bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of a Sib-mated Population of Buddleja davidii ‘White Bouquet’ × Buddleja indica Hybrids
Authors: Dunn Bruce L. , Lindstrom Jon T.
Published: August 2020

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

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

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

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 < 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

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

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

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

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 < 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

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

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

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

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

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

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.
Preliminary Study of Sodium Chloride Tolerance of Rudbeckia fulgida var. speciosa ‘Goldsturm’, Heuchera americana ‘Dale's Variety’ and Aquilegia × cultorum ‘Crimson Star’ Grown in Greenhouse Conditions
Authors: Gerber Carri , Deeter Laura , Hylton Kelsey , Stilwill Bryce
Published: August 2020

Heuchera americana ‘Dale's Variety’, Aquilegia × cultorum ‘Crimson Star’ and Rudbeckia fulgida var. speciosa ‘Goldsturm’ were grown in a soilless medium and watered weekly with either 0.00 (control), 0.05, 0.15 or 0.25 M NaCl solutions for 6 weeks. Foliage and leachate were analyzed for pH, Na+ and Cl−, and digital images were taken of all plants. Sodium and chloride concentrations in the leachate increased over time, while pH values remained unchanged. Aquilegia and Rudbeckia took up both Na+ and Cl−in increasing amounts over time. Heuchera took up large quantities of Cl−initially, but lesser amounts over time, and minimal Na+ into the foliage until the last week. At the highest treatment levels of NaCl, all plants showed significant visual damage. Aquilegia was the first to show visual damage at 0.05 M NaCl. Heuchera was intermediate in terms of symptom development. Based on the results of this study, Rudbeckia and Heuchera are listed as salt tolerant, and Aquilegia is listed as salt intolerant.
Branching of Photinia x fraseri in Response to Growth Regulators and Fertilizer
Authors: Ryan G.F.
Published: August 2020

Container grown photinia plants treated with 6-benzylamino purine (BA) or dikegulac (Atrinal) had 3 to 4 times as many branches as untreated plants. Branching was greatly increased by applying 10 to 15 gm (2-3 tsp) of Osmocote 18N-2.6P-10K (18-6-12) to supplement the fertilizer in the container mix. Application of Atrinal increased branching an additional 100% at the highest fertilizer level. Hand pinching the day before the first Atrinal application increased branching in one experiment, but hand pinching 11 days before the first Atrinal application had no effect on the response to Atrinal in another experiment. BA and N-(phenylmethyl)-9-(tetrahydro-2H-pyran-2-yl)-9H-purin-6-amine (Accel) increased branching when applied with Off-Shoot-O (OSO), and had less effect or no effect without OSO. Adding a phosphate buffer (Buffer-X) to prevent precipitation of BA further increased the response to the BA plus OSO treatment.
Effect of Time of Spacing on the Growth of Container-Grown Ilex cornuta ‘Dwarf Burford,’ Lindl. and Paxt., and Pittosporum tobira, Thumb.
Authors: Laiche Adolph J.
Published: August 2020

Ilex cornuta ‘Dward Burford,’ Lindl. and Paxt., and Pittosporum tobira, Thumb. liners were transplanted into unspaced (adjacent) black 15.2 cm (6 in) diameter containers and later spaced 30 cm (12 in) apart 0, 30,61 and 126 days after transplanting. Keeping plants can-to-can (unspaced) significantly reduced growing-media temperatures. Delaying spacing until required by crowding resulted in improved root and shoot growth in Pittosporum tobira and to a lesser degree in Ilex cornuta.
Potential of Fusilade, Poast and CGA 82725 for Control of Weedy Grasses in Woody Nursery Crops and Groundcovers
Authors: Rice R.P. , Lewis G. , Harrell K.
Published: August 2020

To assess crop safety, Fusilade (fluazifop-butyl), Poast (sethoxydim) and CGA 82725 (2-Propynyl 2-(4-([3,5-dichloro-2 pyridinyl] oxy) phenoxy) propanoate) were applied to nursery crops and groundcovers. Of the species tested, injury was minimal except on Juniperus horizontalis ‘Bar Harbor’ with both Fusilade (fluazifop-butyl) and CGA 82725 and on Carpobrotus edulis with Fusilade where serious injury occurred. In field tests, both Fusilade (fluazifop-butyl) and Poast (sethoxydim) controlled established bermudagrass (Cynodon dactylon) in both established and newly planted groundcovers and dichondra (Dichondra micrantha) without injury at 1.12 and 2.24 kg/ha (1.0 and 2.0 lb/A).
Influence of N, P and K Fertilizer Interactions on Growth of Ilex crenata Thunb. ‘Helleri’
Authors: Wright R.D. , Niemiera A.X.
Published: August 2020

Ilex crenata ‘Helleri’ was greenhouse-grown in sand culture for 8 weeks at 4 levels of N, P and K in a factorial arrangement. Nitrogen and K levels were maintained at 0, 25, 75, and 200 ppm and P at 0, 5, 15, and 40 ppm in the irrigation water. The lowest level of each nutrient required for optimal growth was 75 ppm N, 5-15 ppm P and 25 ppm K. When levels of P were maintained at 40 ppm, then 200 ppm K was required for maximum growth. The same trend occurred for N and P in that higher levels of N were required to promote maximum growth when P levels were at 40 rather than 15 ppm.
Growth of Scotch Pine Trees in Bluegrass Sod as Affected by Fertilizer Depth, Release Rate, and Season of Application
Authors: Hefley M.W.
Published: August 2020

Five-year-old Scotch pine (Pinus sylvestris L.) trees growing in bluegrass (Poa pratensis L.) sod were fertilized at two depths with liquid, granular, or compressed (Tree Stake) fertilizer. Trees were fertilized in the fall when dormant or in the spring when in active growth. Annual increase in trunk caliper was used to measure tree growth over two growing seasons. Increase in trunk caliper was least with liquid, greatest with compressed, and intermedidate with granular fertilizer. Granular and compressed fertilizer placed 15 cm (6 in) below the soil surface resulted in greater increase in trunk caliper than shallower placement. Liquid fertilizer placed shallow, which deposited some fertilizer at the soil surface, resulted in greater increase in trunk caliper than deeper placement. Spring fertilization resulted in greater increase in trunk caliper than fall fertilization, presumably because fertilizer nutrients were available during spring growth when the pines were able to absorb nutrients rapidly.
Influence of Light and Temperature on Germination of Sourwood (Oxydendrum arboreum (L.) DC.)
Authors: Barton S.S. , Bonaminio V.P.
Published: August 2020

Sourwood seed held at a constant temperature of 25°C (77°F) exhibited the highest germination percentage when exposed to 4 or more hours of light daily. There were no significant differences in germination percentages among seeds exposed to 4, 8 or continuous light during each 24 hour cycle. Seeds exposed to 1 hour of light daily and subjected to 20°C (68°F), 22.5°C (72.5°F), 25°C (77°F), 28°C (82.4°F), 25/15°C (77/59°F) or 30/20°C (86/68°F) exhibited the highest germination percentages at the alternating temperatures. Further, germination interval was shorter when seed were exposed to 30/20°C (86/68°F) than 25/15°C (77/59°P).
Mycorrhizal Status of Pines in Nurseries
Authors: Rupp L.A. , Mudge K.W.
Published: August 2020

Mycorrhizal status, soil and foliar nutrient status, and production histories were determined for Japanese black pine (Pinus thunbergiana Franco.) and dwarf Mugo pine (Pinus mugo Turra ‘mugo’) in 4 Long Island, New York nurseries. All pines sampled were mycorrhizal. No significant effect of age on percentage mycorrhizal roots was observed between 2-,3- and 5-year-old Japanese black pine. The extent of mycorrhizal formation with Mugo pine could not be correlated with differences in soil or foliar nutrient status among 3 field nurseries. However, field grown Mugo pine had approximately 20% more mycorrhizal roots (70%) than container grown plants (50%). A controlled greenhouse study of Mugo pine inoculated with the ectomycorrhizal fungus Pisolithus tinctorius (Pers. Coker and Couch) showed decreased mycorrhizal levels with increased N, suggesting that differences in mycorrhizal intensity between field and container grown nursery stock may have been related to differences in fertility.
Growth Response of Leyland Cypress to Media, N Application and Container Size After 1 and 2 Growing Seasons
Authors: Bilderback T.E.
Published: August 2020

Leyland cypress (X Cupressocyparis leylandii ‘Haggerston Grey’) cuttings were grown in 3.8 1 (#1), 7.6 1 (#2) and 11.4 1 (#3) containers in media combinations of pine bark, hardwood bark and coarse sand. Plants were fertilized with weekly applications of 200, 400, 600 or 800 ppm N. A growth index, percent foliar nitrogen, pH and soluble salts were detennined after 1 growing season and top dry weight was measured after 2 growing seasons. The 4 pine bark: 1 sand (v/v) and combination medium had lower pH values than the 4 hardwood bark: 1 sand medium. Percent foliar nitrogen ranged from 0.9% N to 1.34% N. Incremental N application did not increase N accumulation in leaf tissue. Increasing container size or N application did not increase the growth index through the fIrst growIng season. By the end of the second growing season plants in 11.4 1 containers were larger than those in 3.8 1 containers.
Growth of Foliage Plants in Composted Raw Sewage Sludge and Perlite Media
Authors: Marcotrigiano M. , Gouin F.R. , Link C.B.
Published: August 2020

Raw sewage sludge compost was tested as a major component of media for the production of foliage plants. Each of 4 previously screened compost fractions was blended with 0, 20, 40 or 60% perlite (v:v) and to half the pots a slow release fertilizer was added. Top dry weight of Tradescantia fluminensis (Wandering Jew) was greatest in mixes with low soluble salt levels and high levels of air-filled pore space. Mixes exhibiting these qualities contained a high percentage of perlite and/or large compost particle sizes. Fertilizer application did not significantly increase dry weights. In a second experiment, Plectranthus australis (Swedish Ivy), Tolmiea menziesii (Piggyback), Sedum lineare var. variegatum (Star Sedum), and Wandering Jew were grown in commercial mixes and 2 superior sludge compost-perlite mixes (SP) at 3 fertilizer levels. While all species grew well in commercial mixes, in SP mixes growth was comparable only for Wandering Jew or for Swedish Ivy or Sedum grown in the coarser compost mixture.
Response of Podocarpus macrophyllus to Rock Phosphate and Mycorrhizae
Authors: Yeager Thomas H. , Johnson Charles R.
Published: August 2020

Shoot and root dry weights of greenhouse-grown mycorrhizal and nonmycorrhizal Podocarpus macrophyllus were not different after 8 months. Shoot dry weights were not different for plants grown in the 2 pine bark: 1 moss peat: 1 sand (v/v/v) medium amended with Florida rock phosphate (14% P) at either 0.54, 1.08, 2.16, 4.32, or 8.64 mg P/cm3 (14.5, 29, 58, 116, or 232 oz P/yd3, respectively) of medium (2300 cm3/container) or 0.27 mg P/cm3 (7.25 oz P/yd3) from superphosphate (9% P). Root dry weights for plants grown without a P amendment were greater than for plants grown with rock phosphate amendments of 0.54 and 1.08 mg P/cm3. Growing medium extract P levels 51 days after potting and thereafter were 2 ppm or less for the rock phosphate treatments, while P levels for the superphosphate-amended mediunl decreased from 169 ppm on day 51 to 9 ppm on day 236. Phosphorus accumulated by shoot and root tissues exhibited a similar relationship to shoot and root dry weights.
Auxinic Herbicide Phytotoxicity to Container-Grown Muhlenbergia capillaris and Miscanthus sinensis
Authors: Neal Joseph C. , Wolfe Joseph C. , Harlow Christopher D.
Published: August 2020

Phytotoxicity of postemergence applications of auxinic herbicides was evaluated on container-grown Miscanthus sinensis ‘Gracillimus’ and Muhlenbergia capillaris. Treatments included Triamine II (MCPA, mecoprop-p and dichlorprop-p), Tri-Power (MCPA, mecoprop-p and dicamba), and Triplet Low Odor (2,4-D, mecoprop-p and dicamba), each applied at the labeled dose, twice the labeled dose, or four times the labeled dose. Liners established in 32-cell trays were transplanted to 3-L containers. About two weeks after transplanting, treatments were applied to actively growing plants and re-applied about six weeks later. The experiment was conducted in 2010 and repeated in 2011. Miscanthus was uninjured following a single application at the labeled dose, but following a second application all treatments were injurious in one of two years. Foliage fresh weight was generally not reduced by auxin herbicides, but the number and weight of inflorescence stalks were reduced by all herbicides and doses. Muhlenbergia was injured by twice and four times the labeled doses of all herbicides in both years and by the labeled doses in one year. All herbicide treatments reduced Muhlenbergia inflorescence counts and above-ground fresh weights.
Container-grown Shrubs Respond Differently to Controlled-release Fertilizer Rates in a Temperate Climate
Authors: Clark Mary Jane , Zheng Youbin
Published: August 2020

To determine the response of container-grown shrubs to controlled-release fertilizer (CRF) rate when grown in a temperate climate, Polyon® 19–04–10 + Minors, an 8–9 month CRF, was incorporated into growing substrates for ‘Gro-Low’ fragrant sumac (Rhus aromatica Aiton), ‘Goldmound’ spirea (Spiraea × bumalda Burv.) and ‘Bloomerang’® purple lilac (Syringa × ‘Penda’) transplants. Also, a 15–06–11 + Micros, a 10–12 month CRF, was incorporated into growing substrates for ‘Green Mound’ boxwood (Buxus × ‘Green Mound’), ‘Runyan’ yew (Taxus × media) and ‘Emerald’ white-cedar (arborvitae) (Thuja occidentalis L.) transplants, at six rates (0.15, 0.45, 0.75, 1.05, 1.35 and 1.65 kg·m−3 N; 0.25, 0.76, 1.26, 1.77, 2.28 and 2.78 lb·yd−3 N). We observed greater growth index, leaf area, and shoot dry weight at high vs. low CRF rates for the majority of species. Nutrient deficiency symptoms such as light green leaves were observed at low CRF rates for some species, including fragrant sumac, lilac and white-cedar. Optimal species-specific CRF application rates were 1.05 kg·m−3 N (1.77 lb·yd−3 N) for lilac and yew and 0.45 kg·m−3 N (0.76 lb·yd−3 N) for boxwood and white-cedar, while the optimal CRF ranges were 0.75 to 1.35 kg·m−3 N (1.26 to 2.28 lb·yd−3 N) for fragrant sumac and 0.75 to 1.05 kg·m−3 N (1.26 to 1.77 lb·yd−3 N) for spirea. Adjusting CRF application rates based on plant response may provide nursery growers with an efficient tool for managing nursery crop growth and production timing in the temperate climate.
Bulking Duration and Daminozide Affect Growth and Flowering of Achillea ×‘Coronation Gold’
Authors: Li Mohan , Kessler J. Raymond , Keever Gary J. , Foshee Wheeler G.
Published: August 2020

A study was conducted to determine the effects of bulking duration and the plant growth retardant daminozide on plant growth and flowering of greenhouse-grown ‘Coronation Gold’ yarrow (Achillea ×‘Coronation Gold’). Single-shoot liners of yarrow were transplanted on October 14 and December 2, 2010, into 15 cm (6 in) containers and bulked for 4, 6, 8, or 10 weeks prior to exposure to night-interrupted lighting (NIL). Increasing the bulking duration increased the number of shortened, thickened stems of rosette-like appearance, or offsets, that had developed from the base of the main stem by the end of bulking by 100 to 367% and reduced days to first and five open inflorescences, hereafter referred to as flowers, from the beginning of NIL by 13 to 16 days and 10 to 20 days for the October and December potting dates, respectively. Increasing the bulking duration increased flower and flower bud number by 67 and 25% in the October 14 and December 2 potting dates, respectively. Therefore, more flowers and flower buds formed on yarrow when potted early, compared to late potting. Lengths of the first five open flower stems were inconsistent and minimally affected by bulking duration. In a repeat of the experiment potted on December 2 using the same bulking treatments, 5,000 ppm of daminozide was applied as a foliar spray when half the plants in a bulking duration had begun to elongate and was reapplied 1 week later. Daminozide application decreased stem length at first open flower by 20 to 43%, but increased days to first flower and five open flowers by 6 and 8 days, respectively. As in the first experiment, increasing the bulking duration increased the number of offsets and flower and flower bud number and reduced days to first and five open flowers.
Production and Marketing Practices and Trade Flows in the United States Green Industry in 2013
Authors: Hodges Alan W. , Khachatryan Hayk , Palma Marco A. , Hall Charles R.
Published: August 2020

A national survey of 32,000 U.S. ornamental plant grower and dealer-retail firms was conducted to collect information on business practices and operating results for calendar year 2013. A total of 2,657 valid respondent firms reported annual sales of $3.957 billion, and employment of 38,657 fulltime, part-time, seasonal and foreign H2A workers. About 43 percent of sales were at retail to final consumers, and 57 percent through wholesale market channels, including landscape contractors, re-wholesalers, home centers, garden centers and mass merchandise stores. The top five specific plant categories reported were flowering annuals (bedding plants), deciduous shade and flowering trees, herbaceous perennials, deciduous shrubs, and vegetables/fruits/herbs. Container-grown plants were the predominant product form. Sales were reported for marketing practices such as advance contracting, brokerage, and transaction methods such as telephone or in-person sales. The internet was the largest advertising medium. International exports were a small share of total sales (<1%), while sales outside the production area for eight agroclimatic regions of the United States represented less than one percent to 36 percent of sales. Groundwater wells were the predominant source of irrigation water, and overhead sprinklers were the largest application method, followed by drip irrigation and hand watering. Factors perceived to be most important for the overall health of the green industry included market demand and weather uncertainty.
Rooting Stem Cuttings of Herbaceous and Woody Ornamentals in Substrates Containing Eastern Redcedar (Juniperus virginiana)
Authors: Brock Justin A. , Griffin Jason J. , Boyer Cheryl R.
Published: August 2020

Propagation substrates can strongly influence rooting success of stem cuttings. Eastern redcedar (Juniperus virginiana L.) chips (ERC) have been suggested as a propagation substrate component. This study investigated ERC as a perlite substitute in a perlite:sphagnum peat moss (3:1 v/v) rooting substrate. Stem cuttings of coleus [Solenostemon scutellarioides (L.) Codd], English ivy (Hedera helix L.), forsythia (Forsythia ×intermedia Zab.), lantana (Lantana camara L.), and spreading euonymus (Euonymus kiautschovicus Loes.) were rooted in substrates containing increasing concentrations of ERC hammer-milled to pass a 4.8 mm (0.19 in) screen. All species rooted well (≥ 95%) in all substrates except forsythia which rooted poorly in all substrates (8 to 36%). ERC concentration did not affect mean root number or mean root length in any species except spreading euonymus where mean root number peaked at 0 and 100% ERC content and mean root length decreased with increasing ERC content. Bulk density, container capacity, and total porosity increased as ERC replaced perlite. Physical properties of all substrates were suitable for cutting propagation. ERC can effectively replace perlite in rooting substrates for many ornamental species.
Local Adaptation? — Physiological and Biochemical Responses of four Hazelnut Populations to Drought and Possible Impacts on Tree Nurseries
Authors: Wanjiku James Gacheru , Bohne Heike
Published: August 2020

Outplanting performance of trees and shrubs cultivated in tree nurseries is assumed to be better if propagation material is sourced from the designated areas of future growth. However, this requires a local nursery to produce that cultivar, which might reduce the availability of that species. In this study we evaluated drought reactions of 2.5-year-old hazelnut (Corylus avellana L.) from four population origins. After container cultivation, plants were subjected to drought by irrigating 25% (fast stress) or 50% (slow stress) of the lost water. Control plants were well irrigated. Depending on stress development and hence stress duration, different physiological (stomatal conductance, predawn water potential, relative water content) and biochemical (glucose, fructose, sucrose, starch, proline) responses to drought were found. Independent of stress development, only few differences among populations were found. These differences were mostly not related to precipitation in their area of origin, suggesting no local adaptation within the ecological range investigated.
How Green Are Trees? — Using Life Cycle Assessment Methods to Assess Net Environmental Benefits
Authors: Petri Aaron C. , Koeser Andrew K. , Lovell Sarah T. , Ingram Dewayne
Published: August 2020

This study used life cycle assessment methods (LCA) to assess the carbon footprint of an urban tree from propagation to disposal, expanding on recent works focused primarily on inventorying the inputs for woody ornamental nursery production. Urban forest managers from the Chicago metropolitan area were surveyed on their plant selection, planting, maintenance, removal, and disposal practices to generate the model inputs. Alterations to management practices such as the pruning cycle can significantly reduce the age at which a tree changes from being a carbon emitter to being carbon neutral. Highly mechanized tree care practices extend the time to 33 years whereas less mechanized scenarios are 26 years. An annual windshield survey conducted by many municipalities will extend this period by two to three years. Results of this work offer a more accurate assessment of ecosystems services offered by urban forests and serve as a first step in identifying tree care practices which offer an optimal environmental return on investment.
Identifying the Optimal Application Rate of Three Fertilizers Used to Grow New Guinea Impatiens
Authors: Ostrom A.K. , Pasian C.C.
Published: August 2020

This manuscript describes the effect of controlled-release, and water-soluble fertilizers on the growth and quality of New Guinea impatiens (NGI) (Impatiens hawkeri Bull.). Three different fertilizers were applied at three rates each in order to investigate their effect on growth and quality of ‘Paradise New Red.’ NGI. Fertilizer treatments included 1) a 20-4.4-16.6 water-soluble fertilizer (WSF), 2) a 10-1.8-2.5 soybean-based fertilizer (SBF), and 3) a 15-4-10, three-to four-month longevity controlled-release fertilizer (CRF). CRF was applied as a pre-plant at 1×, 0.75×, and 0.5× the label rate. WSF and SBF fertigation rates of 75, 150, and 250 mg·L−1 N (75, 150, and 250 ppm N), respectively, were used based on a common range of fertigation rates in a greenhouse setting from what is considered relatively low, moderate, and high for NGI production. Plants were irrigated or fertigated by hand every 1 to 5 days as needed, based on environmental conditions and plant size, with either approximately 300 mL (10.4 oz) of either tap water or a fertilizer solution. SPAD readings, above ground plant weight, consumer preference ratings, and cumulative flower number were measured and used to calculate a quality index (QI). Optimal fertilizer rates as determined by the QI were found to be 1) CRF at 7.11 kg·m−3 (11.8 lb·yd−3), 2) SBF at 150 mg·L−1 (150 ppm) N, and 3) WSF at 75 mg·L−1 (75 ppm) N. With the application method used in this work, the WSF was more efficient than the SBF because it produced high quality plants with less fertilizer applied. While for the most part overall consumer preference ratings coincided with plant dry weight, there were some exceptions, indicating that consumers can prefer plants that are not necessary the largest as indicated by their dry weights. Consumer preferences may not coincide with typical plant parameters of plant growth all the time. Consumer preferences should be always considered in an industry that sell its products based mainly on their appearance.
Residues of neonicotinoid insecticides in pollen and nectar from model plants1
Authors: Cowles Richard S. , Eitzer Brian D.
Published: August 2020

Systemic insecticides used for ornamental horticulture crops can protect all portions of a plant with long-lasting effects. However, they may be hazardous to pollinators foraging on contaminated nectar or pollen. Two model plant cultivars were chosen based upon their ability to produce large quantities of pollen or nectar, enabling examination of the level of nectar or pollen contamination (e.g., insecticide “residues”) following insecticide treatments, rather than for the need or advisability to treat these plants in production nurseries or the landscape with systemic insecticides. These plants were sunflower (Helianthus annuus L. ‘Taiyo') for pollen, and swamp milkweed (Asclepius incarnata L. ‘Ice Ballet') for nectar. Plants were treated at labeled nursery rates with imidacloprid, dinotefuran, or thiamethoxam via foliar spray or soil drench at various times before bloom. Insecticide residues from pollen and nectar varied based upon application method, insecticide, and rate. Assuming that residues should be considered hazardous when they exceed 25 parts per billion (ppb) for nectar or 100 ppb for pollen, potentially bee-toxic concentrations of insecticide in sunflower pollen only followed high-rate drench treatments. Toxic concentrations of neonicotinoids were found in milkweed nectar when applied either as a drench or as a foliar spray up to six weeks before bloom. Label directions for nursery and greenhouse plants permit very high application rates relative to agronomic crops. These high rates can create hazardous conditions for pollinators, and should be avoided for ornamental crops that are highly attractive to bees.

Index words: sunflower (Helianthus annuus L.); swamp milkweed (Asclepius incarnata L.); dinotefuran; imidacloprid; thiamethoxam; pollinator; systemic insecticides.

Chemicals used in this study: dinotefuran (Safari 20 SG); imidacloprid (Xytect 2F); thiamethoxam (Flagship 25 WG).

Species used in this study: sunflower (Helianthus annuus L.); swamp milkweed (Asclepius incarnata L.).