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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.

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.

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.

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.

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.

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.

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.

Abstract

Lateral shoot growth and plant morphology of poinsettia (Euphorbia pulcherrima Willd.) were influenced by the pinching technique used for apical meristem removal. Plants were pinched in one of four ways: 1) soft (removal of the apical meristem plus stem and leaf tissue associated with leaves ≤2 cm long); 2) medium (removal of the apical meristem plus stem and leaf tissue associated with leaves up to 7 cm long); 3) hard (removal of the apical meristem plus stem and leaf tissue associated with all immature leaves); and 4) leaf removal (LR; soft pinch as defined above plus removal of all immature leaves but not the associated stem tissue). Initial growth of lateral shoots on soft and some medium-pinched plants was less than initial growth of lateral shoots on hard- or LR-pinched plants. Shorter lateral shoots and longer primary stems at anthesis on soft-pinched plants resulted in vertical plant architecture. Hard- and LR-pinched plants had a more horizontal plant architecture. The average height : width ratio of soft-, hard-, and LR-pinched plants at anthesis was 0.77, 0.68, and 0.63, respectively. Of 10 commercial cultivars tested in 1987, 48% of the inflorescences of soft-pinched plants developed below the bract canopy, compared with 27% and 31% for hard- and LR-pinched plants, respectively. These results show that the use of a soft pinch to increase inflorescence number in the bract canopy is not productive if immature leaves are left on the plant when pinching.

Two separate studies using intercept survey methodology were conducted to define the components of a state plant promotional program—Pennsylvania Gardener Selects (PGS)—based on consumer preference and appeal. The first study, conducted 6 and 7 Mar. 2003 at the Philadelphia Flower Show in Philadelphia, Pa., involved 243 Pennsylvanians. Objectives were to define current gardening-related shopping habits, sources of gardening information, motives and limitations for pursuing gardening, and history of purchasing other Pennsylvania products. Responses were analyzed using cluster analysis to identify consumer–gardener segments that would potentially purchase PGS plants. Three distinct consumer segments were generated: “Novice Gardeners” (consumers with limited experience in gardening), “Casual Gardeners” (consumers with limited confidence in their gardening knowledge), and “Avid Gardeners” (consumers who express great interest in gardening). “Avid Gardeners” exhibited a greater level of interest in purchasing plants evaluated for Pennsylvania (average response, 6.5; based on a scale of 1 to 7, where 1 is very unlikely and 7 is very likely), with 73% indicating that they had purchased Pennsylvania products; hence, they were a potential market for PGS plants. The second study, conducted 8 to 10 Mar. 2004 at the Philadelphia Flower Show involved 250 Pennsylvanians. Objectives for this study were to define consumer brand and product preferences, including container colors for the PGS program, plant tag style/color, and retail price (based on a scale of 1 to 7, where 1 is very unlikely to purchase and 7 is very likely to purchase), as well as brand attributes these consumers valued. Responses were analyzed using conjoint analysis. Participants awarded the highest utilities to the white container with a black-and-white PGS logo (0.1149), keystone-shaped tag with color image and PGS logo (0.1099), and a retail price of $1.98 (0.4751). Spearman's rho was used to identify relationships among existing and related brand attributes. Correlations between participants’ response to brand attributes, including locally grown, ideal for local conditions, quality assurance, and independent testing program, as well as plant guarantee and publication with gardening tips, suggest that promotional materials should emphasize and include these qualities. Results from these studies indicate that there is interest in a state plant promotional program for Pennsylvania. To use resources wisely, consumers classified as “Avid Gardeners” would be the most appropriate to target first. To attract consumer attention and encourage purchasing at a retail outlet, containers and plant tags should have distinctive colors, and brand attributes and resulting consumer benefits should be emphasized on promotional materials.

A set of studies was established in Summer 1998 to determine the tolerance of field-grown cut flower species to specific preemergence herbicides, the effectiveness of weed control by those materials, and to determine if productivity of cut flowers is affected either by the herbicides or by colored mulches. Pendimethalin provided excellent early season weed control, but poor late-season control. It consistently caused injury at 4 lb a.i./A and sometimes at the 2 lb a.i./A rate. Oryzalin provided good to excellent weed control, but slightly injured celosia and zinnia when applied at 4 lb a.i./A. Napropamide provided excellent early season weed control, but marginally acceptable weed control later in the season. Though napropamide caused some injury to celosia early in the season when applied at the high rate, no injury to any of the plants was observed later in the season. Prodiamine and trifluralin were the overall safest of the herbicides, but they provided the weakest weed control. OH-2 was very effective when placed on the soil surface, but was less effective when placed on an organic mulch. The organic mulch was designed to keep the OH-2 particles from splashing on to the crop plant and injuring the plants. OH-2 tended to be safer placed on a mulch than on the soil surface, but statice was slightly injured even when a mulch was used.