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David Vandergriff and Willard T. Witte

Fifteen-cm terminal cuttings of llex × `Nellie R. Stevens' were harvested 28 Nov. 1993. Basal leaves were stripped with five to six terminal leaves remaining. Groups of 10 cuttings were treated with a 5-s quick-dip by inserting stem bases to a depth of 2.5 cm into the treatment solution. Treated cuttings were immediately inserted into 12-cm-deep nursery flats containing moist 40% Pro-Mix/60% perlite. Hormone treatments were dilutions of Dip'N Grow formulation (10,000 ppm IBA + 5000 ppm NAA). IBA/NAA levels were set at 3000, 6000, and 9000 ppm and combined in a factorial arrangement with penetrating agents of 20% dimethylformamide and 20% triethanolamine with water as a control for nine treatment combinations. Ten replications were placed on a propagation bench with bottom heat (25C) and intermittent mist. When most cuttings were well-rooted, each cutting was rated on a scale of 1 (no or little rooting) to 5 (heavy rooting). Analysis of variance showed each level of rooting hormone to be different from every other level, with best rooting at 9000 ppm (3.80). Penetrating agent treatments were different from each other, with best rooting in triethanolamine treatments (3.54), followed by dimethylformamide treatments (3.29), and controls (2.65).

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Randon J. Krieg and Willard T. Witte

Tap roots of two coarse rooted species, Nyssa sylvatica and Quercus acutissima, were subjected to six treatment materials which were cut to fit or placed on the bottom of a 7.61 container. Each treatment material (paint only, Styrofoam plug tray, 3M floor buffer mat, peat fiber sheet, stone and weed barrier fabric) was either painted with Spin Out™ of impregnated with Spin Out™ WP. Treatments that allowed the tap root to penetrate the material, i.e. weed barrier fabric, stone and 3M floor buffing mat, were more effective in controlling tap root elongation. The weed barrier fabric significantly reduced tap root length of Quercus acutissima and Nyssa sylvatica by 80% and 67% respectively compared to controls and by 65% and 53% respectively compared to the paint only treatment. In some cases the 3M and stone treatments were more effective than the weed barrier fabric but were impractical because of weight or expense.

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Willard T. Witte, Scott Schlarbaum, Roger Sauve, and Phillip C. Flanagan

Since 1988, efforts have been underway to establish a nursery research station in McMinnville, Warren County, Tennessee. Approximately 80 acres of farm property adjacent to the Collins scenic river has been conveyed to Tennessee State University (TSU) for this purpose. Scientists at TSU, Tennessee Technological University, University of Tennessee, and USDA's National Arboretum and Shade Tree Laboratory have cooperated in obtaining grant funds via the Capacity Building Grants Program to initiate a plant evaluation and introduction program. Replicated trials of woody genera include Acer, Castanea, Cornus, Lagerstroemia, Quercus, Syringa, Ulmus. Herbaceous genera are Echinacea, Hemerocallis, Hosta. Plantings will be made over a three year period as infrastructure at the new station develops. Additional grant proposals have been recently submitted.

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Phillip C. Flanagan, Roger Sauve, and Willard T. Witte

The Tennessee State University Nursery Crops Research Station is located at McMinnville in Middle Tennessee. This is a major nursery production area with a USDA Zone 6b climate and 134 cm mean annual rainfall.

Approximately 4 ha has been established, with drip irrigation, for comparative evaluation trials of Acer, Cornus, Lagerstroemia, Quercus, Syringa and Ulmus. Plants are being evaluated for: 1) landscape performance - growth, drought tolerance, heat/cold tolerance, 2)ornamental characteristics - bloom. leafcolor, fall color, shape, 3) resistance to disease and pests, and 4) adaptability for production under commercial conditions. Acquisition of plant materials began in 1992 with the collection and planting of more than 120 spp/cv of Acer. Plantings in 1994 consisted of Cornus = 100 spp/cv; Lagerstroemia = 70 spp/cv; Quercus ≈ 90 spp/cv; Syringa ≈ 50 spp/cv and Ulmus ≈ 30 spp/cv.

The long term objective is the establishment of a comprehensive evaluation program for the nursery industry of Tennessee.

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Mark J. Arena, Otto J. Schwarz, and Willard T. Witte

Aqueous diffusates of either Salix erythroflexus (contorted willow) or Robinia pseudoacacia (black locust) were tested as a root-promoting substance on woody plants and Vigna radiata (mung bean). On 8 July 1995 water diffusates were prepared from fresh chopped terminal stems of either willow or locust (680 g) that were steeped in 4 liters of water for 24 hours. Semihardwood cuttings of Chionanthus retusus were double wounded, steeped in either willow, locust, or water for 24 hours followed by a treatment with 3.0% IBA in talc. One additional group of cuttings was treated with 3.0% IBA only. After 75 days, cuttings treated with willow diffusate and IBA produced the greatest number of roots, followed by the locust diffusate and IBA treatments. A similar test using willow diffusate and IBA on softwood cuttings of Chionanthus virginicus resulted in an 80% success rate. A modified mung bean bioassay was used to partially characterize and verify the effects of the diffusates. Diffusates were made from chopped frozen locust or willow terminal stems (10 g/300 ml H2O), stirred for 24 hours. Mung bean cuttings treated with either locust or willow diffusate (5 ml/10 ml H2O) plus 80 ppm IBA produced more roots than IBA or either diffusate alone. A dose response test showed a significant increase in rooting as concentrations increased (H2O,10%, 50%, 75%, and 100%) for both diffusates. Ethyl acetate extractions of each diffusate at pH 3.0 produced more roots than extracts at pH 7.0. A thermal stability test (20 min at 100 °C) on the diffusates showed willow maintained its root-promoting activity, while locust did not.

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Willard T. Witte, Scott Schlarbaum, Roger Sauve, and Phillip C. Flanagan

Efforts have been underway since 1988 to establish a nursery research station in McMinnville, TN. Approximately 80 acres of farm property has been conveyed to Tennessee State University (TSU) for this purpose. Scientists at TSU, Tennessee Technological University, University of Tennessee, and USDA's National Arboretum and Shade Tree Laboratory have cooperated in obtaining funding via the Capacity Building Grants Program to initiate a plant evaluation and introduction program at the new station. Initial trials of woody genera include Acer, Castanea, Cornus, Lagerstroemia, Quercus, Syringa, and Ulmus. Herbaceous genera are Echinacea, Hemerocallis, and Hosta. Plantings will be made over a three year period as infrastructure at the new station develops. Complementary grant proposals have been recently submitted. Design, funding and support of all Tennessee introduction and evaluation programs will be discussed.

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Anjana R. Sharma, Robert N. Trigiano, Willard T. Witte, and Otto J. Schwarz

Cultivars of flowering dogwood (Cornus florida L.) are commercially propagated by vegetative methods such as rooting cuttings or grafting. The results of these methods can be unpredictable. A reliable method of producing dogwoods through tissue culture would be very useful to rapidly produce many copies of important genotypes with horticulturally important characters such as resistance to diseases. One of the primary difficulties of propagating dogwoods (seedlings only) by axillary bud multiplication has been the low rooting efficiency of the microshoots. Various treatments were tried in order to enhance rooting. Eighty-three percent of microshoots harvested between 5 and 7 weeks and treated continuously with 4.9 micromolar IBA rooted after 4 weeks, whereas <20% of microshoots harvested before 5 weeks and after 7 weeks rooted after 4 weeks of continuous exposure to IBA. Differences were also observed in rooting potentials of microshoots that had reddish brown stems rooting at a higher frequency compared to those that had green stems. We hope to translate this method to the propagation of cultivars and potential new releases.

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Gary L. McDaniel, William E. Klingeman, Willard T. Witte, and Phillip C. Flanagan

One-half (18 g·ha-1 a.i.) and three-fourths (27 g·ha-1 a.i.) rates of halosulfuron (Manage®, MON 12051) were combined with adjuvants and evaluated for effectiveness in controlling purple nutsedge (Cyperus rotundus L.) and for phytotoxic responses exhibited by two kinds of container-grown ornamental plants. Adjuvants included X-77®, Scoil®, Sun-It II®, Action “99”®, and Agri-Dex®. By 8 weeks after treatment (WAT), halosulfuron combined with X-77®, Agri-Dex®, or Action “99”® at the lower halosulfuron rate provided <90% purple nutsedge suppression. In contrast, Sun-It II® provided 100% control when combined with the higher halosulfuron rate. Nutsedge control persisted into the following growing season and halosulfuron combined with either Scoil® or Sun-It II® provided >97% suppression of nutsedge tuber production. Growth of liriope [Liriope muscari (Decne.) Bailey `Big Blue'] was not inhibited by Scoil® or Sun-It II® adjuvants in combination with the low rate of halosulfuron. However, regardless of the rate of halosulfuron or adjuvant used, initial foliar chlorosis was observed in both daylily (Hemerocallis sp. L. `Stella d'Oro') and liriope. All liriope receiving halosulfuron with X-77®, Scoil®, or Sun-It II® adjuvants recovered normal foliage by 8 WAT. By contrast, at 8 WAT some daylily still maintained a degree of foliar discoloration. In addition to chlorosis, all treatments reduced flower number in daylilies. The number of flower scapes produced by liriope was not affected by halosulfuron when in combination with either Sun-It II® or Scoil®. The high rate of halosulfuron combined with X-77® or Action “99”® improved control of purple nutsedge. However, this rate inhibited growth of both species, daylily flower numbers, and scape numbers of liriope, regardless of adjuvant. Chemical names used: halosulfuron (Manage®, MON 12051, methyl 5-{[(4,6-dimethyl-2-pyrimidinyl) amino] carbonyl-aminosulfonyl}-3-chloro-1-methyl-1-H-pyrozole-4-carboxylate); proprietary blends of 100% methylated seed oil (Scoil® and Sun-It II®); proprietary blend of 99% polyalkyleneoxide modified heptamethyl trisiloxane and nonionic surfactants (Action “99”®); alkylarylpolyoxyethylene, alkylpolyoxyethelene, fatty acids, glycols, dimethylpolysiloxane, and isopropanol (X-77®); proprietary blend of 83% paraffin-based petroleum oil, with 17% polyoxyethylate polyol fatty acid ester and polyol fatty ester as nonionic surfactants (Agri-Dex®)