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In 1991, a cooperative project with the U.S. National Arboretum in Washington, D.C., was initiated in Tifton, Ga. (USDA hardiness zone 8a) to evaluate red maples (Acer rubrum L.) potentially suitable for the coastal plain region of the southeastern U.S. Greatest annual height growth across all cultivars over 6 years was for `Alapaha', a seedling selection from southern Georgia with annual height growth of 35 inches (88.0 cm), and several seedling selections from northern Florida with annual height increases in excess of 33 inches (86.0 cm). Selections showing the least average annual height growth were NA-56024 and NA-57772 (`Red Rocket'). For commercially available cultivars, the most dependable for fall color in Tifton was `October Glory'®. In addition, two new selections from the National Arboretum have also shown excellent fall color—`Somerset' and `Brandywine'.

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Heller’s japanese holly [Ilex crenata ‘Helleri’ (synonym: Ilex crenata f. helleri)] is a popular landscape plant in U.S. Department of Agriculture hardiness zones 5b to 8a because of its dwarf habit, slow growth rate, and dark green leaves. Plants can be propagated readily by stem cuttings and use of an auxin treatment is generally recommended to promote rooting. This study was conducted to determine if auxin treatment could be eliminated, thus reducing labor and chemical requirements in the cutting propagation process. In three experiments, terminal stem cuttings of Heller’s japanese holly were taken in winter, prepared both with and without use of a basal quick-dip in an auxin solution [2500 ppm indole-3-butyric acid (IBA) + 1250 ppm 1-naphthaleneacetic acid (NAA)], and rooted in a warm, high-humidity environment. Both nontreated cuttings and cuttings receiving a 1-second basal quick-dip in the auxin solution rooted at, or near, 100%. However, treatment of cuttings with auxin resulted in larger root systems on the rooted cuttings, which could allow earlier transplanting into larger nursery containers. No inhibition of new spring growth was exhibited by cuttings treated with auxin in comparison with nontreated cuttings.

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‘Dwarf Burford’ holly (Ilex cornuta ‘Dwarf Burford’) is a significant nursery crop and is widely used in landscapes in U.S. Department of Agriculture hardiness zones 7 to 9. Stem cuttings can be rooted at multiple times during the year, provided cutting wood is sufficiently mature, with auxin treatments traditionally used to encourage rooting. This study was conducted to determine if auxin treatment could be eliminated, thus reducing labor and chemical requirements in the cutting propagation process. In three experiments, terminal stem cuttings of ‘Dwarf Burford’ holly were taken in winter, prepared with and without use of a basal quick-dip in an auxin solution, and rooted in a warm, high-humidity environment. Rooting percentages for nontreated cuttings and cuttings treated with 2500 ppm indole-3-butyric acid (IBA) + 1250 ppm 1-naphthaleneacetic acid (NAA) were similar, while treatment of cuttings with 5000 ppm IBA + 2500 ppm NAA resulted in a decrease in rooting percentage. The number of primary roots and total root length were similar among the three treatments, except in one experiment where total root length was greater with auxin-treated cuttings than with nontreated cuttings. Initial shoot growth responses were variable among the three experiments. The treatment of cuttings with auxin was not required for successful rooting and can be eliminated from the process for winter stem cutting propagation of ‘Dwarf Burford’ holly.

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Acer rubrum `October Glory' has grown well in field studies across the southeastern United States. However, there is limited information on container production for this cultivar. Our objective was to evaluate first-year growth of container-grown `October Glory' at three locations with dissimilar climates in Georgia and Alabama. Rooted cuttings were planted in no. 3 containers at one location in Apr. 1995. Trees were transported the second week of June to Blairsville, Ga.; Auburn, Ala.; and Tifton, Ga. Trees were grown for 6 months until dormant and were harvested at the end of December. Location had no impact on final plant height increase (Blairsville, Auburn, and Tifton, 59.8, 53.0, and 60.2 cm, respectively). Increases in stem diameter and shoot dry mass were greatest at Tifton (8.4 mm, 17.5 g) and least at Blairsville (6.3 mm, 9.2 g), with Auburn similar to both locations (6.8 mm, 12.2 g). Root dry masses and root: shoot ratios were greatest in Tifton (17.2 g, 0.967), with no differences between Blairsville (4.9 g, 0.508) and Auburn (7.0 g, 0.641). Despite climatic dissimilarities, among locations, producers of container-grown `October Glory' could expect similar growth during the first year throughout Georgia and Alabama.

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A study evaluating the effects of varying levels of chilling on foliar budbreak of linden (Tilia spp.) culivars was initiated in 1999 in Auburn, Ala. [lat. 32°36'N, long. 85°29'W, elevation 709 ft (216m), USDA Hardiness Zone 8a]. Littleleaf linden (T. cordata) `Greenspire' and `Fairview' required the most chilling to produce measurable budbreak and exhibited the lowest budbreak percentages. Silver linden (T. tomentosa) `Sterling' and american linden (T. americana) `Redmond' needed the fewest hours of chilling to produce budbreak and exhibited the highest budbreak percentages. `Sterling' was the top performer in foliar budbreak percentage and in subsequent growth. Although `Redmond' attained high budbreak numbers, its overall growth during the following growing season was inferior to that of `Sterling', `Greenspire' and `Fairview'. This information can contribute to the development of regional planting recommendations, which can aid in the selection of lindens suitable for the area in which they will be grown. Calculated r2 values indicated the models used provided a good fit to the data for all cultivars.

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The unprecedented, yet sustained, growth of undergraduate enrollment in the Department of Horticulture at Auburn University can be attributed to many factors, including an increased industry demand for horticulture graduates nationwide. Perhaps the basis of some of Auburn's growth, while appearing to be unique, may be of value in other programs. This paper chronicles the growth of the Auburn Department of Horticulture undergraduate program and highlights some of the traditional teaching methods employed within the department as well as some unique methods that contribute to the program. The paper offers ideas and practices that may be beneficial to other horticulture programs and may encourage teaching faculty at other institutions to publish similar departmental profiles that may prove beneficial to colleagues.

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The influence of three shade levels on propagation of golden barberry (Berberis koreana Palib. × B. thunbergii DC.) selection `Bailsel' was evaluated in studies initiated 29 Apr. and 18 Sept. 1998. After 57 days, root ratings were higher in plants under 70% and 80% shade treatments than 60% shade for both studies. In study one, viability was lower among plants under the 60% shade level than those under 70% or 80% shade levels. Viability among treatments was similar in study two. Based on visual observations, leaf retention appeared greater under the 70% and 80% shade treatments than the 60% shade treatment for both studies. Cuttings rooted under 70% and 80% shade levels generally had a uniform golden hue, whereas the foliage of those rooted under 60% shade often had a red hue and showed signs of desiccation for both studies. Root dry weights were greater for cuttings under the 60% shade levels than 70% or 80% shade.

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In five experiments, singlenode cuttings of `Red Cascade' miniature rose (Rosa) were treated with a basal quick-dip (prior to insertion into the rooting substrate) or sprayed to the drip point with a single foliar application (after insertion) of Dip `N Grow [indole-3-butyric acid (IBA) + 1-naphthaleneacetic acid (NAA)], the potassium salt of indole-3-butyric acid (K-IBA), or the potassium salt of 1-naphthaleneacetic acid (K-NAA); a single foliar spray application of Dip `N Grow with and without Kinetic surfactant; or multiple foliar spray applications of Dip `N Grow. Spray treatments were compared with their respective basal quick-dip controls {4920.4 μm [1000 mg·L-1 (ppm)] IBA + 2685.2 μm (500 mg·L-1) NAA, 4144.2 μm (1000 mg·L-1) K-IBA, or 4458.3 μm (1000 mg·L-1) K-NAA}. Cuttings sprayed with 0 to 246.0 μm (50 mg·L-1) IBA + 134.3 μm (25 mg·L-1) NAA, 0 to 207.2 μm (50 mg·L-1) K-IBA, or 0 to 222.9 μm (50 mg·L-1) K-NAA resulted in rooting percentages, total root length, percent rooted cuttings with shoots, and shoot length similar to or less than control cuttings. Exceptions were cuttings sprayed with 0 to 2.23 μm

(0.5 mg·L-1) K-NAA, which exhibited shoot length greater than the control cuttings. Addition of 1.0 mL·L-1 (1000 ppm) Kinetic organosilicone surfactant to spray treatments resulted in greater total root length and shoot length. Repeated sprays (daily up to seven consecutive days) had no or negative effects on root and shoot development.

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The objective of this study was to evaluate the potential for use of container substrates composed of processed whole pine trees (WholeTree). Three species [loblolly pine (Pinus taeda), slash pine (Pinus elliottii), and longleaf pine (Pinus palustris)] of 8- to 10-year-old pine trees were harvested at ground level and the entire tree was chipped with a tree chipper. Chips from each tree species were processed with a hammer mill to pass through a 0.374-inch screen. On 29 June 2005 1-gal containers were filled with substrates, placed into full sun under overhead irrigation, and planted with a single liner (63.4 cm3) of ‘Little Blanche’ annual vinca (Catharanthus roseus). The test was repeated on 27 Aug. 2005 with ‘Raspberry Red Cooler’ annual vinca. Pine bark substrate had about 50% less air space and 32% greater water holding capacity than the other substrates. At 54 days after potting (DAP), shoot dry weights were 15% greater for plants grown in 100% pine bark substrate compared with plants grown in the three WholeTree substrates. However, there were no differences in plant growth indices for any substrate at 54 DAP. Plant tissue macronutrient content was similar among all substrates. Tissue micronutrient content was similar and within sufficiency ranges with the exception of manganese. Manganese was highest for substrates made from slash pine and loblolly pine. Root growth was similar among all treatments. Results from the second study were similar. Based on these results, WholeTree substrates derived from loblolly pine, slash pine, or longleaf pine have potential as an alternative, sustainable source for producing short-term horticultural crops.

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A study was conducted at Auburn University in Auburn, AL, and the U.S. Department of Agriculture–Agricultural Research Service, Southern Horticultural Laboratory in Poplarville, MS, to evaluate clean chip residual (CCR) as an alternative substrate component for annual bedding plant production. Clean chip residual used in this study was processed through a horizontal grinder with 4-inch screens at the site and was then processed again through a swinging hammer mill to pass a 3/4- or 1/2-inch screen. Two CCR particle sizes were used alone or blended with 10% (9:1) or 20% (4:1) peatmoss (PM) (by volume) and were compared with control treatments, pine bark (PB), and PB blends (10% and 20% PM). Three annual species, ‘Blue Hawaii’ ageratum (Ageratum houstonianum), ‘Vista Purple’ salvia (Salvia ×superba), and ‘Coral’ or ‘White’ impatiens (Impatiens walleriana), were transplanted from 36-cell (12.0-inch3) flats into 1-gal containers, placed on elevated benches in a greenhouse, and hand watered as needed. Ageratum plants grown at Auburn had leaf chlorophyll content similar or greater than that of plants grown in PB. There were no differences in salvia; however, impatiens plants grown in PB substrates at Auburn had less leaf chlorophyll content than those grown in CCR. There were no differences in ageratum, salvia, or impatiens leaf chlorophyll content at Poplarville. There were no differences in growth indices (GI) or shoot dry weight (SDW) of ageratum, while the largest salvia was in PB:PM and the largest impatiens were in PB-based substrates at Auburn. The GI of ageratum at Poplarville was similar among treatments, but plants grown in 4:1 1/2-inch CCR:PM were the largest. Salvia was largest in 4:1 CCR:PM and PB:PM, and although there were no differences in GI for impatiens at Poplarville, the greatest SDW occurred with PB:PM. Foliar nutrient content analysis indicated elevated levels of manganese and zinc in treatments containing CCR at Auburn and PB at Poplarville. At the study termination, two of three annual species tested at both locations had very similar growth when compared with standard PB substrates. This study demonstrates that CCR is a viable alternative substrate in greenhouse production of ageratum, salvia, and impatiens in large containers.

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