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E.C. Boehm, T.D. Davis and J.O. Kuti

Relative water usage of four species of container-grown woody ornamental shrubs (Buxus japonica (Japenese boxwood), Leucophyllum frutescens (Texas sage), Ligustrum japonica (ligustrum) and Pittosporum tobira wheeleri (dwarf) pittosporurm)), normally used for home landscaping in south Texas, were evaluated by comparing water consumption and frequency of watering with growth rates and horticultural quality after six months growth in containers. Growth rates were determined by the difference in plant height and leaf area from the control unwatered plants and were used to characterize the suitability of ornamental shrubs for xeric landscapes. While frequency of watering had no significant effects on plant height, only ligustrum and dwarf pittosporum plants watered on weekly basis showed positive change in leaf area. There was considerable leaf regrowth in Texas sage plants after initial leaf loss. Of all the shrubs tested, dwarf pittosporum plants watered biweekly used less water to maintain their horticultural quality.

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Erin Agro and Youbin Zheng

Region-specific trials examining optimum controlled-release fertilizer (CRF) rates for the Canadian climate are limited. This study was conducted to determine an optimum range of CRF application rates and the effect of the application rate on growth, nitrogen (N), and phosphorus (P) losses of six economically important container-grown woody ornamental shrubs using typical production practices at a southwestern Ontario nursery. Salix purpurea ‘Nana’, Weigela florida ‘Alexandra’, Cornus sericea ‘Cardinal’, Hydrangea paniculata ‘Bombshell’, Hibiscus syriacus ‘Ardens’, and Spiraea japonica ‘Magic Carpet’ were potted in 1-gal pots and fertilized with Polyon® 16N-2.6P-10K (5–6 month longevity) incorporated at rates of 0.8, 1.2, 1.7, 2.1, and 2.5 kg·m−3 N in 2012. The experiment was repeated for the 2013 growing season with rates of CRF incorporated at 0.05, 0.35, 0.65, 0.95, and 1.25 kg·m−3 N. Plant performance (i.e., growth index) and leachate electrical conductivity (EC) and pH were evaluated once every 3 to 4 weeks during the respective growing seasons. The amount of N and P lost to the environment was determined for the 2012 growing season. The interaction between nutrient supply rate and target species affected most response variables. Although higher levels of fertilization produced larger plants and had the potential to decrease production time, increased losses of N and P and higher EC leachate values occurred. Results of this study indicate that an acceptable range of CRF application rates can be used for each species depending on the production goals, i.e., decreased production time, maximum growth, or decreased nutrient leachate. Overall, the highest acceptable CRF rates within the optimal range were: 1.25 kg·m−3 N for Spiraea; 1.7 kg·m−3 N for Hydrangea; 2.1 kg·m−3 N for Cornus; and 2.5 kg·m−3 N for Weigela, Salix, and Hibiscus. The lowest acceptable rates within the optimal range were: 0.35 kg·m−3 N for Hibiscus; 0.65 kg·m−3 N for Cornus, Weigela, Salix, and Spiraea; and 0.80 kg·m−3 N for Hydrangea.

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Helen T. Kraus, Stuart L. Warren and Charles E. Anderson

Five ratios of NH4+: NO3-(100:0, 75:25, 50:50, 25:75, and 0:100) were evaluated for impact on growth of Cotoneaster dammeri Schneid. `Skogholm' (cotoneaster), a woody ornamental shrub, and Rudbeckia fulgida Ait. `Goldsturm' (rudbeckia), an herbaceous perennial. Nitrate alone decreased dry weight and leaf area of cotoneaster and rudbeckia compared with mixtures of NH4+ and NO3- and NH4+ alone. Additionally, NO3- alone suppressed accumulation of cationic nutrients and N in cotoneaster, while mixes of NH4+ and NO3- enhanced accumulation of nutrients in roots and shoots of rudbeckia compared with solutions containing either NH4+ or NO3- alone. The steles of roots of cotoneaster and rudbeckia contained more secondary xylem with larger tracheary elements with a mix of 25 NH4+: 75 NO3- than with NO3- alone.

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A.L. Shober, C. Wiese, G.C. Denny, C.D. Stanley and B.K. Harbaugh

Concerns over the environmental impact and economics of harvesting sphagnum and reed-sedge peat have increased the desire to identify acceptable peat substitutes for use in container substrates. This preliminary study evaluated the use of composted dairy manure solids as a substitute for sphagnum or reed-sedge peat in container substrates for production of woody ornamental shrubs and assessed potential leaching of nutrients. Walter's viburnum (Viburnum obovatum), sandankwa viburnum (Viburnum suspensum), and japanese privet (Ligustrum japonicum) were grown in 3-gal plastic containers with seven substrates containing (by vol.) 60% pine bark, 10% sand, and 30% sphagnum peat (S), reed-sedge peat (R), and/or composted dairy manure solids (C). Substrate composition had no effect on plant quality ratings for any species, growth index (GI) of walter's viburnum, or shoot and root dry weight of walter's viburnum and japanese privet. However, the GI of japanese privet and sandankwa viburnum was the lowest when grown in substrates containing a high percentage of reed-sedge peat (0S:3R:0C). Substrate effects on average nitrate + nitrite nitrogen leachate losses were minimal over the 88-day leachate collection period. However, the substrate containing the highest proportions of composted dairy manure solids (0S:0R:3C) generally had the highest average ammonium nitrogen and dissolved reactive phosphorus losses compared with other substrates. All substrates tested as part of this study appeared to be commercially acceptable for production of container-grown woody ornamental shrub species based on growth and quality. However, average nutrient losses from containers differed depending on the peat or peat substitute used to formulate the substrates.

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G. Stephen Crnko, Edward W. Bush and Allen D. Owings

A study was initiated to determine the effects of fall fertilization, specifically N application rate and additions of supplemental K on the production of woody ornamental shrub species. The influence of two slow-release sources of K (4- and 8-month) in the form of K2SO4, three K application rates (0, 1, 2 lb/yd3), and four incorporated application rates of N (0, 1, 2, and 3 lb/yd3) from Osmocote Plus+ 15-9-11 were evaluated on the growth of `Fisher Pink' Indian azalea, glossy abelia, and `Tuscarora' crape myrtle. Growth of `Fisher Pink' azalea, as determined by shoot height and shoot width, increased as N rate increased from 1 to 3 lb/yd3 when compared to the control. The resulting growth index improved at the 2 and 3 lb/yd3 N rate when compared to the 0 and 1 lb/yd3 N rates. Height and width of glossy abelia at the 1 lb N rate with or without supplemental K applications increased when compared to some glossy abelia at the 3 lb N rate (primarily those with supplemental K). Glossy abelia at the 2 lb/yd3 N rate with 2 lb/yd3 N from 4-month 0-0-46 had significantly greater shoot dry weight when compared to the 3 lb/yd3 N rate with 2 lb/yd3 N from 8-month 0-0-46. The 1 to 3 lb/yd3 N application rate had more of a response on growth index, visual quality, and visual color on `Tuscarora' crape myrtle as compared to the 0 lb/yd3 N rate. In this study, the potential influence of supplemental K applications on plant growth was mostly evident for glossy abelia at the 2 lb/yd3 N rate and was not evident on azalea or crape myrtle.

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Derald Harp, Gaye Hammond, David C. Zlesak, Greg Church, Mark Chamblee and Steve George

high-quality roses, crepe myrtle ( Lagerstroemia sp.), perennials, and annuals ( Chretien and Harp, 2017 ; Church et al., 2012 ; Harp et al., 2009 , 2017 ; Zlesak et al., 2015 ). Even though roses remain the most popular woody ornamental shrub in

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Diane Feliciano Cayanan, Youbin Zheng, Ping Zhang, Tom Graham, Mike Dixon, Calvin Chong and Jennifer Llewellyn

, whereas we used woody ornamental shrubs. Differences in results can also be explained by differences in the frequency of exposure to free chlorine treatments. Our plants were exposed to free chlorine on a daily basis, which followed a typical nursery

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Raul I. Cabrera, James E. Altland and Genhua Niu

precipitation, rely also on primary surface water sources with better (less saline) quality, or both. The irrigation quality parameters of the two Texas MRW are slightly to moderately undesirable, higher than those recommended for typical woody ornamental shrubs

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Tim R. Pannkuk

ornamental shrubs based on vegetative coverage of the lysimeter surface. Plant combinations are defined in Table 2 . Plant installation occurred on 12 May 2011 without disturbing sensors and sensor cables. St. augustinegrass was sod grown (All Seasons

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Amanda J. Taylor, R. Thomas Fernandez, Pascal Nzokou and Bert Cregg

days) reduced water use of woody ornamental shrubs in 10-L containers by 6% to 75% without affecting plant growth. Previous studies testing cyclic irrigation on broadleaf woody ornamentals have attributed the resulting increase in growth to cumulative