pinching apices of shoots soon after BA application was the most effective method to increase the length of BA-induced lateral shoots. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine (BA) (2-chloroethyl)phosphonic acid (ethephon), butanedioic acid mono(2,2-diemthylhydrazide) (daminozide), propyl 3-t-butylphenoxyacetate (May and Baker 25-105).

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The American Chestnut Foundation (ACF) has conducted a breeding program aimed at developing blight-resistant chestnut trees exhibiting the phenotype of American Chestnut (Castanea dentata). We developed a protocol for in vitro micropropagation and multiplication of candidate blight-resistant plants from the ACF breeding program. The protocol included forcing dormant shoots to budbreak, culture establishment, shoot multiplication, inducing a functional root system on the microcuttings produced by this system and establishment of autotrophic plants. Because Castanea spp. is recalcitrant to rooting, a unique bilayer method of rooting was developed. The unique bilayer consisted of a clear basal medium of 50% DKW and 50% WPM (Long and Preece), with a continuous level of 0.01 mg IBA/L and 0.2 mg BA/L. The clear basal medium was over-laid with an opaque layer. Rooting response occurred for 27 of the 31 genotypes at various frequencies. Rooted plantlets were planted in 50% peat: 50% perlite in order to become autotrophic and acclimated. Acclimated trees were planted in 10″ × 2″ Deepots® and placed in the greenhouse. These trees exhibited a very vigorous functional root system. Acclimated trees were hardened off, placed in cold storage (≈4-5 °C) for 5 months. All trees placed in cold storage broke dormancy for spring growth and ≈100 trees were sent to ACF for planting into field trials.

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The demand for hot sauce products continues to expand in the U.S. In the case of jalapeno pepper sauce, there are many cultivars available for sauce production but those best suited for processing have not been adequately determined. Six cultivars (four replications) of jalapeno peppers (`Coyame', `Grande', `Jalapeno-M', `Mitla', `Tula' and `Veracruz') were evaluated for mash fermentation. The attributes studied during mash aging were color spectra, capsaicin content and fermentable sugars. Fructose and glucose were the predominant sugars in jalapeno peppers and these sugars were utilized gradually with time indicating slow fermentation by microorganisms in the 15% salt mash. Capsaicin and dihydrocapsaicin were the predominant capsaicinoids in the jalapeno peppers with `Tula' containing the greatest concentration and `Veracruz' the least. All mashes displayed an apparent and unexpected rise in measurable capsaicinoids up to 6 months with a decline at 12 months. Color changes in the pepper mash were rapid initially but slowed after the first month of fermentation. Percent reflectance in fresh ground peppers was strongest in the range of 550–560 nm but, after salting, reflectance shifted to 580–590 nm and remained throughout the fermentation. Based on the characteristics tested, any of these cultivars would make a suitable mash for sauce. The heat content of the final product could be controlled by cultivar selection or through blending.

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The American Chestnut Foundation (ACF) has conducted a breeding program aimed at developing blight-resistant chestnut trees exhibiting the phenotype of American Chestnut [Castanea dentata (Marsh) Borkh]. Because such plants are difficult to propagate, we developed a protocol for in vitro multiplication of candidate blight-resistant plants resulting from the ACF breeding programs. Dormant shoots were taken from 5- to 8-year-old trees and forced, producing softwood growth for use as a source of explants for shoot multiplication. Best shoot proliferation took place on WPM containing 0.2 mg BA/L. Explant material for the rooting experiments was taken from 6- to 12-month-old proliferating cultures. The basal rooting medium consisted of WPM containing 0.01 mg IBA/L and was overlaid with a thin opaque layer. Rooting was enhanced overall with this bilayer approach. A “D/W” medium (DKW and WPM) was also used as a rooting medium containing 0.01 mg IBA/L and 0.2 mg BA/L, which further enhanced leaf quality and rooting for some genotypes. After several transfers on the bilayer system, explant growth appeared to become less juvenile in stem and leaf development and more analogous to mature later-season growth. The rooting responses and the time for rooting to be induced were highly variable among the different genotypes.

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Many plants have mechanisms of physical or chemical resistance that protect them from herbivores in their environment. Vertebrates such as meadow voles (Microtus pennsylvanicus) cause significant damage to ornamental plantings and home gardens. Our goal was to identify flowering bulbs that could be used to design more herbivore-resistant home landscapes. Single-choice feeding trials with captive prairie voles (Microtus ochrogaster) were used to assess the relative resistance of 30 bulb varieties to deter rodents from consuming fresh plant material and freeze-dried, powdered bulb mixed with a preferred food (applesauce). Each fresh bulb and dried-bulb/applesauce mix was offered twice to 12 to 15 pairs of adult prairie voles. Bulb varieties that resulted in the lowest mean consumption were assumed to be the most resistant to feeding activity. With fresh bulbs, only tulips (Tulipa spp.) exhibited no resistance to prairie vole feeding. Dried-bulb/applesauce mixes containing hyacinth (Hyacinth spp.), crocus (Crocus spp.), corn leaf iris (Iris bucharica), dutch and dwarf iris (Iris reticulata), onion (Allium spp.), and squill (Scilla siberica) were also readily consumed, and thus, these bulbs could be damaged at sites with high rodent activity. Daffodil (Narcissus spp.), painted arum (Arum italicum), camass (Camassia leichtlinii), glory-of-the-snow (Chinodoxa forbesii), autumn crocus (Colchicum spp.), crown imperial (Fritillaria imperialis), persian fritillaria (Fritillaria persica), snowdrop (Galanthus nivalis), and grape hyacinth (Muscari armeniacum) bulbs were resistant to prairie vole feeding in both forms (fresh bulbs and dried-bulb/applesauce mixes). Consequently, all of the specialty flower bulbs tested, except tulip, exhibited some resistance to prairie vole feeding in their fresh form, and could be suitable for designing herbivore-resistant landscapes.

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Postbloom sprays of BA thinned `McIntosh', `Delicious', `Golden Delicious', `Mutsu, `Empire', and `Abas' apples. BA at 75 to 100 mg·liter-1 was equal to NAA at 6 to 7.5 mg·liter-1 or carbaryl at 600 to 800 mg·liter-1. BA increased fruit size, flesh firmness, and soluble solids concentration (SSC) on all cultivars evaluated. Since BA is applied during the time when cell division is occurring, it is concluded that the increased fruit size and flesh firmness were due to Increased cell numbers. Increased SSC was not due solely to increased leaf: fruit ratio. Thinning with BA was additive with other chemical thinners and no interactions were found on fruit abscission. In most eases, BA increased return bloom. Chemical names used: N-(phenylmethyl)1H-purine-6-amine [benzyladenine (BA)]; 1-naphthaleneacetic acid (NAA); 1-naphthalenyl methylcarbamate (carbaryl); butanedioic acid mono(2,2dimethylhydrazide (daminozide); (2-chloroethyl)phosphonic acid (ethephon).

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Experiments were conducted in north Florida and south Georgia to determine the effects of H2CN2 sprays on vegetative and reproductive growth of blueberry. In Florida, mature, field-grown `Misty' southern highbush (Vaccinium corymbosum L. hybrid) blueberry plants were sprayed to drip with 0, 10.2, or 20.4 g·L-1 of H2CN2 [hereafter referred to as 0%, 1.0%, and 2.0% (v/v) H2CN2] on 20 Dec. 1996 and 7 Jan. 1997. During the following winter, mature `Misty' southern highbush and `Climax' rabbiteye (V. ashei Reade) plants were sprayed to drip with 0, 7.6, or 15.3 g·L-1 of H2CN2 [hereafter referred to as 0%, 0.75%, and 1.5% (v/v) H2CN2] on 17 Dec. 1997 and 6 Jan. 1998. For all experiments, plants were dormant and leafless, with slightly swollen flower buds, at the time of spray applications. Generally, H2CN2 sprays increased the extent and earliness of vegetative budbreak and canopy establishment and advanced flowering slightly. The number of vegetative budbreaks usually increased linearly with increasing spray concentrations. In Florida, H2CN2 [0.75% to 1.0% (v/v)] sprays increased mean fruit fresh weight and yield, and shortened the fruit development period (FDP) compared to controls. However, H2CN2 sprays ranging in concentration from 1.5% to 2.0% (v/v) resulted in significant flower bud injury and reduced total fruit yield compared to controls. In south Georgia, 27 of 37 field trials conducted between 1991 and 1998 on several rabbiteye and southern highbush cultivars indicated that leaf development was significantly enhanced by H2CN2. H2CN2 shows potential for increasing early fruit maturity, fruit size, and yield of southern highbush and rabbiteye blueberry cultivars with poor leaf development characteristics in low-chill production regions. Chemical name used: hydrogen cyanamide (H2CN2).

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Nonweighing drainage lysimeters were used to measure seasonal water use of mature ‘Emerald’ southern highbush blueberry (SHB; Vaccinium corymbosum interspecific hybrid) plants grown in pine bark beds and in pine bark amended soil in north central Florida. In the absence of rain, irrigation was applied daily with microsprinklers at ≈120% to 175% of reference evapotranspiration as either single or split applications. Leachate was collected and its volume determined from each lysimeter at 6- to 10-day intervals throughout the study. Water use, expressed as L/plant, was calculated as the difference between the amount of irrigation/rain added to lysimeters and the amount of leachate collected from lysimeters during each measurement period. Average daily water use was calculated for monthly intervals beginning in Apr. 2010 and ending in Sept. 2012. Water use increased rapidly during spring through the final stages of fruit ripening and harvest (May) with peak water use occurring during mid to late summer (July, August, and September). Plants grown in pine bark beds used more water than plants in pine bark amended soil during Apr., May, and Dec. 2010, Feb. 2011, and Mar. 2012, but there were no differences during the periods of highest water use. No differences in water use were observed between single or split-application irrigation treatments. Monthly averages for daily water use during the 30-month period ranged from ≈1.75 L/plant in January to ≈8.0 L/plant in mid to late summer. Mean monthly crop coefficient values during the 30-month period ranged from 0.44 in February to 0.86 in September. Canopy volume, yield, and mean berry weight were unaffected by soil or irrigation treatments.

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