bluuebunny/crossref_metadata_2025 huggingface dataset:
Below Ground Pot-in-Pot Effects on Growth of Two Southwest Landscape Trees was Related to Root Membrane Thermostability
Authors: Martin Chris A. , McDowell L. Brooke , Bhattacharya Shiela
Published: August 2020

Two southwestern desert landscape trees, Acacia smallii L. (sweet acacia) and Cercidium floridum Benth. ex A. Gray (blue palo verde), were grown outdoors in full sun during Summer 1997 in 19-liter (#5) containers placed either pot-in-pot (PIP) below ground or unshielded in above-ground containers (AGC). Soil moisture sensors wired to electronic solenoid valves regulated occurrence of six cyclic micro-irrigation pulses per day (0600, 0900, 1200, 1500, 1800, and 2100 HR) such that container substrate moisture tensions were continuously maintained between −0.005 to −0.01 MPa (90% of water holding capacity) in both PIP and AGC. Mean maximum recorded root-zone temperatures in PIP containers were 19C (34F) lower than for AGC. Micro-irrigation volumes were 40% less for trees grown PIP compared with those in AGC. Growth of sweet acacia was enhanced by PIP placement while in containers and one year after transplanting trees into field plots in 1998. Only caliper growth of blue palo verde was increased by PIP placement while in containers, but had no effect on blue palo verde growth one year after transplanting into field plots. The critical killing temperature (TM) for root tissues of sweet acacia and blue palo verde were 45.3 ± 1.8C (113.5 ± 3.2F) and 49.4 ± 0.8C (120.9 ± 1.4F), respectively, indicating differences in root membrane thermostability. Based on our data, we suggest that sweet acacia trees benefitted from PIP placement more than blue palo verde trees because root-zone temperatures in PIP containers were lower than for AGC in central Arizona, and sweet acacia roots were more susceptible to injury by supraoptimal root zone temperatures.
Chilling Effects on Shoot Emergence and Subsequent Growth in Hosta
Authors: Keever Gary J. , West Mark S. , Kessler J. Raymond
Published: August 2020

Two hosta cultivars, ‘Francee’ and ‘Frances Williams’, were chilled for 0 to 16 weeks at 4C (39F) prior to forcing in a heated greenhouse. As chilling duration increased, times to shoot emergence and first unfurled leaf and days gained in shoot emergence time per day of chilling decreased at a decreasing rate, leaf area index (length × width) of the first unfurled leaf increased at a decreasing rate and shoot dry weight increased linearly. Shoots of non-chilled plants of ‘Francee’ emerged an average of 32 days before those of ‘Frances Williams’. In ‘Francee’ chilled for 0 and 2 weeks, 30% and 10% of plants, respectively, failed to emerge shoots and 60% and 10% failed to unfurl a leaf. In ‘Frances Williams’ chilled for 0, 2 and 4 weeks, 60%, 30% and 50% of plants, respectively, failed to emerge shoots and 80%, 30% and 50% failed to unfurl a leaf. All plants of both cultivars chilled for longer durations emerged shoots and unfurled at least one leaf.
Two Early Nodulation Genes are not Markers for the Capacity of Leguminous Nursery Crops to Form Root Nodules
Authors: Graves William R. , Foster Carol M. , Rosin Faye M. , Schrader James A.
Published: August 2020

Little is known about mechanisms that permit or prevent formation of root nodules in which nitrogen gas (N2) is fixed by rhizobial bacteria in association with nursery crops in the legume family. We tested the hypothesis that two genes associated with the fixation of N2 could be used as markers of nodulation capacity among legumes because they occur only in species that can form functional nodules. The presence of ENOD2 and ENOD12 was tested in genomic DNA from three non-nodulating legumes [Cercis canadensis L. (eastern redbud), Gleditsia triacanthos L. var. inermis Willd. (thornless honeylocust), Gymnocladus dioicus (L.) K. Koch (Kentucky coffeetree)] and two nodulating legumes [Albizia julibrissin Durazz. (silk-tree), Laburnum alpinum (Mill.) Bercht. & Presl. (Scotch laburnum)]. Southern analyses indicated that ENOD2 is present in thornless honeylocust, Kentucky coffeetree, and Scotch laburnum, and that ENOD12 is present in eastern redbud, thornless honeylocust, and Scotch laburnum. These results diversify the group of nodulating legumes in which ENOD2 and ENOD12 have been found and show these genes also occur in legumes considered incapable of nodulation. We conclude that neither gene can be used to screen existing or new leguminous nursery crops for the capacity to form N2-fixing nodules.
Low Irradiance During Rooting Improves Propagation of Oak and Maple Taxa
Authors: Zaczek J. J. , Heuser C. W. , Steiner K. C.
Published: August 2020

Rooting trials were conducted to determine if the duration of exposure to low levels of solar irradiance during root initiation influenced rooting and survival of semihardwood cuttings of six tree species. Cuttings of oak (Quercus imbricaria, Q. nigra, Q. palustris, Q. rubra) and maple (Acer rubrum ‘Bowhall’, and A. truncatum) were treated with IBA and placed in a fog-humidified polyethylene tent rooting chamber for 119 or 117 days (A. rubrum and Q. nigra) under either 82% (control) or 93% (low irradiance) shading of ambient outdoor solar radiation. Cuttings were exposed to either 0, 10, 20, 40, or 119 days of 7% irradiance followed by placement under control conditions (18% irradiance) for the remainder of the treatment. Percentage rooting, the number of roots per cutting, and the number of days to root were significantly influenced by exposure to 7% irradiance during rooting, but responses were dependent on taxa. For most taxa, the highest rooting percentages required at least 10 days of exposure to 7% irradiance. Overwinter survival of rooted cuttings averaged 58.8% and was not affected by treatment. Results of this study demonstrate that low irradiance in the rooting environment can increase the rooting of cuttings of oak and maple taxa.
Characteristics of Horticultural Distribution Centers
Authors: Garber M.P. , Bondari K.
Published: August 2020

A national survey of Horticultural Distribution Centers (HDCs) resulted in a 32.3% response rate with owners representing 68% of respondents. The greatest number of respondents were from the Northeast and firms have been in business from 3 to 115 years for an average of 26.5 years. About one-fourth of the firms surveyed (27.4%) were engaged only in distribution activity. However, for all firms, distribution activity accounted for over half (54.2%) of their revenue. The average HDC had annual revenue of $3.4M. The mean number of full-time employees was about 33, with an additional 16 part-time hourly. Average hourly compensation rate ranged form $15.67 for manager/supervisor to $10.58 for staff and $8.94 for full-time hourly workers. Data were analyzed by region of the country and regional differences are discussed.
Improvement of Rhododendron and Forsythia Growth with Buffered-Phosphorus Fertilizer
Authors: Brown Kathleen M. , Miller Carter R. , Kuhns Larry , Beattie David J. , Lynch Jonathan P.
Published: August 2020

Rhododendron and forsythia plants were grown in a soilless medium containing one of four phosphorus treatments: soluble P, slow-release P, or 0.5% or 1% solid-phase alumina-buffered P (Al-P). Soluble phosphorus concentrations in the leachate were highest for soluble-P treatment and lowest for the Al-P treatments. Al-P supplied adequate P for plant growth throughout the season while substantially reducing P leaching. Forsythia plants produced more shoot dry mass when grown with 0.5% Al-P than with the other treatments, and larger rhododendron plants were produced when fertilized with 1% Al-P.
Seed Germination of Two Provenances of Atlantic White-Cedar as Influenced by Stratification, Temperature, and Light
Authors: Jull Laura G. , Blazich Frank A. , Hinesley L. Eric
Published: August 2020

Seeds from two provenances (Wayne Co., NC, and Escambia Co., AL) of Atlantic white-cedar [Chamaecyparis thyoides (L.) B.S.P.] were stratified (moist-prechilled) for 0, 30, 60 or 90 days at 4C (39F). Following stratification, seeds were germinated at 25C (77F) or 8/16 hr thermoperiods of 25/15C (77/59F) or 30/20C (86/68F) with daily photoperiods at each temperature of total darkness, ½, 1,2, 4, 8, 12, or 24 hr. Seed germination of the Alabama provenance was greater than the North Carolina provenance for all treatments. There were no significant differences in percentage germination between 25/15C (77/59F) and 30/20C (86/68F) for any durations of stratification for either provenance. Regardless of stratification, germination was lowest at 25C (77F) for both provenances. When nonstratified seeds from the North Carolina provenance were germinated at photoperiods ≤ 12 hr, total germination never exceeded 5%, indicating an obligate light requirement. On the other hand, an obligate light requirement was not observed for seeds from the Alabama provenance since 15% of the nonstratified seeds germinated in darkness. However, for both provenances, stratification and daily photoperiods ≥ ½ hr greatly increased germination. The North Carolina provenance required 90 days stratification to maximize germination (66%), whereas the Alabama provenance needed only 30 days (80%). High germination percentages were due, in part, to rigorous seed cleaning.
Evaluation of Herbicides for Phytotoxicity to Rose Plants and Efficacy
Authors: Gonzalez Martha P. , Karlik John
Published: August 2020

Roses frequently occur in gardens and landscapes and may require weed management. Herbicide trials were conducted with 10 herbicides applied at label rates to plots containing a hybrid tea rose cultivar. The primary objective was to evaluate injury to rose plants when herbicides were sprayed over-the-top at two stages of growth: bud break and full leaf. A secondary objective was to evaluate the efficacy of the herbicides. The soil residual (pre-emergent) herbicides Devrinol (napropamide), Goal (oxyfluorfen) and the dinitroaniline herbicides Surflan (oryzalin), Treflan (trifluralin) and Prowl (pendimethalin) did not injure roses when applied at bud break. The herbicides Ornamec (fluazifop-p-butyl), Poast (sethoxy dim) and Envoy (clethodim), which have post-emergent activity, also did not injure roses when applied to roses at bud break or when applied in late spring when plants had fully developed leaves. Roses oversprayed at bud break with the herbicides Roundup (glyphosate) and Trimec Classic (2,4-D + MCPA + dicamba) did not show phytotoxicity symptoms immediately after application but had significantly shorter shoots beginning six weeks after treatment (WAT). Roses with fully developed leaves which were oversprayed with Roundup and Trimec Classic did show symptoms of injury one WAT and thereafter.
A Regional Survey of Deer Damage Throughout Northeast Nurseries and Orchards
Authors: Lemieux Nicole , Maynard Brian K. , Johnson William A.
Published: August 2020

In order to quantify the regional perspective on deer damage, a survey was sent to growers throughout nine Northeast states (ME, NH, VT, MA, CT, RI, NY, NJ, and PA). The objective of the survey was to assess the extent of damage, economic impact, plants damaged, control methods used, and efficacy of control methods. After excluding those surveys that were returned as undeliverable mail (n = 103), a total of 341 (30%) responded. Of the respondents, 65% reported that deer damage was a problem at their nursery. Forty-seven (14%) respondents reported $10,000 or more in plant losses during 1996. The majority of the damage was due to browsing by deer (59%), while rubbing (33%) and trampling (8%) were less common. Plants damaged included yews (Taxus spp.), arborvitae (Thuja spp.), and fir (Abies spp.), various shade trees, hosta (Hosta spp.) and English ivy (Hedera helix). Most respondents (66%) with a deer damage problem utilized one or more methods of control. Repellents (66%) and fencing (56%) were the most common methods used to minimize damage. Forty percent of respondents using fencing reported fencing to be ‘very’ or ‘somewhat’ effective.
Evaluation of Commercial Deer Repellents on Ornamentals in Nurseries
Authors: Lemieux Nicole C. , Maynard Brian K. , Johnson William A.
Published: August 2020

The efficacy of several new commercial deer repellents in a nursery setting was evaluated from October through March. Repellents evaluated were Deer-Away™, Tree Guard™, Holly Ridge, Bobbex™, and Deer-Off™. Damage was evaluated on yew (Taxus x media L. ‘Densiformis’, Taxus x media Rehd. ‘Nigra’, Taxus baccata Rehd., and Taxus baccata L. ‘Repandens’), holly (Ilex x meserveae S.Y Hu ‘Blue Princess’ and Ilex x meserveae S.Y Hu ‘China Girl’) and Juniper (Juniperus chinensis L. ‘Keteleeri’). Plots received between 0% and 96% deer browse damage. Both Deer Away™ and Holly Ridge significantly reduced browsing. Tree Guard™ and Deer Off™ reduced browsing when feeding intensity was low.
Leaching of Nitrogen from Container Plants Grown under Controlled Fertigation Regimes
Authors: Andersen Lillie , Hansen Conny Wang
Published: August 2020

One-year-old Weigela and Campanula liners were transplanted into containers and grown outdoors for one season. Nutrient solutions with high conductivity (EC: 2.0 dS/m), intermediate conductivity (EC: 1.25 dS/m) or low conductivity (EC: 0.95 dS/m) were applied at each irrigation. The nitrogen concentrations of the solutions were 220, 110 and 55 g N/m3, respectively. Fertigation frequency was controlled by the use of tensiometers placed in the growing medium. Growth and the amount of N leached from the containers and the N content of the shoot were measured. The respective amounts of N leached from Weigela were 40, 6 or 3 kg N/ha, whereas in Campanula 88, 45 or 17 kg N/ha was leached. The recovery of nitrogen applied was between 53% to 73% in Weigela and 41% to 56% in Campanula. The amount of non-recovered nitrogen was substantially higher in treatments 1.25 dS/m and 0.95 dS/m than in 2.0 dS/m. Fresh and dry weights of both plant species and the number of flowers in Campanula were reduced when the plants were grown at low conductivity.
Micropropagation of Betula platyphylla ‘Fargo’ via Shoot Tip Culture and Regeneration from Leaf Tissues
Authors: Cheng Zong-Ming , Schnurr Jeffrey P. , Dai Wenhao
Published: August 2020

A micropropagation system was developed for mass propagation of ‘Fargo’® (Dakota Pinnacle™), a newly released cultivar of Asian white birch (Betula platyphylla). Shoot tips from the mature, 7-year-old tree were established on 75% strength Murashige and Skoog medium supplemented with 0.1 μM thidiazuron. The greatest shoot proliferation occurred on Woody Plant Medium supplemented with 2.2 μM benzyladenine (BA), solidified with 6.5 g/liter agar, and cultured at 24C (75F). Microshoots were rooted in vitro or ex vitro followed by establishment in the greenhouse. A system to regenerate plantlets from leaves of aseptically cultured shoots was also developed. The optimum conditions for shoot regeneration from leaves included a 2-week dark treatment before exposure to a 16/8 hour light/dark photoperiod, use of large and healthy leaf explants, and culture on the Woody Plant Medium containing 20.0 or 30.0 μM BA. The regenerated shoots proliferated on the micropropagation medium and were divided, and the resulting shoots were rooted ex vitro and acclimated in greenhouse conditions.
Changes in Root IAA Content and Growth of Bareroot Conifers Treated with Plant Growth Regulating Substances at Planting
Authors: Scagel C.F. , Linderman R.G.
Published: August 2020

Growth and survival of bareroot plants after transplanting is partially a function of the plant's capacity to produce new roots. We conducted an experiment to determine whether application of plant growth regulators (PGRs) or moisture retention materials could modify IAA concentration in roots, new root growth, and above ground plant growth. Bareroot western larch, Englemann spruce, lodgepole pine, and Douglas-fir were treated with Stimroot, ethrel, Hormogel, or Alginate immediately before planting into a raised bed in a greenhouse. All treatments increased IAA content in roots of western larch, Englemann spruce, and Douglas-fir, but only treatments containing IBA increased free IAA in roots of lodgepole pine. Stimroot and Hormogel treatment increased height growth of western larch, lodgepole pine, and Douglas-fir, but only ethrel treatment increased height growth of Englemann spruce. All treatments increased stem diameter growth of western larch. Stimroot increased stem diameter growth rate of Englemann spruce and Douglas-fir, but stem diameter of lodgepole pine was unaffected by all treatments. Our results indicate that application of PGRs or other root-promoting materials to the roots of bareroot conifers before planting has the potential to be a cost-beneficial method for increasing root growth and decreasing transplant shock.
Effect of Bittercress Size and Gallery Rate on Postemergence Bittercress Control
Authors: Altland James E. , Gilliam Charles H. , Edwards James H. , Keever Gary J. , Kessler J. Raymond , Eakes D. Joseph
Published: August 2020

Two experiments were conducted to evaluate the effect of Gallery (isoxaben) rate and hairy bittercress (Cardamine hirsuta L.) size on postemergence bittercress control and subsequent preemergence bittercress control. Treatments included Gallery applied at 0.56, 1.12, and 2.24 kg ai/ha (0.5, 1.0, and 2.0 lb ai/A), Image (imazaquin) applied at 0.070 kg ai/ha (0.06 lb ai/A), and a non-treated control. Treatments were applied to bittercress characterized as either small, intermediate, or large. A Gallery rate × bittercress size interaction for postemergence bittercress control was observed in experiment 1. At 28 days after treatment (DAT), the lowest Gallery rate [0.56 kg ai/ha (0.5 lb ai/A)] provided less than 40% control across all bittercress sizes; the middle Gallery rate provided 90% bittercress control of small and intermediate size bittercress but only 43% control of large bittercress, and the high Gallery rate provided 86 to 91% bittercress control across all bittercress sizes. At 28 DAT, control increased linearly with increasing Gallery rate in large bittercress, and linearly and quadratically in small and intermediate sized bittercress, respectively. There were no interactions in experiment 2; however, Gallery rate and bittercress size main effects were significant. At 14 DAT, bittercress control increased linearly with increasing Gallery rate. Across all rates, Gallery provided 92% control of small bittercress, 71% control of intermediate bittercress, and only 48% control of large bittercress. In both experiments, Image provided 92 to 100% bittercress control of small and intermediate bittercress, and 83 to 96% control of large bittercress. Gallery provided better subsequent preemergence bittercress control with fewer bittercress per container at 60 DAT when applied to small or intermediate sized bittercress than when applied to large bittercress (experiment 2). ‘Natchez’ crapemyrtle was not affected by any treatment.
Occurrence of Dogwood Anthracnose, Spot Anthracnose, and Botrytis Blight in Native Stands of Flowering Dogwood in North Alabama
Authors: Hagan Austin , Mullen Jackie
Published: August 2020

In North Alabama, dogwood anthracnose (Discula destructiva) was the most common and damaging disease identified in stands of native flowering dogwood (Cornus florida). In the spring of 1992 and 1993, this disease was observed at 59% and 64%, respectively, of the forest and park sites surveyed. Highest incidence and severity of dogwood anthracnose was recorded in the Appalachian Mountains and adjoining foothills of the Piedmont at elevations of 372 to 558 m (1200 to 1800 ft) in the northeastern corner of Alabama near Georgia and Tennessee. At selected sites in Cherokee, Cleburne, DeKalb, Jackson, and Madison Counties, approximately 90% to 100% of the trees examined displayed diagnostic symptoms of dogwood anthracnose. Extensive blighting of the leaves, shoot dieback, epicormic shoot formation, and sometimes tree death were noted. Lower levels of anthracnose damage were recorded on trees in several additional counties in northeast Alabama. Survey results indicate that this disease has not spread onto flowering dogwood in other counties in North Alabama. Spot anthracnose (Elsinoe corni) and Botrytis blight (Botrytis cinerea) were found far less frequently and at fewer locations on flowering dogwood than dogwood anthracnose. Typically, damage attributed to either disease was unobtrusive and of little threat to tree health.
Wiregrass Tubeling Response to Postplant Herbicides
Authors: Norcini Jeffrey G. , Aldrich James H. , Pittman Tim
Published: August 2020

Wiregrass (Aristida beyrichiana Trin. & Rupr.) seedlings were germinated and grown in trays of 96 medium-filled conical tubes. Four-month-old seedlings were treated with Aatrex 4L (atrazine), Factor 65WDG (prodiamine), or Ronstar 50WP (oxadiazon) (applied individually or in combination) in July 1998 and evaluated for phytotoxicity 2, 6, and 10 weeks after application. The experiment was conducted at two sites, one in Chiefland, FL (Florida Division of Forestry, Andrews Nursery), and the other at Monticello, FL (Univ. of Florida/IFAS, North Florida Research and Education Center). Although there was a site by treatment interaction, there was good agreement between sites as to treatments that caused acceptable and unacceptable injury. Ronstar at 2.2 kg ai·ha−1 (2 lb ai·A−1), Aatrex at 2.2 kg ai·ha−1 (2 lb ai·A−1), and Factor at 0.8 or 1.7 kg ai·ha−1 (0.75 or 1.5 lb ai·A−1, resp.) ± Aatrex at 2.2 kg ai·ha−1 (2 lb ai·A−1) caused slight but acceptable foliar injury when applied to 4-month-old (13-cm [5-in] tall) wiregrass seedlings, with either rate of Factor alone causing the least amount of injury. There was an apparent synergistic interaction between Aatrex (either rate) and Ronstar at 4.5 kg ai·ha−1 (4 lb ai·A−1) 2 weeks after application but this effect was no longer consistently apparent by 10 weeks after application. There were no apparent interactions between Aatrex and Factor.
Screening of Predatory Mites as Potential Control Agents of Pest Mites in Landscape Plant Nurseries of the Pacific Northwest
Authors: Pratt P.D. , Croft B.A.
Published: August 2020

To select a biological control agent for suppression of spider mites on landscape plants in western regions of the Pacific Northwest, we compared life history traits of Galendromus occidentalis Nesbitt, Neoseiulus californicus (McGregor) and Neoseiulus fallacis (Garman). We also evaluated abilities of these predatory mites to suppress spider mites in 4 landscape plant species under field conditions. Comparing life history traits from the literature, intrinsic rate of increase was similar between the 2 Neoseiulus species but lower for G. occidentalis. Prey killed per day was greatest for G. occidentalis > N. fallacis > N. californicus. For overwintering abilities, N. fallacis and G. occidentalis are indigenous to the Pacific Northwest and will survive winter assuming overwintering sites are available, but survival of N. californicus is unlikely. Neoseiulus californicus has the widest prey range, G. occidentalis the narrowest, with N. fallacis intermediate. When inoculated into spider mite infested landscape plants, N. fallacis was equally effective at suppressing spider mites as G. occidentalis in either Malus rootstock or Acer shade trees. Further tests with N. fallacis or N. californicus on Spiraea and Rhododendron plants suggested that N. fallacis is equally or more effective at suppressing pest mites, respectively. Compared with the other candidates, N. fallacis was equally effective at controlling pest mites and has a wider prey range than G. occidentalis. Neoseiulus fallacis appears to be the best candidate for biological control of multiple spider mite species on landscape plants in these parts of the Pacific Northwest.
Evaluation of Deciduous Azaleas for Cold Hardiness Potential in the Southeastern United States
Authors: Scheiber S.M. , Robacker Carol D. , Lindstrom Orville M.
Published: August 2020

Twelve taxa of deciduous azalea were evaluated using laboratory procedures to determine hardiness of stems and flower buds. Rhododendron atlanticum, ‘My Mary’, ‘Nacoochee’, and ‘TNLV1’ exhibited the greatest stem cold hardiness, surviving to at least −29C ± 1 (−20F ± 2) in February 1996. Rhododendron oblongifolium exhibited the least stem cold hardiness, surviving to only −11C ± 1 (10F ± 2). All results were consistent with previous field studies. Except for R. viscosum and R. serrulatum, lowest survival temperatures for stems were analogous to reports available in the literature. Rhododendron viscosum and ‘My Mary’ had the lowest survival temperature recorded for flower buds, −23C ± 1 (−9F ± 2), in February 1998 and February 1999, respectively, though not significantly different than most other taxa examined. Lowest survival temperatures for flower buds varied from published accounts, with buds in the present study being less hardy than previously reported. Differences from published reports in the lowest survival temperatures of stems and flower buds are attributed to provenance, temperature fluctuations, cultural effects on the plants, and differences among freeze test protocols.
Cultivar Specific Effects of Mycorrhizal Fungi on the Rooting of Miniature Rose Cuttings
Authors: Scagel C.F.
Published: August 2020

The benefits from root colonization by mycorrhizal fungi are thought to be highest when colonization occurs as early as possible during plant growth. We assessed whether addition of VA mycorrhizal fungi (VAMF) inoculum into rooting medium during cutting propagation would increase the quantity of rooting and the quality of rooted cuttings for five different cultivars of miniature roses (Rosa spp.). Four weeks after cuttings were stuck, the number of cuttings with roots for two cultivars that normally take longer to root, increased with addition of VAMF inoculum into the rooting medium. The combination of hormone treatment (IBA and NAA) and VAMF inoculum in the rooting medium increased the number of rooted cuttings and the number of roots per cutting for three cultivars when compared to cuttings that only received hormone treatment. Increases in root initiation and root growth of cuttings rooted in medium containing VAMF inoculum were not always associated with increased levels of root colonization by VAM fungi. Our results indicate that although adding VAMF inoculum into the rooting medium does not always increase root initiation, in some cultivars the combination of VAMF inoculum and rooting hormones can increase root initiation and potentially increase the quality of rooted cutting produced.
BA Does Not Reduce Detrimental Effects of High Nighttime Temperature on Offset Formation in Hosta
Authors: Schultz Heather C. , Keever Gary J. , Raymond Kessler J. , Dute Roland R.
Published: August 2020

A study was conducted to investigate the effects of nighttime temperatures on offset formation in hosta, and determine if benzyladenine (BA) can overcome potential detrimental effects of high temperatures. Stock plants of two cultivars, ‘Francee’ and ‘Frances Williams’, were divided, potted, and allowed to establish. When roots had reached the substrate-container side interface, half the plants of each cultivar received a foliar spray application of 3000 ppm BA. Plants were immediately transferred to growth chambers programmed for a 12-hour photoperiod at 32C (90F) and a 12-hour dark temperature of 12.8C (55F), 18.3C (65F), 23.9C (75F), or 29.4C (85F). Plants grown at the three lower nighttime temperatures produced more offsets than plants grown at the highest nighttime temperature, but only when treated with BA (both cultivars) or in ‘Francee’ (±BA). Plants treated with BA formed more offsets than −BA plants and ‘Francee’ produced more offsets than ‘Frances Williams’, but only at the three lower nighttime temperatures. Across nighttime temperatures, both cultivars produced more offsets when treated with BA, and ‘Francee’ produced more offsets than ‘Frances Williams’, but only in the presence of BA. Whole plant growth index decreased as nighttime temperature increased, and generally was lower for ‘Frances Williams’ than for ‘Francee’. Plant quality or stage of offset development was not affected by nighttime temperature
Seasonal Irrigation Water Use Efficiency of Multi-Pot Box System
Authors: Irmak Suat , Haman Dorota Z. , Yeager Thomas H. , Larsen Claudia
Published: August 2020

A Multi-Pot Box System (MPBS) was tested during three growing seasons (Fall 1996, Fall 1997, and Fall 1998) for efficient use of irrigation and rainfall in container-grown landscape plant production. This system was compared to a conventional (control) system consisting of black containers spaced on 30 cm (1 ft) centers. Results showed that the MPBS was successful in improving efficient use of irrigation and rainfall for Viburnum odoratissimum, Ker-Gawl. (sweet viburnum). Significant portions of the total rainfall were captured during the Fall 1996 (71.3%) and Fall 1997 (54%) seasons and later supplied to plants increasing rainfall effectiveness and irrigation water use efficiency. Thus, the need for the irrigation applications was significantly reduced for the plants grown in the MPBS. The seasonal irrigation water use efficiency (IWUE) was significantly higher for the MPBS compared to the control system in all seasons, demonstrating that significantly less irrigation water was necessary to produce the same amount or greater plant dry mass (shoot and root). Growth indices [(average width + height) / 2)] and shoot and root dry weights were usually significantly higher in all seasons (with exception of the shoot dry weight in Fall 1997) for the plants grown in the MPBS. Results indicate a potential opportunity for using the MPBS for efficient irrigation and water savings for container-grown landscape plants
Influence of Plant Growth Regulators on Suppression and Quality of ‘Meyer’ Zoysiagrass
Authors: Ervin Erik H. , Ok Changho
Published: August 2020

Proxy and EXP310309D suppressed zoysiagrass at various rates for 4 to 6 weeks during 1999 and 2000. Maximum suppression with Proxy at 3.4 kg ai/ha (3.0 lb ai/A) was 30 to 40% at 3 to 4 weeks after the initial treatment and 32% at 3 and 4 weeks after the second application both years. Maximum suppression at the same time for EXP310309D at 2.7 kg ai/ha (2.4 lb ai/A) was about 45% following the initial treatment and 39% following the second treatment. The suppression was similar when the PGR was applied at the highest (5.3 kg ai/ha) rate. The suppression with Primo at 0.1 kg ai/ha (0.09 lb ai/A) was not as good as EXP310309D in 1999, but the response was similar in 2000. In general, Proxy and Primo did not reduce turf visual quality or color, while both rates of EXP310309D reduced quality and color by 21 to 25% at 2 to 3 weeks after treatment. These data suggest that Proxy and Primo are safe and effective PGRs for use on ‘Meyer’ zoysiagrass maintained as a fairway.
Verification and Establishment of Hydrangea macrophylla ‘Kardinal’ x H. paniculata ‘Brussels Lace’ Interspecific Hybrids
Authors: Reed S. M. , Riedel G. L. , Pooler M. R.
Published: August 2020

An interspecific hydrangea breeding project with the goal of producing cold-hardy hydrangeas with brightly colored flowers was initiated in 1997. The objective of the current study was to transfer Hydrangea macrophylla x H. paniculata plants obtained using ovule culture to in vivo conditions and to verify their hybrid nature. Putative hybrids, representing five H. macrophylla x H. paniculata cultivar combinations, were propagated and rooted in vitro. ‘Kardinal’ x ‘Brussels Lace’ putative hybrids were the only plants that produced roots and survived transfer to the greenhouse. RAPD markers were used to verify hybridity in 13 of these plants, only 5 of which survived. Four of the ‘Kardinal’ x ‘Brussels Lace’ hybrids were greatly reduced in size and slow-growing, having an average height of only 6.4 cm (2.5 in) 8 months after being removed from in vitro conditions. Height, internode length, leaf length and leaf width were approximately six times greater in the remaining ‘Kardinal’ x ‘Brussels Lace’ hybrid than in the four small hybrids. All hybrids resembled H. paniculata in leaf shape and pubescence, and appeared to be less susceptible than H. macrophylla to powdery mildew. Intercrosses between hybrids and backcrosses to parental species will be made when the hybrids flower.
Screening of Cercis (Redbud) Taxa for Ability to Root From Cuttings
Authors: Pooler Margaret R. , Dix Ruth L.
Published: August 2020

The redbud (Cercis species) is a popular landscape small tree or shrub that is valued commercially for its early spring bloom and adaptability to a variety of environmental conditions. Despite its value to the nursery and landscape industies, large-scale production ofredbud has been limited, due in part to the difficulty of propagating clonal (cultivar) material. We screened 11 Cercis taxa for the ability of stem cuttings to regenerate adventitious roots using four growth regulator treatments: Dyna-Gro K-L-N, Woods Rooting Compound, Hormo-Root 2, and KIBA. Overall, C. chingii, C. glabra, and C. yunnanensis had the highest percentage of cuttings that produced roots. The Hormo-Root 2 treatment resulted in the highest rooting percentage over all taxa combined. C. chingii produced the most roots, while C. gigantea, C. siliquastrum, and C. yunnanensis produced the longest roots. Selected clones from this study will be used in our established Cercis breeding program to broaden the genetic base of cultivated Cercis and to produce redbuds with superior ornamental and disease resistance traits that are easier to propagate.
Growth and Flowering Response of ‘May Night’ Salvia and ‘Butterfly Blue’ Scabiosa to Growth Retardants
Authors: Banko T.J. , Stefani M.A. , Dills M.S.
Published: August 2020

In a 1999 experiment, Salvia x sylvestris ‘May Night’ and Scabiosa columbaria ‘Butterfly Blue’ were treated with the following plant growth retardants (PGRs) or PGR mixes: B-Nine (daminozide) at 5000 ppm (applied twice); B-Nine at 5000 ppm + Cycocel (chlormequat chloride) at 1500 ppm; Florel (ethephon) at 500 ppm (applied twice); B-Nine at 5000 ppm + Florel at 500 ppm; Sumagic (uniconazole) at 20 ppm; or B-Nine at 5000 ppm + Sumagic at 10 ppm. B-Nine effectively suppressed growth of salvia but not scabiosa, while Florel was effective on both salvia and scabiosa. However, Florel delayed flowering of both species by about 10 days. Sumagic at 20 ppm suppressed growth of scabiosa but not salvia. The PGR combination treatments, in general, were no more effective, and frequently less effective than the more effective PGR for a given species applied alone. In 2000 Florel was applied once to both salvia and scabiosa at 0, 250, 500, 750, and 1000 ppm. B-Nine (5000 ppm) was also applied to salvia, and Sumagic (20 ppm) was applied to scabiosa. Plant height of salvia was suppressed linearly with increasing Florel concentrations up to 42 days after treatment (DAT). Salvia also responded with a linear increase in inflorescence numbers at 32 and 42 DAT. Florel suppressed the height of scabiosa ‘Butterfly Blue’ linearly up to 52 DAT without affecting the initial number of inflorescences. When the first set of inflorescences was removed and a second set developed, there was a linear increase in inflorescence numbers with increasing concentrations of Florel.
Impact of Application Rate, Treatment Interval, and Placement on the Control of Phytophthora Shoot Blight on Annual Vinca with Azoxystrobin
Authors: Hagan A. K. , Akridge J. R. , Rivas-Davila M. E.
Published: August 2020

Drenches and directed sprays of two rates of azoxystrobin (Heritage 50W) were evaluated at 2- and 4-week intervals for the preventative control of Phytophthora shoot blight (Phytophthora parasitica) in a simulated landscape planting of annual vinca (Catharanthus roseus). ‘Tropicana Rose’ and ‘Pacifica Punch’ annual vinca were planted in May 1998 and April 1999, respectively, adjacent to beds known to be heavily infested with the causal fungus P. parasitica. Regardless of application rate and fungicide placement, the survival rate of plants was often higher when treated with azoxystrobin on a 2-week rather than on a 4-week schedule. Fungicide placement appeared to have little impact on the efficacy of azoxystrobin for the control of Phytophthora shoot blight. In 1998, survival rates of 85 and 90% for ‘Tropicana Rose’ were obtained with directed sprays of 0.35 (9.6 oz/100 gal) and 0.7 gm a.i./liter (19.2 oz/100 gal), respectively, of azoxystrobin applied on a 2-wk schedule as compared with a 10% survival rate for the unsprayed control. Overall, directed sprays of 0.7 gm a.i./liter (19.2 oz/100 gal) of azoxystrobin applied at 2-week intervals gave the best protection from Phytophthora shoot blight. Among the azoxystrobin drench treatments, 10.7 gm a.i./100 m2 (0.7 oz/1000 ft2) applied at 2-week intervals had the highest survival rate in both years.
Effects of Extended Photoperiod and Light Quality on Growth of Carpinus caroliniana, Fagus grandifolia and Gymnocladus dioicus Seedlings
Authors: Richardson-Calfee L.E. , Day J.W. , Witte W.T. , Fare D.C.
Published: August 2020

Although Carpinus caroliniana (American hornbeam), Fagus grandifolia (American beech), and Gymnocladus dioicus (Kentucky coffeetree) have considerable landscape merit, they are not readily available in nurseries. Little research has been conducted on the cultural preferences of these species during nursery production. This study tested the effects of light quality and extended photoperiod on these species. Container-grown seedlings were subjected to three light treatments: 18-hour photoperiod using high pressure sodium lights (HPS), 18-hour photoperiod using incandescent lights (INC), and natural light and daylength (NAT). After 14 weeks, stem height of F. grandifolia seedlings was greatest for HPS light and least for NAT light. After 8 and 12 weeks, light source had no impact on stem heights of C. caroliniana. In 1997, stem height and caliper of G. dioicus were greatest using HPS light. In a repeat of the G. dioicus, experiment in 1998, HPS and INC light treatments resulted in greater stem height, caliper, and shoot and root dry weight compared to NAT treatment. The increase in height of seedlings under the HPS and INC treatments compared to the NAT treatments resulted from a greater number of seedlings that produced a second flush of growth under the HPS and INC treatments.
Protecting Container-Grown Crops from Black Vine Weevil Larvae with Bifenthrin
Authors: Cowles Richard S.
Published: August 2020

Preplant incorporation of Talstar 0.2G (bifenthrin) can prevent root weevil and white grub infestations in container-grown nursery crops. Under some conditions, control failed in greenhouse experiments with black vine weevils. A low-density potting medium with 10 ppm of bifenthrin allowed 14–66% as many black vine weevil larvae to develop on Astilbe, Heuchera, Sedum, Taxus, and Thuja root systems as in an untreated medium. The greatest larval survival was in Sedum, which supported rapid development of larvae as internal feeders. A preplanting dip of roots into an 800 ppm bifenthrin suspension was itself very effective (91–99% control of larvae), and provided additive benefit with preplant potting mix incorporation of Talstar 0.2G. In a comparison of bulk-density based dosing and volume-based dosing of potting media, the best regression model used solely the volume-based dosage for estimating the resulting average larval population, while the weight-based dosage gave a simple relationship for estimating the maximum larval survival. Preventing black vine weevil development requires incorporation of 32 ppm of the granular bifenthrin product into potting media.
A Review of the Federal Clean Water Act and the Maryland Water Quality Improvement Act: The Rationale For Developing a Water And Nutrient Management Planning Process For Container Nursery And Greenhouse Operations
Authors: Lea-Cox John D. , Ross David S.
Published: August 2020

Newly enforced provisions of the Federal Clean Water Act of 1972 and new state laws like the Maryland Water Quality Improvement Act of 1998 are forcing agriculture to develop effective procedures to show that they are not polluting our nation's water resources. Formulating a water and nutrient management process for nursery and greenhouse operations that takes both water and nutrient applications into account is very important. Many operations already have implemented improved management practices to conserve water and nutrients. For those operations that do not have these procedures in place, it will be necessary to find cost-effective ways to ensure that these operations can comply with laws, and document that they can effectively reduce the risk of nutrient movement from their operations to a minimum.
Growth Medium Temperature in Containers as Influenced by Moisture Content
Authors: Keever G.J. , Cobb G.S.
Published: August 2020

In response to changes in ambient air temperature, temperatures within containers of a pine bark growth medium were slower to change and remained at 0°C (32°F) longer, as the moisture content of the medium increased. This suggests that timing of irrigation can reduce temperature extremes of short duration within containers.
Soil Amendments at Planting
Authors: Corley W.L.
Published: August 2020

The growth response of 10 difficult to establish landscape shrubs and trees was evaluated in a series of 4 backfill experiments utilizing hole sizes, organic amendments, mulch, and/or drip irrigation. Growth responses varied among species, but no consistent, positive responses were derived from traditional backfill amendments.
Cultivar Registration, a Joint Effort
Authors: Widmoyer Fred B.
Published: August 2020

This paper recommends cooperation between researchers, public gardens and nurserymen in a project to properly name, release and document new plant releases to the industry. Leadership for registration of woody plants not specifically assigned to any other society has been assigned to the American Association of Botanical Gardens and Arboreta (AABGA). Greater participation may be stimulated by publication of articles on registration in various media; development of interactive programs between nurserymen, public gardens, universities and the Office of Plant Patents; involvement of state representatives interested in stimulating the use of the International Code of Cultivated Plants—1980. Programs are in various stages of implementation.
Effect of Several Controlled-Release Fertilizers on the Growth of Four Foliage Plants
Authors: Sanderson Kenneth C. , Waterhouse Linda G. , Martin W.C. , Patterson Richard M. , Williams John C.
Published: August 2020

Five types of controlled-release fertilizers were evaluated in individual experiments on Dieffenbachia amoena Bull., Philodendron scandens subsp. oxycardium Shott. Bunt. and Ficus benjamina L. Precise 12.0N-2.6P-5.0K (12-6-6) an encapsulated liquid fertilizer, applied at 656 kg (569 lb/A) N per ha per year, produced similar Dieffenbachia and Philodendron plant dry weights as 5 impregnated vermiculite and one ureaformaldehyde applied at higher rates of N. In a comparison with a water soluble 20.0N-8.7P-6.6K (20-20-20) fertilizer on Brassaia actinophylla Endl., dry weights and foliage color ratings of Brassaia plants fertilized with the water soluble fertilizer were greater than those of plants receiving the controlled release fertilizers. Ficus height, visual rating, dry weight and differences in green color values of leaves of plants fertilized with Precise 12.0N-2.6P-5.0K (12-6-6) were greater than those receiving other controlled-release fertilizer treatments. In a second experiment, Ficus plants fertilized with high rates of several controlled-release fertilizers and Scott Pro-Grow 25.0N-2.2P-8.2K (25-10-10) rates were equal or better in growth than plants receiving Precise and Osmocote 14.0N-6.1P-ll.6K (14-14-14). Mag Amp 7.ON-I7.4P-4.1K (7-40-6) plants treated with 900 kg/ha (784 Ib/A) and 1200 kg/ha (1045 lb/A) performed poorly in all growth parameters measured. Plant growth from high rates of controlled-release fertilizers surface applied at the beginning of the experiment was equal to that produced with 20.0N-8.7P-16.6K (20-20-20) soluble fertilizer applied weekly at the rate of 1582 kg N/ha (1477 lb/A) per year.
Effects of Selected Pruning Methods on Subsequent Growth of Photinia × fraseri
Authors: Dirr Michael A.
Published: August 2020

Single-leader, container-grown Photinia × fraseri Dress were selected for height uniformity and left unpruned(UN), pruned to 4 nodes with leaves (4NL), 8 nodes with leaves (8NL), or pruned to 8 nodes with all leaves removed (8N). Visible buds were present following pruning at all nodes. Unpruned (UN) plants produced only 1.9 breaks per plant; 4NL-4.0 breaks; and 8NL-7.1 breaks. The 8N plants developed short lateral breaks, but these died by the fourth week. All plants in the 8N treatment were dead at the termination of the experiment. The UN plants produced 39 cm (15.4 in) of new shoot growth; 4Nl-46 cm (18in), and 8NL-60 cm (23.6 in). Quality of 4NL and 8NL plants was excellent.
Sethoxydim (Poast) and Oxyfluorfen (Goal) Efficacy and Tolerance by Landscape Plants
Authors: Benjamin Coffman C. , Ray Frank J. , Gentner Walter A.
Published: August 2020

Granular Goal (oxyfluorfen) [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(tri-fluoromethyl)benzene] at 4.5 kg/ha (4.0 lb/A) was applied to 8 species of woody landscape plants alone or with a following postemergence application of Poast (sethoxydim) [2-(1-(ethoxyimino)butyl)-5-(2-(ethylthio)propyl)-3-hydroxy-2-cyclohexen-1-one] at 0.6 or 1.1 kg/ha (0.5 or 1.0 lb/A). Sethoxydim was applied with and without crop oil (1%, v/v). These treatments were made one time in 1981 and 1982. Applications of Poast (sethoxydim) at 0.6 kg/ka (0.5 lb/A) with or without crop oil controlled barnyardgrass [Echinochloa crusgalli (L.) Beauv.], giant foxtail (Setaria faberi Herrm.), and large crabgrass [Digitaria sanguinalis (L.) Scop.]. Goal (oxyfluorfen) alone at 4.5 kg/ha (4.0 lb/A) reduced the rate of estasblishment of the perennial broadleaf weeds Canada thistle [Cirsium arvense (L.) Cyrillo] and white heath aster (Aster pilosus Willd.). Up to 86% reduction in total weed cover was obtained when Goal (oxyfluorfen) application was followed by Poast (sethoxydim). Crop quality was not affected by any herbicide treatments.
Wound Compartmentalization in Cultivars of Acer, Gleditsia, and Other Genera
Authors: Santamour Frank S.
Published: August 2020

Results of studies on a broad range of plant material (20 cultivars in 7 genera) suggest that most, if not all, landscape tree culttvars that have been successfully commercially propagated by budding or grafting are strong wound compartmentalizers. All of the cultivars tested with chisel wounds on mature trees or young plants exhibited strong wound compartmentalization that prevented wood discoloration from occurring in tissue internal to the wound zone. These included red maple cultivars ‘Armstrong,’ ‘Autumn Flame,’ ‘Bowhall,’ ‘Gerling,’ ‘October Glory,’ ‘Red Sunset,’ ‘Scarlet Sentinel,’ ‘Tilford,’ ‘V.J. Drake,’ and ‘Wageri’; Norway maple ‘Emerald Queen’; silver maple ‘Silver Queen’; honeylocust ‘Majestic,’ ‘Skyline,’ and ‘Sunburst’; ginkgo ‘Pendula’; Callery pear ‘Bradford’; green ash ‘Marshall Seedless’; American linden ‘Nova’; and ‘Regent’ scholartree.