Poster Session 47—Ornamental/Landscape and Turf 2 21 July 2005, 12:00–12:45 p.m. Poster Hall–Ballroom E/F
Christina Wells, Karen Townsend, Judy Caldwell, Donald Ham, E. Thomas Smiley, and Michael Sherwood
Raul I. Cabrera and Diana Devereaux
Ilex opaca and Lagerstroemia indica plants were grown over 9 months using complete nutrient solutions differing in N concentration [(N)A: 15, 30, 60, 120, 210 and 300 mg·L–1]. Biomass production increased as (N)A were raised from 15 to 60 mg·L–1, but was depressed by higher concentrations. Increases in (N)A produced higher shoot: root ratios. Maximum leaf N concentration was observed at 60 mg·L–1, with similar values at higher (N)A. Plant survival, establishment and performance was evaluated over 15 weeks following transplant (15 WAT) to a landscape with minimum management conditions. Despite the initial significant differences in growth, shoot: root ratios and plant N status, plant establishment was not affected following transplant. Plant characteristics changed significantly over time, and by 15 WAT, all of the measured variables were statistically the same across all treatments. Flowering was, however, delayed over several weeks for Lagerstroemia indica plants grown at the higher (N)A. Analysis of these results indicate that plant production under relatively low N levels in the nursery maximizes N fertilizer use efficiency without affecting landscape establishment and performance.
Peter M. Shaw
A low-cost interactive computer program was designed to assist in teaching landscape plant material classes or any other class that could benefit from the use of computer graphics. The program was written in HyperCard to be used on any Macintosh computer. To illustrate the morphology and to assist in learning the terminology required to identify plants, a dichotomous keying system incorporating computer graphics was developed to lead the student through an interactive lesson. In the process of keying out plants, the student encounters the terminology associated with the groups of plants during the lesson. The student is introduced to plant groups, the terminology, and the concept of the classification process in one interactive lesson.
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.
W. Jack Rowe II, Daniel A. Potter, and Robert E. McNiel
Twenty-six purple- or green-leaved cultivars representing 12 species of woody landscape plants were evaluated in the field for defoliation by Japanese beetles (Popillia japonica Newman) over three growing seasons. We further evaluated the hypothesis that, within closely-related plants, purple cultivars generally are preferred over green ones by comparing beetles' consumption of foliage in laboratory choice tests and their orientation to painted silk tree models baited with Japanese beetle lures. Cultivars of Prunus cerasifera Ehrh. and hybrids of that species [e.g., Prunus ×cistena (Hansen) Koehne, Prunus ×blireiana André] were more heavily damaged than nearly all other plants tested. Among maples, Acer palmatum Thunb. `Bloodgood' and A. platanoides L. `Deborah' and `Fairview' were especially susceptible. None of the cultivars of Berberis thunbergii DC, Cercis canadensis L., Cotinus coggygria Scop., or Fagus sylvatica L. were heavily damaged, regardless of foliage color. In the choice tests, purple Norway maples were preferred over green ones in three of four comparisons, but preference varied within the other plant genera. In fact, more beetles oriented to green-leaved tree models than to purple ones. Our results indicate that within a genus, purple-leaved plants do not necessarily sustain more damage than green-leaved ones. Widespread use of certain purple-leaved cultivars of generally susceptible plant species probably contributes to the perception that purpleleaved plants, overall, are preferred. Purple-leaved cultivars of redbud, European beech, smoketree, and barberry, or the purple-leaved Prunus virginiana L. `Canada Red' or Malus ×hybrida Lemoine `Jomarie' may be suitable substitutes for more susceptible purple-leaved plants in landscapes where Japanese beetles are a concern.
Lin Wu, Janquo Chen, Hong Lin, Phillip Van Mantgem, M. Ali Harivandi, and James A. Harding
The effects of regenerant wastewater irrigation and high concentrations of Ca2+, K+, Mg2+, and Cl– on growth and ion uptake of nine species of landscape plants were studied. Significant differences in chloride tolerance were detected among the species. Generally, the species that had greater uptake of chloride grew less than species that took up less amounts of chloride. Lace fern (Athyrium filix-femina Roth.) had the highest tissue Cl concentration and was the most affected. Hydrangea (Hydrangea macrophylla Ser.) also had high tissue Cl concentration, but showed no growth reduction. Its tolerance was attributable to a high tissue Ca concentration. The data suggest that in the species tested, higher tissue Ca concentrations were positively correlated with plant tolerance to Cl. Overall, the Cl– concentration in the wastewater seems to be the factor most likely to create problems for the landscape plants. However, severe negative effects will probably be noticed only for very sensitive plant species, but it is important to determine this before applying regenerant irrigation water.
Robert F. Polomski, Milton D. Taylor, Sarah A. White, Ted Whitwell, Stephen J. Klaine, and William C. Bridges Jr.
Commercial nurseries use large amounts of water and nutrients during production cycles. Runoff contaminated with N and P can adversely impact surface and groundwater quality. A 3-year monitoring study of nutrient mitigation by a constructed wetland at a container nursery found nitrogen removal was highly efficient. However, orthophosphate-P removal was highly variable. Partial removal occurred during some months, but net export also occurred. P levels in wetland discharge—between 0.84 and 2.75 ppm—were well above the generally accepted level for preventing downstream eutrophication. Therefore, identifying landscape plants that remediate nutrients, especially P, could be useful in improving constructed wetlands. A 2003 greenhouse study screened commercially available landscape plants for their phytoremediation potential. Among the 17 taxa and 19 cultivars examined were woody shrubs, e.g., Cornusamomum, Myricacerifera`Emperor', and Salix integra `Hakura Nishiki'; herbaceous semiaquatics, e.g., Canna(two cultivars), Colocasia esculenta `Illustris', Rhyncospora colorata, Iris`Full Eclipse', Pontederia cordata `Singapore Pink', and Thalia geniculata `Red Stem'; and floating aquatics, e.g., Myriophyllum aquaticum, Eichhornia crassipes, and Pistia stratiotes. Plants were grown in pea gravel media and kept saturated with one of five concentrations of Hoagland's. Herbaceous and woody plants were harvested after 8 and 13 weeks, respectively. Experiments were replicated twice for each cultivar. The nutrient uptake efficiency was determined for each taxon from the total amount of N and P applied and the biomass dry weight and N and P content.
Jennifer L. Boatright and J. M. Zajicek
135 POSTER SESSION 20 (Abstr. 810-832) Landscape/Ornamentals/Turf: Culture and Management
R.A. Mirabello, A.E. Einert, and G.L. Klingaman
The effects of a mulch material on nutrient availability remain questionable. As organic materials decompose, the increased activity of microorganisms immobilizes nutrients (particularly nitrogen) to preform this process. The decomposition of mulch material and the activity of microorganisms may then compete for nutrients applied to ornamental species in the landscape. To examine this question, four widely available mulch materials (pine bark, cypress pulp, pine straw, and cottonseed hulls) and three fertilizer application methods (granule, liquid, and time release), which were applied either above or below the mulch, were established. Beds with and without mulch cover and no fertilization were established as controls. Marigolds, Tagetes erecta `Hybrid Gold', were planted within the beds. Growth response was found to be greatest in beds with cottonseed hulls. Cottonseed hulls are reported to have a high nitrogen content of their own that may influence less immobilization of nitrogen for decomposition. Beds using pinebark showed significant reduction in plant growth. Fertilization application method also demonstrated significant differences in plant response. The use of a granule fertilizer produced the greatest growth response although initial plant loss was observed in beds using this method. The fast release nature of granule fertilizer and potential toxicity were the suspected reason for this observation. Growth data indicated plant performance was unaffected by fertilizer placement.
Linda B. Stabler and Chris A. Martin
22 ORAL SESSION 1 (Abstr. 428–435) Woody Ornamentals/Landscape/Turf: Physiology & Nutrition Monday, 24 July, 8:00–10:00 a.m