Progress 10/01/01 to 09/20/07
Outputs
OUTPUTS: Japanese silver grass (Miscanthus sinensis) and 14 cultivars were transplanted in northern and southern Florida and evaluated for landscape performance, flowering, growth, and seed viability. All plants survived the 84-week study at both locations with the exception of 'Morning Light', where 22% to 33% of the plants died. In northern and southern Florida, 'Arabesque', 'Adagio', 'Cosmopolitan' and 'Gracillimus' received the highest visual quality ratings on average throughout the entire study, yet other cultivars such as 'Central Park' and 'Silberfeder' performed well but had much narrower windows of peak performance. Cultivars such as 'Little Kitten' and 'Sarabande' performed far better in southern Florida than in northern Florida. Regardless of location, 'Morning Light' and 'Puenktchen' generally did not perform as well as other cultivars. In northern Florida, four consecutive months of very good to excellent flowering (75% to 100% canopy coverage) were observed for 'Adagio', 'Arabesque', 'Cosmopolitan', 'Gracillimus', 'Little Kitten', 'Sarabande', 'Silberfeder', and 'Zebrinus'. However, in southern Florida, peak flowering periods for these cultivars were delayed and generally only lasted for one to two months. On average, plants in northern Florida were larger and produced 2.8 times more flowers than plants in southern Florida. All cultivars produced viable seed with germination of viable seed ranging from 53.6% ('Cabaret') to 100% ('Gracillimus') in southern Florida and from 49.8% ('Arabesque') to 100% ('Adagio', 'Little Kitten', 'Sarabande', and 'Variegatus') in northern Florida. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nursery growers, land managers, extension agents. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
In an effort to curb the use and distribution of invasive plant species, more than 38 botanical gardens, garden clubs, professional societies, and nursery associations have adopted voluntary codes of conduct associated with risk assessment, plant selection, importation, and production of ornamental plants. Research on landscape plants is critical to provide scientific evidence of whether a plant is currently invasive or has great potential to become invasive and to set priorities for developing or promoting sterile cultivars. Results of this study emphasize the importance of cultivar and geographic distinctions in determining the invasive status of a species.
Publications
- Wilson, S.B., G.W. Knox, and L.K. Mecca. 2005. Evaluating fifteen Miscanthus sinensis taxa in north and south Florida. Proc. South. Nurs. Assoc. 50:554-558.
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Progress 10/01/05 to 09/30/06
Outputs
A wild-type selection of heavenly bamboo (Nandina domestica) and ten cultivars were evaluated for plant performance, growth, flowering, and fruiting in north and south Florida. Onset of flowering generally began by March and April in south Florida and 4 to 8 weeks later in north Florida. Fruit was first noted 8 to 16 weeks after most selections began flowering. Landscape performance and fruit production varied widely among taxa and locations. The dwarf selections 'Filamentosa' and 'Firepower' failed to flower or fruit in either location; while the medium-sized selection, 'Moon Bay', did not flower or fruit in south Florida, and the medium-sized selection, 'Gulf Stream', flowered but did not fruit in south Florida. Large-sized selections produced more fruit than did dwarf and medium-sized cultivars. Greater plant survival with generally heavier fruiting was observed in north Florida than in south Florida. In north and south Florida, 'Monum' and 'Compacta' produced more
fruit than did the wild-type selection. Seed viability was fairly consistent among cultivars, ranging from 73 to 86%.
Impacts
In an effort to curb the use and distribution of invasive plant species, more than 38 botanical gardens, garden clubs, professional societies, and nursery associations have adopted voluntary codes of conduct associated with risk assessment, plant selection, importation, and production of ornamental plants. Research on landscape plants is critical to provide scientific evidence of whether a plant is currently invasive or has great potential to become invasive and to set priorities for developing or promoting sterile cultivars. Results of this study emphasize the importance of cultivar and geographic distinctions in determining the invasive status of a species.
Publications
- Wilson, S.B. and G.W. Knox. 2006. Landscape performance, flowering, and seed viability of fifteen Miscanthus sinensis taxa grown in northern and southern Florida. HortTechnology. 24:137-142
- Knox, G.W. and S.B. Wilson. 2006. Evaluating north and south Florida landscape performance and fruiting of ten cultivars and a wildtype selection of Nandina domestica, a potentially invasive shrub. J. Environ. Hort. 24:137-142.
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Progress 10/01/04 to 09/30/05
Outputs
In an effort to curb the use and distribution of invasive plant species, over 38 botanical gardens, garden clubs, professional societies, or nursery associations have adopted voluntary codes of conduct associated with risk assessment, plant selection, importation, and production of ornamental plants. Research on landscape plants is critical to provide scientific evidence of whether a plant is currently invasive or has great potential to become invasive and to set priorities for developing or promoting sterile cultivars. We evaluated 10 cultivars and the species form of heavenly bamboo (Nandina domestica) grown in north and south Florida for 100 weeks. Plant performance and fruit production varied widely among cultivars and location. The dwarf selections 'Filamentosa' and 'Firepower' failed to flower or fruit in either location; while the medium selection, 'Moon Bay', did not flower or fruit in south FL, and the medium selection, 'Gulf Stream', flowered but did not
fruit in south FL. Taxa in north FL generally produced more fruit than in south FL. In north and south FL, 'Monum' and 'Compacta' produced more fruit than the wild type selection. Seed viability was fairly consistent among cultivars, ranging from 73% to 86%. Above average visual quality rankings, good survival, and limited or lacking fruit production of 'Gulf Stream', 'Jaytee', and 'Harbour Dwarf' warrant wider landscape use of these selections in the south FL landscape. Results of this study emphasize the importance of cultivar and geographic distinctions when regarding the invasive status of a species.
Impacts
The overall objective of this study was to evaluate plant performance, growth, flowering, fruit production and seed viability of a heavenly bamboo wild type selection and 10 cultivars planted in south FL (Fort Pierce, USDA zone 9b) and north FL (Quincy, USDA zone 8b). Performance, flowering and fruiting varied among heavenly bamboo cultivars and planting location. Greater plant survival with heavier fruiting was observed in north FL than in south FL. Large size group cultivars 'Compacta' and 'Monum' produced fruit with viable seed in quantities comparable to the wild type selection and could therefore have a greater likelihood of escaping into natural areas, as compared to medium size or dwarf size cultivars that produced few if any fruit. Above average visual quality rankings, good survival, and limited or lacking fruit production of 'Gulf Stream', 'Jaytee', and 'Harbour Dwarf' warrant wider landscape use of these selections in the south FL landscape. In north FL,
where the wildtype heavenly bamboo has escaped and is considered invasive, 'Filamentosa', 'Firepower', and 'Moon Bay' did not fruit but were not as attractive as the other taxa. Other cultivars such as 'Gulf Stream' and 'Harbor Dwarf' (that had excellent survival, good winter appearance, and limited fruit production) or 'Jaytee' (that had excellent survival, good summer appearance, and limited fruit production) may be preferred but warrant use of caution in north FL landscapes.
Publications
- Gary W. Knox and Sandra B. Wilson. 2005. Evaluating North and South Florida Landscape Performance and Fruiting of Ten Cultivars of Nandina domestica, a Potentially Invasive Ornamental. Journal of Environmental Horticulture. Submitted.
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Progress 10/01/03 to 09/30/04
Outputs
Plant growth, visual quality, flowering, and fruit production were assessed for 11 heavenly bamboo (Nandina) taxa planted in northern (Quincy) and central-southern (Fort Pierce) Florida. Seed viability and germination tests were preformed from fruit collected from landscape plantings (Nandina domestica 'Harbor Dwarf') and from naturalized areas where it has escaped (Nandina domestica). All cultivars produced fruit in either location with the exception of 'Filamentosa', 'Firepower', and 'Moon Bay', that did not produce any fruit in 2004. In southern Florida, 'Plum Passion' produced the most fruit followed by 'Compacta'. In northern Florida, 'Compacta' yielded the most fruit followed by 'Plum Passion' and the wild type.
Impacts
Invasive species have disrupted thousands of acres of natural areas in Florida alone and appear to have a physiological competitive advantage over native species. The Tampa Bay Wholesale Growers, Florida Nurserymen and Growers Association, and the American Nursery and Landscape Association Board of Directors are the first in the nation to adopt voluntary codes of conduct for the nursery industry with regards to invasive plants. The codes of conduct involve adoption of risk assessment methods that consider plant characteristics and prior observations or experience with the plant elsewhere in the world before it is released and distributed. Research on invasive plants is critical to provide scientific evidence of whether a plant is currently invasive or has great potential to become invasive. This information can then be relayed to the growers, who in turn can make an informed decision on whether or not a particular plant should be produced commercially.
Publications
- Wilson, S.B., M. Thetford, L.K. Mecca, and J.S. Raymer. 2004. Evaluation of 14 butterfly bush taxa grown in western and southern Florida: I. Visual quality, growth and development. HortTechnol. 14:605-612.
- Wilson, S.B., M. Thetford, L.K. Mecca, J.S. Raymer, and J. Gersony. 2004. Evaluation of 14 butterfly bush taxa grown in western and southern Florida: II. Seed production and germination. HortTechnol. 14:612-618.
- Knox, G.W., S.B. Wilson, and L.K. Mecca. 2004. Evaluating eleven Nandina domestica taxa in north and south Florida. Proc. South. Nurs. Assoc. 49:551-555.
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Progress 10/01/02 to 10/01/03
Outputs
Objectives: 1. To determine optimal germination conditions for selected non-native plant species introduced for ornamental use in Florida. 2. To evaluate vegetative and reproductive growth parameters for selected non-native, potentially invasive, species such as seed production, seed viability, leaf area, canopy closure, plant growth and size, root/shoot masses and ratios, biomass allocation, and root areas of potentially invasive plants. 3. To determine if invasive exotics capture limiting resources more efficiently than native or noninvasive species as indicated by nutrient use efficiency, carbohydrate status, and photosynthesis. 4. To evaluate all cultivars of several wildtype species that are invasive Approach: The influence of light and temperature on germination was determined for the invasive Mexican petunia (Ruellia tweediana Griseb.) and native wild petunia (Ruellia caroliniensis Steud.). Seeds were collected and germinated in incubators with light or
darkness at 15, 24, 33 and 30/20 oC. Studies also were initiated to determine if R. tweediana has a competitive advantage over the native species when grown under wet and dry substrate conditions. Net CO2 assimilation (photosynthesis) was measured on young, fully expanded leaves. Measurements were taken from the 3rd and 4th fully open leaf from the apex of each plant at 0, 2, 4, 6, and 8 weeks using a CIRAS portable infrared gas analyzer. At 0 and 8 weeks, total nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) were analyzed within leaf, stem and root tissues. Non-technical Summary: Light increased germination for each species, except at 15 oC (R. caroliniensis). For R. caroliniensis, highest germination (86-94%) occurred at 33 oC and 30/20 oC. Highest germination of R. tweediana (98-100%) occurred at 30/20 oC. Growth and development measurements after 8 weeks under controlled conditions revealed that R. tweediana grown in wet conditions had the greatest dry
weight increase as compared to other treatments. R. caroliniensis had higher specific leaf area when grown in wet or dry conditions, as compared to R. tweediana. Throughout the experiment, net CO2 assimilation of R. caroliniensis grown under dry or wet conditions was consistently lower than that of R. tweediana. Shoot nitrogen and phosphorus use efficiencies were generally greatest for R. tweediana plants grown in wet conditions. For shoot nutrient content, significant species x moisture interactions occurred for measured phosphorus (P) and calcium (Ca). When grown in wet conditions, R. tweediana had less shoot P and Ca as compared to dry conditions. For root nutrient content, species x moisture interactions were insignificant for each measured nutrient, with the exception of potassium (K). Potassium use efficiency of R. tweediana roots grown in wet conditions was higher than that of R. tweediana grown in dry conditions and R. caroliniensis grown in wet conditions.
Impacts
Invasive species have disrupted thousands of acres of natural areas in Florida alone and appear to have a physiological competitive advantage over native species. The Tampa Bay Wholesale Growers, Florida Nurserymen and Growers Association, and the American Nursery and Landscape Association Board of Directors are the first in the nation to adopt voluntary codes of conduct for the nursery industry with regards to invasive plants. The codes of conduct involve adoption of risk assessment methods that consider plant characteristics and prior observations or experience with the plant elsewhere in the world before it is released and distributed. Research on invasive plants is critical to provide scientific evidence of whether a plant is currently invasive or has great potential to become invasive. This information can then be relayed to the growers, who in turn can make an informed decision on whether or not a particular plant should be produced commercially.
Publications
- Wilson, S.B., P.C. Wilson, and J.A. Albano. 2003. Growth and development of the native Ruellia caroliniensis and invasive Ruellia tweediana. HortScience. In press.
- Wirth, F.F., K.J. Davis, and S.B. Wilson. 2003. Florida nursery sales and economic impacts of 14 potentially invasive ornamental plant species. J. Environ. Hort. In press.
- Moller, D. and S.B. Wilson. 2003. Characterizing potential invasiveness of fourteen Buddleja cultivars in South Florida. J. Undergrad. Ed. 5(2)1-12.
- Wilson, S.B. and L.A. Mecca. 2003. Seed production and germination of eight cultivars and the wild type of Ruellia tweediana: A potentially invasive ornamental. J. Environ. Hort. 21:137-143.
- Wilson, S.B. 2003. Characterizing invasive ornamental species of Florida. Proc. Inter. Plant Prop. Soc. In press. Mecca, L.K., S.B. Wilson, M. Thetford, J.S. Raymer, and E.L. Barnett. 2003. Assessing visual quality, growth and seed production of 14 Buddleja cultivars grown in west and south Florida. Proc. South. Nursery Assoc. In press.
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Progress 10/01/01 to 10/01/02
Outputs
The influence of light and temperature on germination was determined for 7 cultivars of Mexican petunia (Ruellia tweediana Leonard ex Fernald). Seeds were collected and germinated in incubators in light (12 hour photoperiod) or darkness at 15, 24, and 30/20 oC. In addition to incubator treatments, parallel greenhouse studies were conducted where seeds were placed on the soil surface or 1 cm below the soil surface. Seed production of each cultivar was recorded monthly and related to germination rates. Invasive species have biological characteristics in common that predispose them towards invasiveness. The wildtype Ruellia tweediana has several invasive qualities, including (1) tolerance of variable conditions including light, temperature, and moisture, (2) aggressive growth, (3) preference to disturbed sites, (4) ability to produce abundant seed over a long reproductive period, and (5) no special seed germination requirements. However, it is not appropriate to deem an
economically important species with high ornamental value as invasive without considering all cultivars. Results of this study show that all Mexican petunia cultivars produced seed, with the exception of Purple Showers. The seed produced by cultivars was far less than the seed produced by wildtype plants but germination rates were similarly high (94-100%) under greenhouse conditions. In addition, seed collected from open-pollinated dwarf cultivars produced 9-16% of wildtype (tall, purple) seedlings.
Impacts
Invasive species have disrupted thousands of acres of natural areas in Florida alone and appear to have a physiological competitive advantage over native species. The Tampa Bay Wholesale Growers, Florida Nurserymen and Growers Association, and the American Nursery and Landscape Association Board of Directors are the first in the nation to adopt voluntary codes of conduct for the nursery industry with regards to invasive plants. The codes of conduct involve adoption of risk assessment methods that consider plant characteristics and prior observations or experience with the plant elsewhere in the world before it is released and distributed. Research on invasive plants is critical to provide scientific evidence of whether a plant is currently invasive or has great potential to become invasive. This information can then be relayed to the growers, who in turn can make an informed decision on whether or not a particular plant should be produced commercially.
Publications
- Krumfolz, L.A. and S.B. Wilson. 2002. Varying Growth and Sexual Reproduction Across Cultivars of Ruellia brittoniana. Proc. Southern Nursery Assoc. In press.
- Krumfolz, L.A., D. Moller, and S.B. Wilson. 2002. Evaluation of Ruellia brittoniana (tweediana) cultivars for potential invasiveness. Proc. FLEPPC (abstract).
- Wirth, F.F., K.J. Davis, and S.B. Wilson. 2002. Nursery Sales and Economic Impacts of 14 Category I Ornamental Plant Species. Proc. FLEPPC (abstract).
- K.J. Davis, F.F. Wirth and S.B. Wilson. 2002. Florida Nursery Sales of 14 Potentially Invasive Ornamental Species. Proc. Southern Nursery Assoc. In press.
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Progress 10/01/00 to 10/01/01
Outputs
Seeds have been collected from 75% of specified plants and germination experiments have been conducted. A second location of plant material has been determined for 50% of plants and germination experiments have been conducted. A comprehensive cultivar evaluation study has been performed on Ruellia brittoniana. A complete photosysnthesis and nutrient use efficiency study has been performed comparing the native and exotic Ruellia. Two manuscripts, two posters, four talks, and three abstracts have been prepared presenting the data. External and internal funding has been secured to fund ongoing research.
Impacts
Present research includes determining the effects of temperature and light on seed germination of potentially invasive ornamental species. Plants are further characterized by measuring vegetative and reproductive potential. Based on findings from these investigations, research will also determine if successful invading species capture limiting resources more efficiently than native species. While seed germination and viability are important predictors of potential invasiveness, it is equally necessary to determine growth and carbon balance (photosynthesis, respiration, and biomass allocation) as well as nutrient-use efficiency of potential invasive species. It is suspected that species with few restrictions on environmental conditions for germination (i.e., temperature, light, moisture, nutrition) and photosynthesis may be potentially invasive, and should then be subjects for screening protocols. Research from the proposed investigation will provide pertinent data
necessary for determining if screening protocols can be accurately developed for plant importers to follow prior to introducing new plants into Florida. The data obtained from the twenty species identified in this study will1 be instrumental towards these efforts and clear candidates to run through the developed screening protocols.
Publications
- Wilson, S.B. and P.C. Wilson. 2001. Could we be producing, purchasing, or planting invasive exotic plants of the future. Proc. FLEPPC (abstract).
- Wilson, S.B., P.C. Wilson, and M.E. Tignor. 2001. Germination of potentially invasive ornamental plants under varying conditions. Hort Sci. 36:556 (abstract).
- Wilson, S.B. and P.C. Wilson. 2001. Characterizing the potential invasiveness of ornamental plants in the Florida landscape. SNA Proc.
- Wilson, S.B., P.C. Wilson, and M.E. Tignor. 2001. Assessment of germination, nutrient uptake and photosynthetic efficiency for evaluating the potential invasiveness of Ruellia brittoniana. Proc. Fla. State Hort. Soc.
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