Herbaceous Ornamentals Research Articles

LANDSCAPE PLANT OBSERVATIONS FROM THE LSU AGCENTER, 2004

Performance evaluations of numerous annual and perennial herbaceous ornamentals were conducted in landscape settings in 2004 at the LSU AgCenter in Baton Rouge. A mid-summer through fall evaluation of Kong coleus found no difference in flowering performance and visual quality ratings of the five available cultivars. In a sun/shade study, Kong coleus cultivars in 60% shade were about 50% shorter than those in sun. Other impressive coleus have been Aurora Black Cherry and Mississippi Summer Sun. The Stained Glassworks series of coleus have been average performers. The Son series of lantanas (Sonrise, Sonset, Samson, Sonshine) have been top performers in terms of visual quality and continual bloom. All-America daylilies most prevalent to rust symptoms have included Judith, Leebea Orange Crush, Starstruck, Lady Lucille, and Chorus Line. Some rust has also been noted on Plum Perfect and Frankly Scarlet. Profusion Apricot and Profusion White have been less susceptible to Xanthomonas bacterial petal blight than Profusion Fire, Profusion Cherry, and Profusion Orange. Earth Kind roses, being promoted by Texas A&M, are being evaluated for landscape performance along with black spot and powdery mildew susceptibility. Most problematic cultivars thus far have included Georgetown Tea, Clotilde Soupert, Nacogdoches, Reve d'Or, New Dawn, Souvenir de St. Anne's, Spice, Lamarque, Puerto Rico, Sarah Jones, Ducher, and Louis Philippe. Lady Bird cosmos have been good late summer/early fall landscape performers.

Prolonged High Temperature Exposure and Daily Light Integral Impact Growth and Flowering of Five Herbaceous Ornamental Species

Flowering of many herbaceous ornamentals is reduced or eliminated under high temperatures. On warm, sunny days, greenhouse growers often cover crops with light-reducing screening materials to reduce air and plant temperature. However, low irradiance can also reduce flowering on many species. To examine the impacts of temperature and irradiance on herbaceous ornamental flowering and to select a model to study high temperature-reduced flowering, Antirrhinum majus L. (snapdragon) `Rocket Rose', Calendula officinalis L. (calendula) `Calypso Orange', Impatiens wallerana Hook.f. (impatiens) `Super Elfin White', Mimulus ×hybridus Hort. ex Siebert & Voss (mimulus) `Mystic Yellow', and Torenia fournieri Linden ex E. Fourn (torenia) `Clown Burgundy' were grown at constant 32 ± 1 °C or 20 ± 1.5 °C under a 16-hour photoperiod with daily light integrals (DLI) of 10.5, 17.5, or 21.8 mol·m-2·d-1. Flower bud number per plant (all flower buds ≥1 mm in length when the first flower opened) of all species was lower at 32 than 20 °C. Reduction in flower bud number per plant at 32 compared to 20 °C varied from 30% (impatiens) to 95% (torenia) under a DLI of 10.5 mol·m-2·d-1. Flower diameter of all species except snapdragon was less at 32 than 20 °C. Decreasing DLI from 21.8 to 10.5 mol·m-2·d-1 decreased flower diameter of all species except snapdragon. Calendula, impatiens, and torenia leaf number below the first flower was greater at 32 than 20 °C, regardless of DLI. Increasing DLI from 10.5 to 17.5 mol·m-2·d-1 increased shoot dry mass gain rate of all species, regardless of temperature. Further increasing DLI from 17.5 to 21.8 mol·m-2·d-1 at 20 °C increased shoot dry mass gain rate of all species except snapdragon and mimulus, indicating that these species may be light saturated below 21.8 mol·m-2·d-1. Under DLIs of 17.5 and 21.8 mol·m-2·d-1 shoot dry mass gain rate was lower at 32 than 20 °C for all species except torenia. Torenia shoot dry mass gain rate was 129 mg·d-1 at 20 °C compared to 252 mg·d-1 at 32 °C under a DLI of 17.5 mol·m-2·d-1. We suggest torenia may be a good model to study the basis for inhibition of flowering under high temperatures as flowering, but not dry mass gain, was reduced at 32 °C.

BA Application Frequency and Concentration Effects on Two Indian Hawthorn Cultivars

Abstract Benzyladenine (BA) is a synthetic cytokinin that promotes lateral shoot development in herbaceous and woody ornamentals and may be a viable alternative to mechanical pruning in nursery production. A study was conducted to determine the effects of BA application number, interval and concentration on two Indian hawthorn [Rhaphiolepis Lindl. Cor. Poir. indica (L.) Lindl. (Crataegus indica L.)] cultivars. In spring 2002, actively growing ‘Olivia’ and ‘Eleanor Taber’ received three applications of 2500 or 5000 ppm BA at a one-, two-, or three-week interval. Data collected four weeks after initial treatment (WAT) reflected the effects of one, two, or three BA applications at each concentration. At this time new shoot counts in both cultivars and foliar injury in ‘Olivia’, but not in ‘Eleanor Taber’, increased with increasing number of applications and BA concentration. Data collected 12 WAT reflected the effects of BA application interval and concentration. At this time new shoot counts increased with decreasing application interval in ‘Olivia’, while ‘Eleanor Taber’ formed the most new shoots when BA was applied at a two-week interval. All treated plants sustained minimal to moderate injury to immature foliage. The experiment was repeated in 2003 using 1750 ppm and 3500 ppm BA on ‘Olivia’ Indian hawthorn. Applications were halted at the first sign of foliar injury resulting in plants treated at one, two, and three-week intervals receiving three, two, and two applications, respectively. New shoot counts on ‘Olivia’ treated at the three application intervals were similar, but greater than those on untreated plants. Control plants had a foliar injury rating similar to that of plants treated at a two or three-week interval, but less than that of plants treated at a one-week interval. Growth index was not affected by treatment in either year.

The impact of photoperiod and irradiance on flowering of several herbaceous ornamentals

Forty-one herbaceous species were grown under short-days (8 h photoperiod, ambient irradiance averaged 12–13.2 and 6.4–8.3 mol m −2 day −1 for Experiments I and II, respectively) with or without supplemental high-pressure sodium lighting (+50, 100, or 150 μmol m −2 s −1); or under long-days delivered using natural day lengths and irradiance with night interruption lighting (2200–0200 h at 2 μmol m −2 s −1 from incandescent lamps) or under ambient daylight plus supplemental irradiance during the day and as a day extension to 18 h (0800–0200 h) with supplemental high pressure sodium lighting (+50, 100, or 150 μmol m −2 s −1) to identify the impact of photoperiod and irradiance on flowering of each species. Days to first open flower, leaf number below first flower, and mean dry weight gain per day (MDWG) were measured when the first flower opened. Twenty-seven species were photoperiodic with examples of five photoperiodic response groups represented: obligate short-day (2), facultative short-day (5), obligate long-day (16), facultative long-day (4); 13 were day neutral (no photoperiod response in flowering). One species, Salvia sclarea L., did not flower. A facultative irradiance response was observed with 10 species; 28 species were irradiance indifferent; 2 had delayed flowering as irradiance increased. Photoperiod affected MDWG of 30 species. Increasing irradiance affected MDWG with 14 species. Photoperiod interacted with irradiance to affect MDWG of 11 species. Cobaea scandens had the greatest MDWG (0.40 g day −1) while Amaranthus hybridus had the least MDWG (0.01 g day −1) across photoperiod and irradiance levels.

Seed Production of Field- and Greenhouse-Grown Herbaceous Ornamental Plants: Flowering and Pollinator Effects

Seeds of herbaceous ornamental accessions conserved by the USDA National Plant Germplasm System (NPGS) are traditionally produced in summer field cages with honey bees (Apis mellifera) when pollinators are required. Efficient methods to produce high-quality seed in greenhouses may allow for year-round seed production. Flower quantities and effects of pollinators on number and weight of seed produced were studied in field cages and greenhouses at the Ornamental Plant Germplasm Center in 2003 in a randomized complete-block experiment. Honey bees, bumblebees (Bombus impatiens), or blue bottle flies (Diptera calliphoridae) were used as pollinators. Field cages and greenhouse compartments with no pollinator were controls. Cultivars used were Antirrhinum majus `Gum Drop', Coreopsis tinctoria `Plains Bicolor', Dianthus chinensis `Carnation' (NPGS accession NSL 15527), Rudbeckia hirta `Indian Summer', and Tagetes patula `Jaguar'. Seeds were harvested, cleaned, weighed, and 100-seed weights calculated. On average Antirrhinum, Dianthus, Rudbeckia and Tagetes produced more flowers in greenhouses, Coreopsis produced more flowers in the field. Coreopsis and Rudbeckia produced more seed per flower on average with field pollination by honey bees, Antirrhinum and Dianthus produced most with bumblebees in the field, and Tagetes produced most with blue bottle flies in the greenhouse. Each genus had similar 100-seed weights on average in all treatments. Results show pollinators other than honey bees are useful for herbaceous ornamental seed production and that seed production in greenhouses may be an alternative method for seed production of herbaceous ornamentals.

Heat Stress Responses of Four Herbaceous Ornamentals Differing in Heat Tolerance

The demand for new and/or improved herbaceous annuals and perennials continues to increase, making information on production and viability of these plants a necessity. In Louisiana and the Southern U.S., one of the greatest impediments to production of marketable herbaceous plants and their longevity is high temperature. Herbaceous plants have various stages of vegetative growth and flowering; high temperatures during these developmental stages can have a tremendous impact on plant metabolism, and thus plant growth and development. The goal of this research was to better understand the differences between heat tolerant (HT) and heat sensitive (HS) species and cultivars at various high temperatures in terms of whole plant growth, flowering, photosynthesis, carbohydrate content, electrolyte leakage, chlorophyll content and plant small heat shock proteins (HSP) expression levels. Salvia splendens Vista Series (HT), Sizzler series (HS); Viola witrokiana `Crystal Bowl Purple' (HT), `Majestic Giant Red Blotch' (HS), F1 Nature Series (HT) and F1 Iona Series (HS); Gaillardia × grandiflora `Goblin' (HT) and Coreopsis grandiflora `Early Sunrise' (HS) were grown from seed in growth chambers under 25/18 °C (day/night) cycles. Plants at 4, 6, and 8 weeks after germination were subjected to different high temperature treatments of 25 (control), 30, 35, 40, and 45 °C for 3 h. Results show that there was a significant difference in net photosynthesis, electrolyte leakage, soluble carbohydrate content and HSP levels between HT and HS cultivars. Effects of high temperature on plant growth, chlorophyll content, and number of days to flower, flower size, and marketable quality were also significantly different.

144 The Ripple Effect: Training Veteran Master Gardeners to Train Incoming Volunteers

Oregon State University Master Gardener volunteers are the backbone of home horticulture program delivery in Oregon. In 1997, more than 800 new Master Gardeners received between 48 and 66 hours of initial training at 17 sites throughout Oregon. A reduction in faculty available to train Master Gardeners and reduced travel budgets for existing faculty have made it difficult to effectively deliver training on a statewide basis. One solution to this problem is to train veteran Master Gardeners to assume some of the teaching duties for the initial training in their respective counties. In Sept. 1998, 45 veteran Master Gardeners attended a 2-day training seminar to learn to deliver two 3-hour training modules to Master Gardener trainees. Participants learned to use curriculum materials developed for training sessions on vegetable gardening and herbaceous ornamentals. Curriculum materials include annotated slide sets, handouts, suggested activities, entry/exit quizzes, and teaching evaluations for each module. Participants also received training on effective teaching strategies for the adult learner. Participants delivered the training in their respective counties during winter 1999 and returned an evaluation of the training experience. Benefits of this program included reduced training expense and teaching time for Extension faculty, increased volunteer commitment and participation in Master Gardener training, an advanced training opportunity for veteran Master Gardeners, availability of curriculum materials for future training, and improved retention of veteran Master Gardeners.

024 IPM Practices Reduce Pesticide Levels in Runoff Water at a Container Nursery

This study investigated effects of two pesticide applications regimes, Integrated Pest Management (IPM), in which pesticides were only applied to affected plants when damage was noticed, and Traditional, in which pesticide applications were made on a scheduled and preventative basis, on growth and health of container grown plants. Field research was conducted at a large wholesale nursery in the piedmont region of South Carolina. An isolated portion of the nursery contained eight beds that housed 25 species of woody and herbaceous ornamentals. IPM beds were subjected to weekly in-depth scouting of indicator species, and all other plant materials in both treatments were visually checked for problems on a weekly basis. The study began in June 1998 with weekly scouting ending in late October. Monthly scouting continued through the winter of 1999. Runoff water was collected from the treatments after all pesticide applications and analyzed to determine concentrations of chemicals. Plant health was rated at study's end to allow comparison between treatments. Amounts of isoxaben detected in runoff water were 7.9 g for the traditional treatment and 0.9 g for the IPM treatment. Amounts of thiophanate-methyl and chlorothalinol were similarly lower for the IPM treatment. Preliminary results indicate that plant growth was similar for both treatments.

Growth of Ornamental Plants in Compacted Soils in Relation to Root Growth under Low Oxygen and High Atmospheric Pressure

In urban situations, particularly after construction, herbaceous ornamentals may be planted into soils that are compacted or have poor structure so that plant roots may encounter poor aeration or physical resistance. Low oxygen concentrations may be the most important aspect of poor aeration and are readily reproduced in the laboratory. High atmospheric pressure might be used to screen for the ability to grow against physical resistance. We tested the suggestion that “native” plants would grow better in compacted soils than typical bedding plants and for differences in tolerance to low oxygen or high pressure. Plants were grown from seed in the greenhouse at four levels of compaction in peat-based medium and in field soil. Shoot dry weights of the native plants Asclepias tuberosa, Echinacea purpurea, and Schizachyrium scoparius, were less affected by growth in compacted soil or peat medium than those of the bedding plants, Antirrhinum majus, Gypsophila elegans, Impatiens balsamina, Tagetes patula and Zinnia elegans. The oxygen content of media declined with compaction to a minimum of 10 kPa. Half maximal root elongation was observed at 1 to 3 kPa oxygen for most species without any separation between the groups. A presure of 1100 kPa reduced root elongation of the bedding plants by 50 to 70% but only 5 to 20% for the native plants.

Demand for Herbaceous Ornamental Germplasm from the North Central Regional Plant Introduction Station

In 1991, the USDA–ARS North Central Regional Plant Introduction Station made available for distribution 129 accessions of germplasm representing 31 genera of herbaceous ornamentals. This number increased to 329 accessions of 42 genera by 1995. During 1991–95, more than 500 seed packets were distributed to fulfill requests for these plants received from a diverse array of public and private researchers. An analysis of this demand together with expert advice from Crop Germplasm Committees and technical considerations, such as ease of culture and seed production, can help set priorities to plan germplasm regeneration to meet future demand. A recent analysis of demand at U.S. National Plant Germplasm System active sites indicated that demand ranging between 0.23 and 0.97 distributions per available accession per year was typical. Of the 42 ornamental genera analyzed in this study, 9 were demanded more frequently than was typical, 10 were demanded less frequently, with the remainder in the typical range. In order of increasing frequency, the nine genera with the highest distribution rates were Verbena, Gypsophila, Echinacea, Lapeirousia, Delphinium, Cerastium, Baptisia, Lilium, and Tanacetum. Six of these genera are represented only by a single available accession. Notably, Echinacea and Tanacetum are of research interest both as ornamentals and as medicinal/industrial crops. This poster gives a brief overview of the economic value of these genera, display the results of the demand analysis, discuss the results relative to recommendations from Crop Germplasm Committees and requestors, and consider how demand can shape management plans for the acquisition and regeneration of ornamental germplasm.

Plant Introductions from the Mt. Cuba Center

Over the past 7 years, eight plants have been introduced from the Mt. Cuba Center for the Study of Piedmont Flora—two woody and six herbaceous ornamentals—which will be illustrated and described. Cornus sericea `Silver and Gold', 1988, is a sport of and similar to `Flaviramea' with white variegated leaves. Aster novae-angliae `Purple Dome', 1989, is a widely known and compact form (50 cm tall) of the species. Heuchera americana `Garnet', 1989, has shiny green foliage of the species mottled garnet-red. Solidago sphacelata `Golden Fleece', 1989, is a compact (50 cm) form of the species with semi-evergreen basal foliage, winning the ISU outstanding plant award in Switzerland in 1994. Leucothoe axillaris `Greensprite', 1991, is easy to propagate and quick to grow, with solid green, narrow leaves with undulating edges and attenuated tips. Pachysandra procumbens `Forest Green', 1992, has larger leaf whorls and a more smoothly undulating surface than the species. Trillium grandiflorum `Quicksilver', 1992, is similar to the species only with 1-year doubling time. Aster laevis `Bluebird', 1995, is similar to the species but has so far been free from foliage diseases.

376 COOPERATIVE LEARNING IN AN HERBACEOUS ORNAMENTAL PLANTS IDENTIFICATION CLASS

Twenty-three students of HORT 2212: Herbaceous Ornamental Plants divided into five teams, each selecting one of the ground beds at the television studio gardens of Oklahoma Gardening to design with the aid of MacDraw II and Macintosh computers. The team approach promoted cooperative learning, where those who were skilled in design worked cooperatively with those individuals more skilled at developing the theme gardens' cultural pamphlets. This project encouraged individual students to develop various communication skills to support their team's thematic garden-visual, in the form of a CAD plot of the garden design; written, in the form of a garden pamphlet; and telecommunication, in the form of Oklahoma Gardening television segments. The students and OBGA Ambassadors started the seeds and, then, planted the gardens, resulting in a very practical experience. This design and installation project not only prepared students for the cooperative efforts that they are likely to encounter in the ornamental horticulture and landscape design and maintenance industries, but also imparted pride in their work, which was viewed by over 150,000 television viewers and visitors weekly.

INVESTIGATION OF NATIVE ORNAMENTAL RESOURCES IN MOUNT HUANGSHAN (EASTERN CHINA)

The author investigated, recorded, observed and analyzed the major wildflowers in Mount Huangshan---the natural and cultural heritages listed by the ESC0 of UN for the first time. On the basis of their desirable characteristics, more than 300 wild ornamental species are divided into 8 categories -–-historical old trees, rare and endangered species, evergreen ornamentals, blooming trees and shrubs, plants with colored foliage and fruit in fall, vines, herbaceous ornamentals and ground covers, and ornamental ferns. Mount Huangshan is one of the richest regions of native ornamentals in Eastern China and the most famous natural beauty in Pan-China. There are about 1500 wild landscape plants in and around it. Finally the paper puts forth some proposals and methods for introduction and utilization of wild ornamental plants. That is, investigation, classification,acclimatization and cultivation of them, and building a sort-out botanical garden for the germplasmic preservation and the flourishing landscape tourism.

Maladera castanea . [Distribution map

Abstract A new distribution map is provided for Maladera castanea (Arr.) (Col., Melolonthidae) (Asiatic Garden Beetle (U.S.A.)) Hosts: Larva a root feeder in turf, etc., adult defoliates trees, shrubs, herbaceous ornamentals and vegetable crops. Information is given on the geographical distribution in ASIA (excl.USSR), China, Japan, Korea, NORTH AMERICA, U.S.A.