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Use of growth regulators in ornamental plant production is a common nursery practice. Research conducted in determining landscape establishment of herbaceous plants treated with various concentrations of growth regulators is limited. The first phase of this study was conducted to evaluate response of three herbaceous ornamental species to application of ethephon. Containerized plants of irish moss, scotch moss, and salvia were treated once with FLOREL® (ethephon) at 0, 250, 500, or 750 ppm 2 weeks after transplanting into #1 size containers. During the course of the 6-week production period, standard nursery practices of fertigation, pest control, and weed management were followed. Data were collected on growth indices and marketable quality ratings (scale of 1–5) every 2 weeks. Mean initial and final shoot and root dry weights were calculated at the start and end of this phase of the experiment. The experimental design was completely randomized and data analyses were made using the analysis of variance with SAS general linear model procedure. Growth indices (cm) were significantly affected by increasing concentrations of FLOREL®. At 750 ppm concentration the mean growth indices were low (2516 cm) whereas, control (0 ppm) produced the highest mean growth indices (4317 cm). Significant differences in marketable quality ratings were also observed among the treatments where control (0 ppm) plants had the best mean rating (4.3) as compared with 500 ppm (3.6) or 750 ppm (3.5) concentrations. Salvia produced mean growth indices and mean width of 9106 and 513 cm, respectively. However, irish moss had asignificantly higher mean quality rating (4.4) when compared with either salvia (3.7) or scotch moss (3.3).
Slow-release fertilizers (SRF) are greatly used in container production in addition to an hebdomadal fertigation regime. For economic and environmental motives, growers wish to restrict fertigations. The objectives of this paper are to characterize the release patterns of several SRF and to determine the benefits of these fertilizers on the growth of selected woody ornamental plants. The SRF used in this study were: Osmocote®, Nutricote®, Polyon®, Nutralene® and Woodace®. The two first parts of the study were conducted in a greenhouse in Marsh 1993, with Weigela florida `Rumba' in the first part and without plant in the second one. Fertilizers were top dressed according to a medium suggested concentration. The third part of this study was done in the field in June 1993, with the same fertilizers applied in three concentrations as follow: low suggested concentration (SC), 1.5× SC and 2× SC. Two species were tested in this part, Weigela florida `Rumba' and Spiraea bumalda `Goldflame'. Growth was measured by the height of the plant, the width of canopy and the dry mass of leaves, stems and roots. Samples leachate were collected weekly or monthly for greenhouse and field studies respectively. Leachates were analysed for their mineral content per dry mass of plant tissue and the results will be presented on the poster. In the third study, plants gave a comparable growth with the first and the third fertilizer concentrations.
The objective of this study is to determine the phytotoxicity and efficiency of oxadiazon and sethoxydim used as herbicide in the production of four species of woody ornamental plants grown in containers. Four species were used: Cornus alba `Argenteo Marginata', Weigela florida `Rumba', Prunus x cistena and Thuja occidentalis `Woodwardii'. Six herbicide treatments were used (oxadiazon at 0,4 and 8 Kg (a.i.)/ha; sethoxydim at 0.000, 0.276 and 0.552 Kg (a.i.)/ha) and two controls were added (weeding and unweeding). The eight treatments were included in a complete block design replicated six times. This project was started in July 1993 and was conducted for three months. If phytotoxic symptoms were present on plants they were recorded and their effects on growth was measured. At the end of the experiment, weeds present in pots were identified, counted and their growth measured. Preliminary results showed that oxadiazon applied at rates of 4 and 8 Kg (a.i.)/ha had a good efficiency weed control in container production. Sethoxydim applied at rates of 0.276 and 0.552 Kg (a.i.)/ha had a good grass control. The two herbicides did not show phytotoxic symptoms on the for species used. The effects of herbicides on plant growth will be presented.
144 POSTER SESSION (Abstr. 547–556) Container Production–Woody Ornamentals/Landscape
Abstract
The present high cost of maintenance is a key factor in every sector of landscape industry. Weed control is a particularly expensive aspect of maintenance and land managers constantly are seeking more effective methods of control. Since soil cultivation is laborious and expensive, herbicides and mulches are becoming popular in many countries. In contrast to herbicides, which have become widely used in ornamentals only in the past 20 years, mulching has been used for centuries.
Compost has great potential for use in horticulture; however, the relationship between compost feedstock materials and resultant compost characteristics must be well understood. Research examining plant growth response from the addition of compost to container growing media is limited. This research had two parts: the first part examined the relationship between compost feedstock materials and resultant mature compost characteristics. The second part investigated plant growth responses when compost replaced the peat component of container growing media. Two feedstock treatments were aerobically composted in turned windrows. Compost characteristics examined include pH, EC, C:N Ratio, Solvita Maturity, and several biological characteristics (total and active bacteria, total and active fungi, protozoa, spore forming bacteria, E. coli O157:H7, and total coliformic bacteria). To examine plant growth response, compost was substituted for peat (from 0%-40% by total volume) in container growing media. Crops tested were Antirrhinum majus `Rocket White', Viola × wittrockiana `Crown Azure', Oriental Hybrid Lilium `Siberia', and Chrysanthemum × grandiflorum `Yellow Kodiak'. Quantitative plant growth response measurements (shoot fresh and dry weight, percent root necrosis, flower number, and flower size) were recorded and compared by treatment. Despite initial feedstock differences between the two compost treatments, both resulted in similar compost biology and species richness. Coliformic bacteria and E. coli O157:H7 levels were below detection limits in final compost. Choice of compost feedstock materials had a significant effect on the chemical characteristics of the finished product. Compost replacement for peat resulted in plant growth greater than or equal to those of the control treatment.
The Univ. of Connecticut has designed a website that will help facilitate the learning of landscape plant material. The main objective of this site is to help students taking plant identification courses in New England's land-grant universities and one private college. Virtual Campus Plant Walks have been developed to address budget constraints, student demands for technology integration in the classroom and to make use of the pedagogical benefits of the internet medium. The Virtual Campus Plant Walks are on-line walks that have detailed pictures and information given during actual plant walks done in each plant identification laboratory. Students are able to retake the walks at their own pace, reevaluate a plant they are having trouble remembering, or take the walk over the internet for the first time if they were unable to attend lab. Students will now be able to study plant material whenever they want, regardless of the time of day or weather. The educational validity of the walks has been tested for three semesters and the results are favorable. Surveys reveal that 80% believe the website improved their grades and 76% claimed the website decreased their study time. This evidence will promote the continued and expanded use of the website.
99 ORAL SESSION (Abstr. 558-565) WOODY PLANT STRESS PHYSIOLOGY
Abstract
Shoot tip explants of 12 woody species and cultivars of Rosaceae were cultured in vitro on Linsmaier and Skoog nutrient medium containing benzylamino purine (BA). Greatest shoot proliferation occurred in the presence of 0.1 to 2.5 mg/liter BA and was species-dependent. Root initiation was promoted when 1 to 10 mg/liter indolebutyric acid (IBA) was added to the medium. Rooting increased when cultures were incubated in the dark for 1 week prior to illuminated incubation.
Abstract
The citrus whitefly, Dialeurodes citri (Ashmead), prefers Gardenia jasminoides Ellis cv. August Beauty to G. jasminoides cv. Radicans, Viburnum odoratis- simum Ker-Gawl, and Ligustrum sinense Lour. cv. Variegata for egg deposition. Mean numbers of citrus whiteflies found in subsequent life stages (after the egg) remained significantly higher on G. jasminoides cv. August Beauty. These four host plants of the citrus whitefly are major production and landscape items in the south; therefore, segregation of cultivars most heavily infested by the pest is an important consideration when planning control strategies.