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In nursery production, increased branching is desirable, especially when growing stock that will be marketed at smaller sizes. Typically, branching is increased by pruning, which reduces growth potential. As an alternative to mechanical pruning, a chemical branching agent, Cyclanilide, has been evaluated for its ability to increase branching in container-grown whip production systems. Cyclanilide sprays of 0, 50, 100, and 200 mg·L-1 were applied to elongating shoots of Acer ×freemanii `Jeffsred', Cercis canadensis, Diospyros virginiana, Eucommia ulmoides, Malus ×`Prairie Fire', Malus ×`Harvest Gold', and Quercus rubra whips. Branching was increased in all taxa except Eucommia at concentrations >100 mg·L-1, without significantly reducing plant dry weight. For Diospyros, branching was increased when combined with pruning before Cyclanilide application.

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Effect of cutting age (weeks after budbreak) and K-IBA concentration on percent rooting of Mexican redbud [Cercis canadensis var. mexicana (Rose) M. Hopkins], larchleaf goldenweed [Ericameria laricifolia (Gray) Shinners], littleleaf ash (Fraxinus greggii Gray), and evergreen sumac (Rhus virens Gray) were investigated. For cuttings treated with K-IBA, maximum predicted percent rooting from regression analysis was 88% for cuttings of Mexican redbud taken 4 weeks after budbreak and treated with 21 g·liter-1, 99% for larchleaf goldenweed taken 6 weeks after budbreak and treated with 16 g·liter-1, 86%, for littleleaf ash taken 16 weeks after budbreak and treated with 17 g·liter-1, and 24% for cuttings of evergreen sumac taken 16 weeks after budbreak and treated With 5 g·liter-1. Chemical names used: potassium salt of 1H-indole-3-butanoic acid (K-IBA).

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Rooting experiments have been conducted with a pink flowered redbud (Cercis canadensis) in anticipation of its release to the nursery trade. Cuttings taken in May, June and August were treated with NAA or IBA at 0, 1,000, 10,000 and 20,000 ppm and rooted under mist. Rooting percentages as high as 94% have been obtained by using IBA at 20,000 ppm on cuttings taken 3 weeks after growth began. Fifty percent of cuttings taken in June rooted when treated with the highest IBA rates. Cuttings taken later than June did not root. In a separate test, terminal (semi-hardwood) cuttings making active growth were compared to sub-terminal (hardwood) cuttings. IBA and NAA application at 20,000 ppm resulted in 57% rooting for terminal cuttings while producing only 14% rooting for sub-terminal cuttings. Data will be presented on the comparison of the rooting ability of this clone as compared to seedling trees.

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Abstract

Seed germination was 90–95% for Kentucky coffeetree [Gymnocladus dioicus (L.) C. Koch] after concentrated sulfuric acid treatment for 120 to 150 minutes; 97–98% for honeylocust (Gleditsia triacanthos va. inermis L.) following 60, 90, or 120 minutes concentrated sulfuric acid scarification; and was 67–72% for redbud (Cercis canadensis L.) after 30, 60, or 90 minutes of concentrated sulfuric acid scarification followed by a 60-day stratification period. Scanning electron micrographs of acid-scarified Kentucky coffeetree, honeylocust, and redbud seed indicated that lumens of the macrosclereid cells on the seed surface were exposed after acid treatment, permitting imbibition of water. Boiling water treatment ruptured the macrosclerid layer, while seed treated with liquid N2 had fissures that did not appear to penetrate the macrosclereid layer.

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Many nurseries are using the pot-in-pot (PNP) system to grow trees in containers. This system protects the roots from temperature extremes and prevents tipping. PNP is not without problems, trees with vigorous roots may escape the container and root into the external soil making harvest difficult. PNP has no effect on root circling. Our objective was to determine if a polypropylene fabric disk treated with either trifluralin or copper placed in the bottom of a container would prevent root circling. Cercis canadensis and Quercus shumardii seedlings were grown in 19 liter polyethylene containers with eight root control treatments, which included trifluralin or copper impregnated polypropylene fabric disks placed in the bottom of the containers. Ttifluralin treatments, BioBarrier and trifluralin impregnated fabric, had few roots in the bottom of the containers. Of the copper treatments, Spinout® impregnated fabric was the only copper treatment that had any effect on root development in the bottom of the containers.

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Rockwool plugs were placed in Magenta G-7 boxes (Sigma) and then autoclaved at 121°C for 20 min. Fifty milliliters of cool autoclaved liquid medium was poured into Magenta G-7 boxes in aseptic conditions before microcuttings of Amelanchier, Cercis canadensis, cherry, and apple were transferred. Murashige and Skoog medium (MS, M-5519, Sigma) containing 30 g·L–1 sucrose, and with/out 1 ppm of NAA, pH 5.5 were used in all experiments. All cultures were incubated at 23 ± 1°C under a 16-hour lighting period with a light intensity of about 4000 lux of white fluorescent light. Microcuttings of Amelanchier, Cercis, Apple, and cherry rooted in rockwool plugs in 3 weeks after transfer and were ready to be out-planted in 6 weeks. Out-planted plantlets were leached with tap water and potted in 4-inch pots with Metrolite mix, then, placed in mist bench under 50% shade for 2 weeks before taking to bench with full sun light. The survival was 100%. Conditions and growth rate of rockwool-plug-rooted plantlets were much better than those plantlets rooted in agar medium. Rockwool plug plantlets had 2–3 flushes of growth before dormancy in greenhouse and were ready to be planted in the field or garden in 8 months after out-planting. Using a rockwool plug system simplifies out-planting procedure, produces better plantlets, increases out-planting survival, and greatly shorten time needed from out-planting to field-plantable size. This system is a very useful system for difficult-to-root woody ornamentals.

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Currently, the majority of tree liners used in the Ohio nursery industry are imported, mainly from the West Coast. The Ohio growing season is 156 days, whereas the Oregon season is 225 days. We are developing an Ohio liner production system, utilizing a retractable roof greenhouse (RRG) that extends the growing season. Liners grown in a RRG have shown greater caliper, height, and root and shoot dry weight than those grown outside of a RRG (Stoven, 2004). The objective of this research was to compare the growth of RRG-grown liners, outdoor-grown liners, and West Coast-grown liners when planted in the field. Four tree species [Quercus rubra, Malus `Prairifire', Acer ×freemannii `Jeffersred' (Autumn Blaze®), and Cercis canadensis] were started from either seed or rooted cuttings in early 2003. They were grown in a glass greenhouse and then moved to their respective environments in March (RRG) and May (outside). In Oct. 2003, the Ohio-grown liners were planted in the field at the Waterman Farm of The Ohio State University, Columbus. In Spring 2004, liners from the West Coast were purchased and planted in the same field setting. Caliper and height were measured in June and Sept. 2004. After one season in the field, trees grown from the RRG and outdoor environments resulted in greater height and caliper than the West Coast liners in Malus, Acer, and Cercis. Acer liners from Oregon had a greater increase in height from June to September than those grown outdoors or in the RRG. Quercus liners from the RRG and outdoor environments displayed greater caliper growth and growth in height than those from the West Coast. Across all species, liners grown from the RRG had the greatest increase in caliper growth.

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Specialty crops generate $40 billion in annual sales comprising a significant portion (40%) of total agricultural sales. The diversity of plant material is a limiting factor for new herbicide registration. The IR-4 program facilitates the labeling of new or experimental pesticides for minor use crops. The objective of this experiment was to determine the ornamental phytotoxicity and efficacy of Pendemethalin for selected 1-gallon perennials. Phytotoxicity was evaluated on Armeria maritime, Boltonia, Buddleaia davidii, Cercis Canadensis, Delphinium, Fragaria, Oenothera, Panicum virgatum, Papaver orientale, Phlox subulata, Rudebeckia fulgida, Scabiosa columbara, Schizachyrium scoparium and Sedum spectabile. Herbicide was applied at 1X, 2X, and 4X rates according to IR-4 protocols with a weedy check included. Pendemethalin was applied twice throughout the study, the second spray occurring two months after the first. Visual ratings were taken of efficacy (scale, 0-10) and phytotoxicity (scale, 1-10, 10 = complete kill) at 15 and 45 days after treatment (DAT). Buddleaia displayed symptoms of phytotoxicity at the 4x rate but grew out of the initial effects of the herbicide. By trials end, Oenothera at 1×, 2×, 4× rates, Fragaria and Phlox at 2× and 4× and Canadensis at 4× had significantly reduced plant quality. All remaining species had acceptable plant quality. Efficacy was evaluated following the same protocol as above with a weedy seed check using a 1/8th tsp.mixture of Digitaria sanguinalis, Poa annua, and Senecio vulgaris per 1-gallon pot. Overall no treatment provided an acceptable level of weed control. The herbicide provided little control of Groundsel, was moderately effective in controlling the Bluegrass, and provided 100% control of the Crabgrass.

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Seed scarification and stratification (moist-prechilling) requirements of Mexican redbud [Cercis canadensis var. mexicana (Rose) M. Hopk.] and evergreen sumac (Rhus virens Gray) and the effects of temperature on final percent germination, maximum germination rate, and inflection time (time to maximum germination rate) for the above species plus seeds of mealy sage (Salvia farinacea Benth.) were investigated. Maximum predicted germination from a quadratic response surface was 95% after 62 minutes of concentrated sulfuric acid scarification plus 35 days of stratification for Mexican redbud, and 59% after 52 minutes of scarification plus 73 days of stratification for evergreen sumac. Mexican redbud germinated at 24 to 31C. Predicted optima for final percent germination, maximum germination rate, and inflection time were 100% at 28C, 30% germination per day at 31C, and 4 days at 29C, respectively. Evergreen sumac germinated at 21 to 31C. Final percent germination for this species declined with increasing temperature from a predicted maximum of 52% at 21C, whereas maximum germination rate increased with temperature to a predicted maximum of 69% germination per day at 31C. Inflection time was high at both extremes with a predicted minimum of 10 days at 25C. Mealy sage germinated at 21 to 34C. Predicted optima for final percent germination, maximum germination rate, and inflection time were 96% at 25C, 104% germination per day at 27C, and 3 days at 28C, respectively.

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Redbud (Cercis canadensis) is known to be very susceptible to injury by road de-icing salts. The purpose of these experiments was to measure the effects of sodium chloride on net CO2 assimilation (A), conductance (g), transpiration (E), and leaf area expansion (LAE) of hydroponically grown redbud seedlings. Eight week-old seedlings were exposed to 0, 4500, and 9000ppm NaCl in the hydroponic growth solution. A, g, E, and LAE were measured for seven consecutive days during treatment application.

A, g, E, an LAE all decreased with increased salt stress. By the seventh day, growth in NaCl at 4500 and 9000 ppm resulted in reductions in A from that that of the control by 34% and 63%, respectively. For the medium treatment, g and E had decreased by 70% over control rates, and by 85% over control for the high treatment. For the 0, 4500, and 9000ppm treatments, total leaf area increased by 68%, 46% and 28%, respectively, over the seven days of the experiment.

Further experiments will examine the effect of treatments on whole plant transpiration, water potential and osmotic potential and will measure the ability of seedlings to recover from treatments of various duration.

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