bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimum Nitrogen Fertilization for Production of Containerized Raphiolepis × delacourii ‘Snow White’
Authors: Tillman Amy L. , Warren Stuart L. , Blazich Frank A. 
Published: August 2020

Abstract
Rooted stem cuttings of ‘Snow White’ raphiolepis (Raphiolepis × delacourii Andre ‘Snow White’) were grown in 3.8-liter (#1) black plastic containers containing a pine bark:sand (8:1, by vol) substrate. Plants were fertilized at every irrigation, for 17 weeks, with a 4:1:2 nitrogen (N):phosphorus (P):potassium (K) nutrient solution containing N at 20, 60, 100, 140, 180, 220, or 240 mg·L−1 (ppm) supplied as ammonium nitrate (NH4NO3). Maximum top and root dry weights were achieved with N at 145 mg·L−1. Substrate solution electrical conductivity increased linearly with increasing nitrogen application rate (NAR) with maximum growth occurring at 1.28 dS·m−1, whereas substrate solution pH decreased linearly with increasing NAR with a pH of 5.3 at 145 mg·L−1. Increasing the N rate beyond 145 mg·L−1 had minimal effect on top or root dry weight. Leaf area peaked at a NAR of 171 mg·L−1 with a plateau at 524 cm2. Leaf area increased 275% as the NAR increased from 20 to 171 mg·L−1. Specific leaf area increased linearly with increasing NARs. Carbon allocation between tops and roots was unaffected by NARs from 60 to 280 mg·L−1. Root:top ratio decreased 56% between the pooled NARs (60 to 240 mg·L−1) and N at 20 mg·L−1. Leaf area ratio increased linearly with increasing NARs. Foliar mineral nutrient concentrations of N, P, and sulfur increased linearly with increasing NAR, whereas concentrations of K, calcium, magnesium, and copper responded quadratically to increasing NARs. Top growth increased from inadequate at a NAR of 60 mg·L−1 to optimum at 145 mg·L−1, whereas root growth was relatively similar over the same range. At 145 mg·L−1, mineral nutrient concentrations of the top are well within or exceed accepted levels reported, and growers can expect rapid growth of rooted cuttings.
Evaluation of a Sib-mated Population of Buddleja davidii ‘White Bouquet’ × Buddleja indica Hybrids
Authors: Dunn Bruce L. , Lindstrom Jon T. 
Published: August 2020

Abstract
A hybridization experiment to sib-cross a population of B. davidii Franch. ‘White Bouquet’ × B. indica Lam. hybrids was initiated in 2004 to generate a larger population of such hybrids to assess landscape potential. Large populations from the sib-mated B. davidii ‘White Bouquet’ × B. indica hybrids can be generated. The population was initially assessed for growth habit, leaf size, floriferousness, seed morphology, and winter hardiness. Susceptibility to spider mite damage was also noted in the population. Although these hybrids have desirable traits such as non-dehiscent fruit and ornamental foliage, further hybridization is needed to address undesirable traits such as sparse growth and flowering along with spider mite susceptibility.
Arbuscular Mycorrhizal Inoculation Affects Root Development of Acer and Magnolia Species
Authors: Wiseman P. Eric , Wells Christina E. 
Published: August 2020

Abstract
The effects of arbuscular mycorrhizal fungi (AMF) inoculation on fine root development of four woody landscape plants were studied during the first year after transplant. Test species included two members of obligately mycorrhizal Magnoliaceae (Magnolia virginiana and Magnolia stellata) and two members of facultatively mycorrhizal Aceraceae (Acer × freemanii and Acer buergerianum). Field-grown, balled and burlapped plants were treated with a commercial inoculant containing Glomus spp. and Gigaspora spp. mycorrhizal fungi and transplanted to a piedmont field site. Root architecture and demographics were evaluated in situ using minirhizotrons. One year after transplant, AMF colonization levels had increased in three of the four species regardless of whether they had been intentionally inoculated. AMF-treated M. virginiana and A. buergerianum had significantly lower standing root crops (total root length visible on minirhizotrons) than control plants, and a similar trend was observed in Acer × freemanii. Inoculated M. virginiana roots exhibited reduced branching and shorter life spans, but were less likely to develop brown pigmentation. Species-specific effects of inoculation on root longevity and browning were also observed in the maples. AMF inoculation had no effect on above ground growth or foliar nutrient concentrations. Investment of photosynthate in the growth and maintenance of AMF may represent a more efficient nutrient acquisition strategy than root proliferation, leading to lower fine root production in heavily mycorrhizal plants.
Application Interval and Concentration Affect Nursery Crop Response to Cyclanilide
Authors: Williamson Z. , Keever G.J. , Kessler J.R. , Olive J.W. 
Published: August 2020

Abstract
Cyclanilide (CYC) is a bioregulator that promotes the development of lateral shoots in ornamental and fruit tree crops, potentially reducing the need for mechanical pruning during nursery production. In 2006, three foliar applications of 200 ppm CYC applied at a 1, 2, or 3 week application interval increased shoot counts of ‘Diana’ sasanqua camellia, ‘Sky Pencil’ holly, and ‘Snow White’ Indian hawthorn when compared to pruned and unpruned controls. However, application interval had no effect on shoots counts in holly or camellia and minimal effect in Indian hawthorn. Foliar injury to Indian hawthorn was severe, regardless of application interval. In 2007, three applications of 50 or 100 ppm CYC were applied at a 1, 3, or 6 week interval to ‘Sky Pencil’ holly and ‘Snow White’ Indian hawthorn. At 120 to 150 days after initial treatment (DAIT), shoot counts in both species increased with application interval, and all CYC-treated plants formed more new shoots than controls. Transitory injury to new growth of Indian hawthorn, although not quantified, appeared to increase as application interval decreased. At 120 DAIT foliar injury was no longer evident in Indian hawthorn. At 180 DAIT quality rating of both cultivars increased with CYC application interval and was greater than that of controls, and CYC-treated plants were visibly more dense and compact.
Nitrogen Nutrition of Eastern Redbud (Cercis canadensis)
Authors: Wooldridge John M. , Warren Stuart L. , Blazich Frank A. 
Published: August 2020

Abstract
Containerized seedlings of eastern redbud were grown in a greenhouse for 10 weeks with nitrogen application rates (NARs) ranging from 0 to 300 mg·L−1. Seedlings fertilized with nitrogen (N) at 180 mg·L−1 had the greatest leaf area, leaf dry weight, and total plant dry weight. Plants allocated more resources to root growth at NARs &lt; 60 mg·L−1. At NARs ≥ 60 mg·L−1, allocation of carbon to roots and tops was constant, with a root:top ratio of 0.25. Foliar concentrations of N, phosphorus, and sulfur increased linearly with increasing NAR while concentrations of potassium were not affected by NAR. Foliar concentrations of calcium and magnesium responded quadratically with minimum concentrations at 240 and 180 mg·L−1, respectively. Boron also responded quadratically with maximum concentrations predicted at a NAR of 175 mg·L−1. Concentrations of copper decreased linearly with increasing NAR. Foliar iron, manganese (Mn), and sodium were not significantly affected by NAR. Foliar Mn concentrations were generally low and approached critical levels. Based on observed growth and the concentrations of various mineral nutrients, we conclude that during the first season of growth containerized eastern redbud should be fertilized with N at 180 mg·L−1 per daily irrigation.
A Test of Four Models to Predict the Risk of Naturalization of Non-native Woody Plants in the Chicago Region
Authors: Widrlechner Mark P. , Thompson Janette R. , Kapler Emily J. , Kordecki Kristen , Dixon Philip M. , Gates Galen 
Published: August 2020

Abstract
Accurate methods to predict the naturalization of non-native woody plants are key components of risk-management programs being considered by nursery and landscape professionals. The objective of this study was to evaluate four decision-tree models to predict naturalization (first tested in Iowa) on two new sets of data for non-native woody plants cultivated in the Chicago region. We identified life-history traits and native ranges for 193 species (52 known to naturalize and 141 not known to naturalize) in two study areas within the Chicago region. We used these datasets to test four models (one continental-scale and three regional-scale) as a form of external validation. Application of the continental-scale model resulted in classification rates of 72–76%, horticulturally limiting (false positive) error rates of 20–24%, and biologically significant (false negative) error rates of 5–6%. Two regional modifications to the continental model gave increased classification rates (85–93%) and generally lower horticulturally limiting error rates (16–22%), but similar biologically significant error rates (5–8%). A simpler method, the CART model developed from the Iowa data, resulted in lower classification rates (70–72%) and higher biologically significant error rates (8–10%), but, to its credit, it also had much lower horticulturally limiting error rates (5–10%). A combination of models to capture both high classification rates and low error rates will likely be the most effective until improved protocols based on multiple regional datasets can be developed and validated.
Performance of Florida Landscape Plants When Irrigated by ET-Based Controllers and Time-Based Methods
Authors: Shober Amy L. , Davis Stacia , Dukes Michael D. , Denny Geoffrey C. , Brown Sydney Park , Vyapari Sudeep 
Published: August 2020

Abstract
The combination of inefficient irrigation of residential and commercial landscapes and prolonged drought conditions has overextended the water supply in many areas of Florida. New irrigation technologies including smart irrigation controllers have been shown to decrease outdoor water use. The objective of this study was to evaluate the effects of evapotranspiration (ET) controlled and time-based irrigation treatments on the growth and quality of three ornamental plant species grown in landscape settings in Florida. Plumbago auriculata, Lagerstroemia ‘Natchez’, and Liriope muscari ‘Big Blue’ were established in mixed irrigation plots in a completely randomized block design with four irrigation treatments: 1) Weathermatic ET controller treatment; 2) Toro ET controller treatment 3) time-based treatment (determined by month from 60% of historical net irrigation requirement specific to South Florida) and; 4) reduced time-based treatment (irrigation depth in treatment 3 was reduced by 40%). Results for the entire study period showed that the use of ET controllers did not result in water savings over the reduced time treatment. There was no irrigation treatment effect on plant growth (growth index or height) of Plumbago auriculata, Lagerstroemia indica ‘Natchez’, or Liriope muscari ‘Big Blue’ over the course of the study. Similarly, plant density and quality were unaffected by irrigation treatment throughout the study. These results suggest that all irrigation treatments applied more water than was needed and that these species would perform acceptably with less irrigation than supplied by the lowest treatment in the study.
Cold Hardiness of Weigela (Weigela florida Bunge) Cultivars
Authors: McNamara Steve , Hokanson Stan C. 
Published: August 2020

Abstract
Factual information regarding the low-temperature tolerances of weigela (Weigela florida Bunge) cultivars is essential for identifying cultivars to grow and sell in northern regions of the country [USDA Hardiness Zone 4a;−32 to−34C (−25 to−30F) average annual minimum temperature]. In this study, laboratory freezing tests and a replicated field trial were utilized to compare the relative stem hardiness of 11 recent weigela introductions with that of four standard cultivars representing a known range of hardiness. Freezing tests were conducted monthly from October 2005 to April 2006 on containerized plants over-wintered in a minimally-heated greenhouse under a non-lethal temperature regime conducive to cold acclimation. The cultivars differed substantially in both timing and rates of cold acclimation and de-acclimation in the fall and spring, respectively, as well as maximum midwinter hardiness levels. All of the cultivars, including the cold-hardy standards ‘Minuet’ and ‘Java Red’, were relatively slow to acclimate in early October, but subsequent acclimation rates among cultivars ranged from 0.3 to 0.7C (0.6 to 1.25F) per day between mid-October and mid-November. Maximum midwinter hardiness levels of the new cultivars were within the range defined by the most and least cold tolerant standard cultivars (‘Java Red’ and ‘Variegata’, respectively). With the exception of ‘Java Red’, all cultivars had de-acclimated substantially by March 16, but actual hardiness levels among the new cultivars on this date differed by as much as 10C (18F). Overall, ‘Pink Poppet’, ‘Dark Horse’ and ‘Ruby Queen’ were the hardiest of the new cultivars evaluated with a maximum midwinter hardiness level of−35C (−31F). ‘Alexandra’, ‘Evita’, and ‘Sunny Princess’ exhibited hardiness comparable to that of the moderately hardy standard ‘Red Prince’ and would likely experience moderate to severe injury during colder winters in Zone 4a. ‘Brigela’, ‘Carnaval’, ‘Elvera’, ‘Goldrush’ and ‘Rubidor’ appear to be unsuitable for use in Zone 4a due to late acclimation, insufficient midwinter hardiness, early de-acclimation or a combination of these characteristics. Results of limited testing conducted in 2007–2008 indicate ‘Verweig’, a more recent introduction, is sufficiently cold tolerant for Zone 4a.
Comparison of Water Management in Container-Grown Nursery Crops using Leaching Fraction or Weight-Based On Demand Irrigation Control
Authors: Prehn A.E. , Owen J.S. , Warren S.L. , Bilderback T.E. , Albano Joseph P. 
Published: August 2020

Abstract
Water management should be the foundation of container nursery production as it is linked directly to both water use and nutrient uptake efficiency and ultimately, environmental impact. In this study a gravimetric water management technique was used by means of a load cell/computer interface to determine irrigation volume and time of application. Cotoneaster dammeri ‘Skogholm’ was grown in 14 liter (#5) containers with an 8: 1 pine bark: sand mixture. The treatments were: an industry control that was irrigated cyclically at 1200, 1500, and 1800 HR to maintain a 0.2 LF (PM 0.2 LF); and a gravimetric treatment that irrigated when container capacity (CC) dropped below 94% and returned the CC to 98% with percentages lowered over the course of the season, always in a 4% spread, to maintain &lt; 0.15 LF (On Demand). The number of irrigation cycles were similar until the end of the study when On Demand cycled up to seven times a day. PM 0.2 LF had a greater WUEp (gram of dry weight produced per mL of water retained in the substrate). Time averaged application rate for On Demand was always lower than PM 0.2 LF resulting in a LF of 0.06 compared to 0.14 LF for PM 0.2 LF.
Cold Hardiness of Ilex glabra Cultivars from Field Trials and Laboratory Tests
Authors: Sun Youping , Zhang Donglin 
Published: August 2020

Abstract
To evaluate the cold hardiness of Ilex glabra (L.) A. Gray (inkberry) cultivars and provide growth and cold-hardiness data for growers as references for production and marketing, field trials and laboratory tests were conducted in 2007–2008 and 2008–2009. Plant survival was 72 and 93% for the 2007 and 2008 planting, respectively. Ilex glabra ‘Shamrock’ was the most cold-hardy cultivar; Ilex glabra f. leucocarpa, ‘Viridis’ and ‘Nigra’ were the least cold-hardy cultivars; and Ilex glabra wild species and its cultivars including ‘Compacta’, ‘Densa’, ‘Chamzin’, and ‘Pretty Girl’ had intermediate cold hardiness. Based on controlled freezing tests of Ilex glabra cultivars, the temperature that results in 50% relative electrical conductivity (REC50) of Ilex glabra cultivars ranged from −19.4 to −31.8C (−2.9 to −25.2 F) for January 2007 and−17.8 to −37.5C (−0.1 to−35.5F) for January 2008. The cold hardiness rates from field trials were significantly correlated with the REC50 values from laboratory tests. The factors influencing cold hardiness, including plant cultivar, tissue, temperature, deaacclimation, winter desiccation, and others (e.g. mechanical injury, snow pack) should be in consideration.
Extending Pine Bark Supplies with Wholetree and Clean Chip Residual Substrates
Authors: Murphy Anna-Marie , Gilliam Charles H. , Fain Glenn B. , Allen Torbert H. , Gallagher Thomas V. , Sibley Jeff L. , Marble Stephen C. , Witcher Anthony L. 
Published: August 2020

Abstract
A limited supply of pine bark (PB) over the past several years has caused concern among many nursery producers. In continuing the search for alternative substrates and working to quantify the extent to which substrates can be amended with high wood content alternatives, this study was developed to evaluate substrate treatments comprised of PB with 25, 50, and 75% clean chip residual (CCR) or WholeTree substrate (WT), as well as 100% substrates of each high wood fiber substrate. By 180 and 365 DAT, pH and electrical conductivity (EC) values for all treatments were similar to those of the 100% PB control. Growth data at 365 days after planting (DAT) showed that with all nursery crops tested, nursery producers could use 75% CCR or 75% WT in their standard PB substrate with limited impact on crop growth. The purpose of this study was to allow nursery producers the opportunity to become comfortable using CCR or WT as amendments before switching completely to 100% alternative substrates.
Cyclanilide Promotes Shoot Production and Flowering of Coreopsis and Coneflower during Nursery Production
Authors: Farris M.E. , Keever G.J. , Kessler J.R. , Olive J.W. 
Published: August 2020

Abstract
Herbaceous perennials were screened for increased branching and flowering in response to foliar sprays of cyclanilide (CYC), a plant growth regulator with cytokinin-like activity. Coreopsis verticillata ‘Creme Brulee’ (‘Crème Brulee’ coreopsis) and Rudbeckia fulgida ‘Goldsturm’ (‘Goldsturm’ coneflower), the only two species that responded positively to CYC, were used in subsequent experiments evaluating CYC concentration, method of application, and stage of plant development at application. Foliar sprays of 25 to 100 ppm CYC promoted increased shoot development, flowering, and plant width of coreopsis and coneflower, although flowering was delayed. Applying foliar sprays to both species when they were vegetative resulted in similar or more new shoots and flowers than an application when plants exhibited early signs of approaching flowering or at both stages. Increases in shoot counts from the application of substrate drenches of CYC to coreopsis and coneflower generally were less than from foliar sprays, while flower counts either decreased with increasing CYC concentration (coreopsis) or were unaffected (coneflower).
Evaluation of Selective Postemergence Herbicides for Yellow Nutsedge Control and Loblolly and Slash Pine Seedling Tolerance
Authors: Paul Jackson D. , Gilliam Charles H. , South David B. 
Published: August 2020

Abstract
Yellow nutsedge (Cyperus esculentus) is a difficult weed to control in conifer nurseries. Soil fumigation with methyl bromide has been used to control yellow nutsedge for years but may not be available in the future. For this reason, the objective of this research was to identify herbicides that can control yellow nutsedge but do not injure loblolly (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) when used over-the-top of seedlings. Yellow nutsedge tubers and loblolly and slash pine seedlings were potted separately, and treated with three rates of the herbicides mesotrione (Callisto®), imazosulfuron (Valent-V10142), and halosulfuron (Sedgehammer®). Imazosulfuron and halosulfuron provided the best suppression of nutsedge, but imazosulfuron injured loblolly and slash pine. Slash pine diameter and height growth were reduced by imazosulfuron. Halosulfuron did not affect loblolly pine but it reduced slash pine height growth and the number of new leaders (spring flush growth) the following spring. Mesotrione injured slash pine but provided intermediate control of yellow nutsedge. Halosulfuron applied at 35 to 140 g ai·ha−1 (active ingredient per hectare) over the top of loblolly pine (≥ 60 cm height and ≥ 8 mm diameter) can control yellow nutsedge without injuring pine seedlings.
Influence of Provenance and Fertilization in the Tree Nursery on Outplanting Performance and N-, P-, and K-Content of Viburnum opulus L. in Shoots and Roots
Authors: Bohne H. , Salomon L. , Gerhard D. 
Published: August 2020

Abstract
Two-year-old seedlings of two German provenances [Norddeutsches Tiefland (NT), Westdeutsches Bergland (WB)] of Viburnum opulus L. were cultivated in containers with ‘low’ and ‘high’ fertilization for one vegetation period and then transplanted into the field.
At the end of cultivation dry weight (dwt) of plants from NT was higher compared to WB. After outplanting NT maintained its higher dry weight of shoots. In the nursery only the dry weight of new shoots of NT increased due to the higher fertilization. Two years after outplanting the effect of high fertilization was still to be seen in higher dry weight of roots and old shoots for both provenances. At the end of cultivation high fertilization increased N-, P-, and K-concentration for WB in all plant compartments, but in NT only in roots. After outplanting % N decreased in all plant parts; % P and % K increased in new shoots and decreased in old shoots and roots. Retranslocation of N from the roots was higher for the previously high fertilized plants. For both fertilization levels retranslocation was slightly higher for the plants from WB.
Fertilization Affects Constitutive and Wound-Induced Chemical Defenses in Gerbera jamesonii
Authors: Spiers James D. , Davies Fred T. , He Chuanjiu , Starman Terri W. , Finlayson Scott A. , Senseman Scott A. , Heinz Kevin M. 
Published: August 2020

Abstract
The total phenolic content and jasmonic acid (JA) content of foliage from gerbera (Gerbera jamesonii ‘Festival Salmon’) subjected to low and high fertilization rates were measured to determine effects of fertilization on phytochemicals implicated in defense of insect pests. Gerbera seedlings were fertilized with low (only supplied with initial fertilizer charge present in professional growing media) or high (200 mg·liter−1 N; recommended rate) fertilization rates. Since JA is induced in response to wounding, treatments consisted of ± mechanical wounding with a hemostat to one physiologically mature leaf and the subsequent harvest of that leaf at specified time intervals (0, 0.5, 1, 3, and 10 h) for JA quantification. Total phenolic content was measured in mature and newly formed leaves. Plants receiving low fertility had reduced aboveground dry mass, were deficient in nitrogen and phosphorous, and had approximately a 9-fold higher concentration of total phenolics in mature leaf tissue compared to high fertility plants. Newly formed leaves had greater concentrations of phenolics than mature leaves in low fertility plants. In response to wounding, JA accumulation was more rapid and higher concentrations of JA were sustained longer in low fertility plants than in high fertility plants. These results show that altering fertilization does affect phytochemicals implicated in defense against insect pests, and these chemical defenses are increased in the foliage of low fertility gerberas.