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Robert D. Berghage and Royal D. Heins

Elongation characteristics of each internode on a lateral shoot of poinsettia (Euphorbia pulcherrima Klotz) `Annette Hegg Dark Red' were determined from pinching through anthesis for plants grown with 36 day/night temperature (DT/NT) combinations between 16 and 30C. The Richards function was used to describe the elongation of each internode. The first internode developing on a lateral shoot was longer and matured faster than subsequent internodes. The length of the first internode was a function of the difference between day and night temperatures (DIF = DT - NT). Subsequent internodes elongated uniformly in the absence of flower initiation. In the absence of flower initiation, the length of an internode, after the first, was a function of DIF. Internodes were shorter as proximity to the inflorescence increased. Internode length after the start of short days was a function of DIF and the visible bud index where visible bud index = [(days from pinching to the day an internode began to elongate - days from pinching to the day of the start of flower initiation)/the number of days from pinching to visible bud]. A poinsettia lateral shoot elongation model was developed based on the derived functions for internode elongation. The model predicted lateral shoot length within one standard deviation of the mean for plants grown in a separate validation study with 16 combinations of DT/NT. The model allows the prediction of lateral shoot length on any day from pinching through anthesis based on temperature, the number of nodes on the lateral shoot, the time each internode on the lateral shoot began elongating, and the visible bud index at the start of elongation of each node.

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Robert D. Berghage, Alan Michael, and Mike Orzolek

Current and future plans for reductions in federal and state funding suggest that government supported programs must find ways to reduce costs while maintaining or expanding programs. The current model of extension, with an agent for each commodity in every county is not likely to survive. Furthermore, the days when university-based specialists could afford to make house calls also are probably limited. Yet, the need for extension support in the floriculture industry is as great as ever. Increased chemical costs and regulatory pressure are restricting grower options and making it increasingly important that information dissemination and technology transfer occur in timely and appropriate ways. To try to meet the needs of the floriculture industry in Pennsylvania, we have begun a program to help develop independent greenhouse crop management associations to work with milti-county and university-based extension specialists to improve program delivery to the member greenhouses. The first of these associations has been established in the Capital Region in central Pennsylvania and is providing IPM scouting and crop management services to member greenhouses. Development of associations and linkages with and the role of extension are discussed.

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Martin R. McGann and Robert D. Berghage

The Pennsylvania State University Medieval Garden (PSMG) showcases varieties of medieval plants used as ornamentals, food crops, medicinal ingredients, and for household purposes in a stylized setting representing a medieval garden. Since its installation, various colleges within the university as well as community groups have used the garden as an alternative classroom for learning activities, educational demonstrations, and events related to the medieval period. This article focuses on the initial development of the garden design and how the installation and continued use as a classroom has contributed to meeting educational goals for students in the landscape contracting program at the Pennsylvania State University and the Pennsylvania Governor's School for Agricultural Sciences.

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Erin P. MacNeal and Robert D. Berghage

Recirculating irrigation systems (RISs) conserve water and decrease fertilizer application, providing cost-effective alternatives to other watering methods in greenhouses. However, RISs can potentially become contaminated from spray or drench pesticide applications. In this study, we determined the amount of metalaxyl residues (the active ingredient in Subdue) in RISs over 3 and 6 weeks using HPLC analysis. Also examined was the potential use of constructed wetlands for the remediation of RIS water contaminated with metalaxyl. Metalaxyl was found to persist in a RIS over 6 weeks with no decrease in concentration. After repeated metalaxyl treatments over an 11 month period, a possible breakdown product or chemical modification of metalaxyl was present in the RISs. Drench applications, 150 ml of an 18.8 ppm metalaxyl solution, (recommended dosage) resulted in 0.5 to 3.0 ppm contamination levels in the RISs. Small scale (≈70 L void volume), indoor, constructed wetlands (two planted with Scirpus and Iris, two unvegetated) were treated with 420 mg metalaxyl. Limited breakdown of metalaxyl occurred in the constructed wetlands during the first 30 days after treatment. After 3 months, metalaxyl concentrations in all wetlands had decreased or were below detection levels. This indicates a possible selection of microbial populations capable of metabolizing or degrading metalaxyl.

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Christine E. Thuring, Robert D. Berghage, and David J. Beattie

Plants suitable for extensive green roofs must tolerate extreme rooftop conditions, and the substrates in which they grow must fulfill horticultural and structural requirements. Deeper substrates may retain more water for plants during dry periods, but will also weigh more, especially when near saturation. A study in central Pennsylvania was conducted to evaluate the influence of substrate type and depth on establishment of five green roof plants. Two stonecrops [white stonecrop (Sedum album) and tasteless stonecrop (Sedum sexangulare)], one ice plant (Delosperma nubigenum), and two herbaceous perennials [maiden pink (Dianthus deltoides) and saxifrage pink (Petrorhagia saxifraga)] were planted in three depths (30, 60, and 120 mm) of two commercially available green roof substrates (expanded shale and expanded clay). Study flats inside a plasticulture tunnel received three drought treatments (no drought, 2 weeks early drought, and 2 weeks late drought). The two stonecrops performed well under most conditions, although tasteless stonecrop was stunted by early drought. Ice plant only grew well when provided with water. When subjected to any drought, the herbaceous perennials had the fewest survivors in the expanded shale. Saxifrage pink flowered profusely wherever it survived. The study plants were most affected by substrate depth, except for maiden pink, which responded solely to drought. When subjected to early drought conditions, the herbaceous perennials did not survive in 30 mm of either substrate, or in 60 mm of expanded shale. Although the stonecrops performed well in 60 mm of substrate when subjected to drought, their performance was superior in the expanded clay compared with shale.

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Kathryn L. McDavid, David L. Sanford, and Robert D. Berghage

Green roof construction is constrained by cost of labor to install the plant material. Optimizing seed germination and establishment could significantly reduce installation costs but would require specific growing conditions that are difficult to provide during installation. Plants of the stonecrop (Sedum) genus are commonly used for the roof top because they will tolerate the high temperatures. This study compared the germination rates of four stonecrop species {goldmoss sedum (Sedum acre), ‘Oracle’ sedum (Sedum forsterianum), blue spruce sedum (Sedum reflexum), and amur sedum [Sedum selskianum (synonm Phedimus selskianum)]} at two temperatures, 70 and 90 °F, following storage of seed in dry, cool (40 °F) conditions of different durations (54, 98, 157, 197, 255, or 343 days). At 70 °F seed of goldmoss sedum, ‘Oracle’ sedum, and blue spruce sedum produced minimum germination rates of 60% at 21 days in seed stored for 54, 98, 157, 197, 255, or 343 days. Goldmoss sedum, ‘Oracle’ sedum, and blue spruce sedum showed reduced germination in 90 °F, probably due to temperature-induced dormancy. Amur sedum had germination of at least 83% at 21 days in both temperatures tested. As amur sedum germination rates appear to be unaffected in the temperatures tested, it could provide an excellent seed for use on green roofs where ideal temperatures are rarely available.

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Michael D. Orzolek, Cathy Thomas, Robert D. Berghage, and Paul R. Heller

The dramatic reduction in available greenhouse insecticides and the potential for increased insect resistance has necessitated a change in insect control techniques. Because of the large acreage of greenhouse production in Pennsylvania and the need for a more environmentally effective method of controlling insects in greenhouses, an aggressive Integrated Pest Management research program was initiated and has been on-going since 1989. Our objectives were to develop a bibliography of major insect pests; to determine effectiveness of parasitoids on greenhouse and silverleaf whitefly, western flower thrip, and aphids; to reduce pesticide usage; and to comply with worker protection standards. The program was implemented by a joint venture among the Pennsylvania State Univ. faculty and technical staff, grower cooperators, the Pennsylvania Dept. of Agriculture, and the Pennsylvania Vegetable Growers Association. The IPM program was started with an active scouting and monitoring program in commercial houses to determine threshold levels. Control measures were implemented with biological controls, cultural management, and lastly chemical. In addition, the implementation of the results of this research to commercial growers has resulted in the formation of a Greenhouse Crop Management Association. Results of the 5-year research program are discussed.

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Rebecca H. Wehry*, Kathleen M. Kelley, Robert D. Berghage, and James C. Sellmer

Gardeners can provide the best insight to their gardening experiences and interests. In order to identify potential buyers of the state plant promotional program, Pennsylvania Gardener Selects (PGS), an intercept survey with 243 participants was conducted at the Philadelphia Flower Show on 6-7 Mar. 2003. Objectives were to better understand Pennsylvania consumer's: current gardening related shopping habits; where they obtain gardening information; and their motives and limitations for pursing gardening. Responses were analyzed to identify potential consumer segments who might purchase PGS plants. Participants with an income >$50,000 (55%) are more likely to gather their gardening information from a university website than those with an income <$50,000 (39%). Respondents with a college education (59%) reported that time was the limiting factor when gardening as compared to those with only a high school diploma (44%). Survey responses were also analyzed using Cluster Analysis, which generated three distinct consumer segments: “Novice Gardener” (consumers with limited experience in gardening), “Non-Gardener” (consumers who prefer not to garden), and “Avid Gardener” (consumers who spend the majority of their leisure time gardening). “Avid Gardeners” are likely to purchase plants evaluated for Pennsylvania (average response of 6.5; scale 1 to 7) and 73% have purchased Pennsylvania products. They also are more likely to purchase their landscape plant material at local nurseries/garden centers (82%) than the other segments (68%). Based on the results it can be assumed that “Avid Gardener” could be a potential market for PGS plants. A marketing strategy for reaching this audience may consist of promotions at local nurseries/garden centers along side other Pennsylvania-grown products.

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Robert D. Berghage, Dennis J. Wolnick, E. Jay Holcomb, and John E. Erwin

The Internet offers many new and unique opportunities to disseminate information. The development of the World Wide Web (WWW) and information browsers like Netscap, Mosaic, and simple-to-use server software like MacHTTP provides means to allow low-cost access to information, including pictures and graphics previously unavailable to most people. The Pennsylvania State Univ. variety trial garden annually tests >1000 plants. Information is gathered on garden and pack performance, and photos of superior plants and varieties are taken. To provide wider access to this information, we have begun development of a Cyberspace trial garden on the internet. This server contains a wide variety of garden trial information developed from trials conducted in State College and Dauphin, Pa.. This server and a similar effort at Univ. of Minnesota are being constructed cooperatively. Hot links are provided between the server in Pennsylvania and the one in Minnesota, providing users with seamless access to information from both servers.

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Rebecca H. Wehry, Kathleen M. Kelley, Robert D. Berghage, and James C. Sellmer

A consumer-research study was conducted in two locations in Pennsylvania utilizing two survey methods: intercept and telephone. This study was designed to assess: 1) what national brand name plant material participants purchased in the past; 2) the consumer's awareness of the Pennsylvania Gardener Selects (PGS) program; and 3) the gardening habits and demographics of Pennsylvania gardeners. The first survey was an intercept survey of 390 self-selected participants who attended Ag Progress Days (APD), a 3-day outdoor educational event and farm implement show from 20-22 Aug. 2002. The second survey was a telephone survey of 500 randomly selected households in the metro-Philadelphia area and was conducted from 20 Aug. through 17 Sept. 2002. Only responses from Pennsylvania gardeners were used in the analysis of the results. A comparison of survey results indicated that metro-Philadelphia-area participants spent more on plant material annually than APD participants, who primarily resided in rural locations. The results showed that metro-Philadelphia-area gardeners tend to live in single-adult households and have one or more children, whereas APD gardeners tend to live in a household with two or more adults and have no children. Eighty-one percent of APD participants and 62% of metro-Philadelphia participants reported that they would be willing to purchase plant material that has been evaluated and chosen as being outstanding for use in all areas of Pennsylvania, a premise for the PGS program.