bluuebunny/crossref_metadata_2025 huggingface dataset:
Ectomycorrhizal Effect on Host Plant Response to Drought Stress
Authors: Mudge Kenneth W. , Diebolt Kent S. , Whitlow Thomas H.
Published: August 2020

Ectomycorrhizal symbiosis affects the water relations and drought resistance of woody landscape trees and shrubs in the families Pinaceae, Fagaceae, Betulaceae, and others. It has frequently been observed that host plants mycorrhizal with drought-adapted fungi exhibit improved growth and survival during drought and more rapid recovery after rewatering than non-mycorrhizal plants or plants mycorrhizal with fungi not adapted to dry sites. Relatively few studies have addressed the effect of mycorrhizae on the physiological response of host plants to drought stress. It is suggested that some fungi confer drought tolerance to their host, while others confer drought avoidance. Possible mechanisms by which mycorrhizae influence host water relations are discussed.
Graft Compatibility in Woody Plants: An Expanded Perspective
Authors: Santamour Frank S.
Published: August 2020

Four thousand years of practice and research in grafting woody plants have not provided significant answers to questions about the causes of graft incompatibility nor allowed valid predictions to be made regarding potential incompatibilities between individual plants of most species of landscape trees. In this paper, the author briefly reviews some of the more recent research findings dealing with graft success and failure and discusses three areas of research that have heretofore not been adequately studied. These are (a) wound compartmentalization, (b) girdling, and (c) lignification.
Graft Incompatibility Related to Cambial Peroxidase Isozymes in Chinese Chestnut
Authors: Santamour Frank S.
Published: August 2020

Chinese chestnut (Castanea mollissima Blume) seedlings were ring-grafted with bark rings from seedlings of the same species whose cambial peroxidase isozyme banding pattern was similar to or different from that of the stock. When the isozyme phenotype of the donor matched that of the stock plant, a complete encircling cambium was formed and vascular xylem continuity was restored through the zone of grafted tissue. However, when the isozyme phenotype of the donor differed from that of the stock, vascular continuity was not restored. In some cases, the cambial cells of the donor plant died after producing a few new cells. When the donor cambium continued to function as a meristem, only parenchymatous cells were produced. Peroxidases are the only enzymes known that mediate the polymerization of cinnamic alcohols into lignin and the bonding of lignin to carbohydrates of the primary cell wall. These findings substantiate the hypothesis that plants differing in major peroxidases would not be graft compatible.
A Dibble Fertilizer Applicator for Containers in Nursery Beds
Authors: Parish R.L. , Chaney P.P. , Meadows W.A. , Fuller D.L.
Published: August 2020

A machine to punch dibble holes in multiple filled containers and simultaneously to meter fertilizer has been designed, built and tested. The machine handles up to 12 containers at a time in beds 6 containers wide. Transported and powered by a tractor, this machine straddles the containers in a nursery bed. Alignment of the mechanism over the containers and the dibble operation itself are accomplished hydraulically. Force and speed of the dibbles are adjustable. Uniformity of metering is good, with coefficients of variation in the range of 2 to 30%.
Comparison of Rootability of Stem Cuttings from Seedlings of Aesculus sp. and Mature Aesculus × arnoldiana ‘Autumn Splendor’
Authors: Bergmann B.A. , Hackett W.P. , Pellett H.
Published: August 2020

Rootability was evaluated for stem cuttings taken at varying positions and developmental stages from seedlings of Aesculus and from the mature trees of Aesculus × arnoldiana ‘Autumn Splendor’. Rooting was 100% for cuttings taken from 2-week-old seedlings and 0% for those obtained from the crown of the mature tree 2 months after commencement of spring growth flush. Intermediate rootability was found for cuttings taken from 1-month-old seedlings and from the 2 week-old growth of suckers at the base of the mature tree. Rooting of cuttings with intermediate rooting potential was increased by a quick dip treatment with 2500 ppm indole-3-butyric acid (IBA) or by using apical rather than basal stem segments. Commercially acceptable rooting was not achieved using cuttings from root suckers or the crown of Aesculus ‘Augumn Splendor’.
Pruning Responses of Tissue-Cultured Plantlets of Rhododendrons
Authors: Lohr Virginia I. , Sudkamp Andrew B.
Published: August 2020

Plantlets of Rhododendron ‘Molly Ann’, R. ‘Paprika Spiced’, and R. ‘Travis L.’, recently rooted from tissue culture, were grown in a greenhouse in individual containers. Plants pruned by pinching, top-pruning, or root-pruning were compared to unpruned plants. Growth, as measured by shoot height, shoot dry weight, root dry weight, and stem caliper, was generally reduced by pruning. Top-pruning and pinching induced branching in all cultivars tested and improved stem taper (ratio of basal to upper caliper) in two cultivars, including R ‘Travis L.’, which is particularly prone to develop weak stems when produced by tissue culture.
Pretransplant Application of Goal (Oxyfluorfen) for Weed Control in Container-grown Nursery Crops
Authors: Derr Jeffrey F.
Published: August 2020

No injury was observed to ‘Hershey Red’, ‘Pleasant White’ and ‘Scarlet Rose’ azalea (Rhododendron obtusum Planch.) ‘Prince of Wales’ juniper (Juniperus horizontalis Moench), ‘Helleri’ holly (Ilex crenata Thunb.) or ‘Green beauty’ boxwood (Buxus microphylla Siebold & Zucc.) following pretransplant applications of Goal (oxyfluorfen) at rates ranging from 0.6 to 4.5 kg ai/ha (0.5 to 4.0 lb/A). Acceptable control of common groundsel (Senecio vulgaris L.) (less than one weed per pot) lasted approximately 1 month at 0.6 kg/ha (0.5 lb/A), 2 to 3 months at 1.1 kg/ha (1.0 lb/A), 3 to 4 months at 2.2 kg/ha (2.0 lb/A) and 4 months at 4.5 kg/ha (4.0 lb/A) with sprayed applications of Goal. Sprayed applications of Goal at 1.1 kg/ha (1.0 lb/A) gave equivalent weed control to a post-transplant application of Ornamental Herbicide 2, a granular formulation containing 2% oxyfluorfen and 1% pendimethalin, at 3.3 kg ai/ha (3.0 lb ai/A).
Cambial Peroxidase Enzymes Related to Graft Incompatibility in Red Maple
Authors: Santamour Frank S.
Published: August 2020

Two major anodal peroxidase isozyme bands occurred with high frequency (70–80%) in the cambial tissue of red maple (Acer rubrum L.) stems and roots. Some red maples, and all silver maples (A. saccarinum L.) tested lacked the lower enzyme band. The presence or absence of the lower enzyme band was not related to the geographic origin of the plants. Because of varying degrees of polyploidy in red maples and hybrids between red and silver maples, the staining intensity of the enzyme bands, especially the lower band, varied considerably. Still, bark-ring grafts between 2-banded and 1-banded red maples exhibited incompatibility symptoms similar to other tree combinations with dissimilar cambial peroxidase isozymes. During the extended time period of 3 to 5 years required for complete envelopment of the severed stock stub in budded red maples, zones of poorly lignified cells are formed at the boundary between incompatible stock and scion cambia. After the increased growth of the scion has developed a large crown, various stresses such as wind and freezing temperatures may combine to fracture the graft union along the zone of unlignified cells. Isozyme patterns are given for many red maple cultivars, and most have both A and B bands; some data are provided on isozyme inheritance. Nurserymen may significantly reduce problems of graft compatibility in these cultivars by collecting seed for seedling rootstock production only from parent trees with AB enzyme phenotypes or, for any cultivar, by creating seed orchards that will provide seedlings of the desired enzyme properties.
Response of Two Florist Azalea Cultivars to Foliar Applications of a Growth Regulator
Authors: Keever Gary J. , Foster William J.
Published: August 2020

Bonzi (paclobutrazol) sprays of 100 and 150 ppm controlled bypass shoot development and increased flower number of ‘Alaska’ azalea compared to the control, while minimally affecting forcing time and bloom size. Sprays of 150 and 200 ppm suppressed bypass shoot development and increased flower number of ‘Prize’ azalea compared to the control without affecting bloom size. Paclobutrazol was more effective than B-Nine (daminozide) in suppressing bypass shoot development and enhancing flowering. Forcing time decreased and bloom size increased for paclobutrazol-treated plants of both cultivars compared to daminozide-treated plants.
Evaluation of Nursery Container Designs for Minimization or Prevention of Root Circling
Authors: Appleton Bonnie L.
Published: August 2020

Six different container designs were evaluated for their effectiveness in minimizing or preventing the development of circling roots around the sides and/or bottoms of containers. While both shrub and tree species were tested, the roots of the shrubs were generally small and fibrous enough that selection of a container to minimize or prevent circling roots was not an important consideration. For the tree species, the greatest amount of circling reduction was achieved with the soft polybags and the rigid stepped-pyramid containers. Because considerable difference exists in the cost of the newly-designed containers, both cost and root-modifying effectiveness should be considered if root modification is deemed important.
Influence of Root-zone Temperature on Growth of Ailanthus altissima (Mill.) Swingle
Authors: Graves William R. , Dana Michael N. , Joly Robert J.
Published: August 2020

Growth of tree-of-heaven (Ailanthus altissima (Mill.) Swingle) seedlings was evaluated during a 28-day exposure to constant root-zone temperatures of 18°, 24°, 30°, and 36°C (64°,75°, 86°, and 97°F). Leaf area, stem length, root-to-shoot ratio, and shoot and root dry weights were greatest among plants with 24°C (75°F) root zones. Diminished growth among plants at high root-zone temperatures was associated with reduced leaf conductance. After 14 days of treatment, leaf diffusive resistance of plants in the 36°C (97°F) regime was eight times greater than that of plants with 24°C (75°F) root zones. Regulation of leaf gas exchange among plants with 36°C (97°F) root zones probably contributed to the maintenance of moderate leaf water potentials but limited the fixation of carbon necessary to sustain growth.
Postplant Application of Nitrogen Fertilizer to Pinus sylvestris at Different Stages of Establishment
Authors: Hensley David L. , Gray Aldridge E.
Published: August 2020

Ammonium nitrate and urea formaldehyde at 56, 112, and 224 kg N/ha (50, 100, and 200 lb N/A) were surface-applied to Scotch pine (Pinus sylvestris) planted the same spring and 1 and 2 years previously. Survival and growth were measured and compared with untreated controls during the following two seasons. Survival of plants established the same year as treatment was significantly greater at the lowest fertilizer rate, regardless of material. Second season height growth of trees receiving 56 kg N/ha (50 lb/A) in the year of planting was significantly greater than those receiving 224 kg N/ha (200 lb/A). There were no significant growth responses by trees established for 1 or 2 years prior to treatment. Stem diameter and number of lateral buds at the apex were not affected by any of the treatments.
Water Use and Average Growth Index of Five Species of Container Grown Woody Landscape Plants
Authors: Knox Gary W.
Published: August 2020

Liners of Juniperus horizontalis Moench ‘Wiltonii’, Ilex crenata Thunb. ‘Rotundifolia’, Rhododendron × L. ‘Hershey's Red’, Pyracantha × M.J. Roem ‘Teton’, and Photinia × fraseri Dress were grown to saleable size in 3.1 1 (1 gal) containers. Plant water consumption was measured during 336 days from June 24, 1986, to June 19, 1987. Pyracantha consumed the most water (50.4 1 (13.3 gal)/plant) while photinia consumed the least water (37.8 1 (10.0 gal)/plant). Based on the increase in growth index per liter of water consumed, photinia used water most efficiently. Growth index, pan evaporation, or growth index and pan evaporation were the best predictors of plant water use.
Medium Temperature Influences the Rooting Response of Hibiscus rosa-sinensis L.
Authors: Carpenter William J.
Published: August 2020

Adventitious rooting of stem cuttings of Hibiscus rosa-sinensis L. ‘Pink Versicolor’, ‘Brilliant Red’, ‘Jim Hendry’ and ‘Silver Anniversary’ was evaluated after propagation at medium temperatures of 18°, 22°, 26°, 30° and 34°C (65°,72°,79°,86° and 93°F). Cuttings of all cultivars propagated at medium temperatures of 26° and 30°C rooted faster and developed more roots with larger fresh and dry weights. Rooting percentages for each cultivar was similar among all propagation medium temperatures, but 26° and 30°C (79° and 86°F) reduced the weeks required for rooting 50% of the cuttings and periods in weeks between 10% and 90% rooting. The most vigorous rooting ‘Pink Versicolor’ had more uniform root emergence and the best response at unfavorable medium temperatures, while the poorest ‘Silver Anniversary’ had inconsistent root formation at all temperatures.
Influence of Metolachlor on Ilex crenata Thunb. for Control of Yellow Nutsedge
Authors: Beste C. Edward , Frank J. Ray
Published: August 2020

A single spring or fall application of Dual 8E (metolachlor) at 13.5 kg/ha (12.0 lb/A) to newly planted ‘Hetzii’ and ‘Howardi’ Japanese holly caused 15 to 18% injury during the first few weeks after treatment. No additional injury or reduced growth was evident with any Dual treatments 4 weeks after application. Applications of Dual at rates up to 13.5 kg/ha (12.0 lb/A) to established ‘Hetzii’ holly did not cause injury or affect plant height × width. Dual at 4.5 kg/ha (4.0 lb/A) to 13.5 kg/ha (12.0 lb/A) was adequate to control yellow nutsedge (Cyperus esculentus L.).
Preemergent Weed Control in Container and Field Grown Woody Nursery Crops with Gallery
Authors: Neal Joseph C. , Senesac Andrew F.
Published: August 2020

Two container and four field tests were conducted to evaluate Gallery (isoxaben) for preemergent weed control in container and field grown woody nursery crops. Gallery was applied to newly potted nursery crops at 0.56 and 1.1 kg ai/ha (0.5 and 1 lb ai/A) alone and in combination with Surflan (oryzalin) or Treflan (trifluralin). No injury was observed on container grown Coral ‘azalea Bells,’ Rhododendron ‘Roseum Elegans,’ rockspray cotoneaster, forsythia, potentilla ‘Tangerine,’ Japanese dwarf garden juniper, ‘Old Gold’ juniper, or plaintain lily ‘Albo-marginata.’ Gallery, applied alone, caused no injury to field grown sawara false cypress, honey locust, Japanese yew, California privet, ‘San Jose’ holly, white pine, Douglas fir, white fir, green ash, or Japanese rose. Gallery injured field grown common lilac. When combined with Surflan, temporary reduction in white fir and Japanese barberry quality resulted. Douglas fir was injured significantly by Surflan, alone or in combination with Gallery. Gallery provided excellent control of many broadleaf weeds including pigweed, common groundsel, and dandelion, but poor control of annual grasses such as crabgrass, goosegrass, and fall panicum. The combination of Gallery plus Surflan provided an expanded spectrum of weed control with excellent safety on most container and field grown woody nursery crops.
Summer Annual and Winter Annual Weed Control in Field Soil and Soilless Media with Gallery (lsoxaben)
Authors: Neal Joseph C. , Senesac Andrew F.
Published: August 2020

Field and container experiments were conducted to evaluate Gallery (isoxaben) efficacy on several common nursery and landscape weeds. Gallery was applied at rates from 0.14 to 1.1 kg ai/ha (0.125 and 1 lb ai/A). Annual grass control with Gallery generally was poor at application rates below 0.84 kg/ha (0.75 lb/A). Higher rates were needed for consistent foxtail and annual bluegrass control. Gallery controlled most broadleaf weeds at ≤0.56 kg/ha (0.5 lb/A) in field soil and a soilless potting medium. The exception was velvetleaf, which was not controlled with 1.1 kg/ha (1 lb/A). Combining Gallery with Surflan (Snapshot) at 1.1 + 3.4 kg/ha (1 + 3 lb/A) provided excellent control of all weeds tested. Equivalent weed control was obtained with a tank mix of Gallery plus Surflan at 0.28 + 3.4 kg/ha (0.25 + 3 lb/A) in 1989, suggesting that when used in combination with Surflan the rate of Gallery may be reduced relative to the comparable Snapshot rate, without sacrificing weed control.
Influence of Winter Protection Covers on Survival and Hardiness of Container Grown Ilex crenata Thunb. ‘Green Island’ and Euonymus fortunei (Turcz.) ‘Emerald 'n Gold’
Authors: Regan Richard P. , Ticknor Robert L. , Hemphill Delbert D. , Chen Tony H.H. , Murakami Paul , Fuchigami Leslie H.
Published: August 2020

Five systems for protection of container grown nursery stock were compared for freeze injury to shoots and roots of Ilex crenata Thunb. ‘Green Island’ and Euonymus fortunei (Turcz.) ‘Emerald 'n Gold’. In three treatments, plants were protected starting November 15, 1988 either in a white co-polymer house or with structureless non-woven polypropylene covers (N-Sulate™ or Typar™). In a fourth treatment, structureless clear polyethylene was applied when temperatures were cold enough (−7°C (25°F) to cause injury. The controls were not covered. The white co-polymer house and the temporary covering with clear polyethylene reduced the number of hours below −7°C (25°F) in the canopy or medium and resulted in fewer plant losses compared to the nonwoven covers or the controls. Development of shoot and root hardiness of both species was monitored prior to and after the low temperature period. Roots of plants under long-term protective covers were slightly less hardy than those not covered.
Micropropagation of White Flowering Eastern Redbud (Cercis canadensis var. alba L.)
Authors: Yusnita S. , Geneve R. L. , Kester S. T.
Published: August 2020

A white flowering Eastern redbud (Cercis canadensis var. alba L.) has been successfully micropropagated. Two node explants collected from the initial flush of spring growth were cultured on woody plant medium (WPM). Increased shoot multiplication occurred at 10,15 and 20 μM (2.3, 3.4 and 4.5 ppm) benzyladenine (BA). Microshoots were rooted in vitro on half strength WPM with a 15-day treatment of 100 and 300 μM (18.6 and 55.9 ppm) α-naphthaleneacetic acid (NAA) or 100 and 300 μM (20.3 and 60.9 ppm) indolebutyric acid (IBA) prior to being moved to full strength WPM without growth regulators. Percentage rooting and the mean number of roots per cutting were comparable between NAA and IBA treated microcuttings, however, the subsequent root morphology differed between the two treatments. NAA treated plants developed a coarse, unbranched root system, while IBA treated cuttings developed a more desireable fine, branched root system. Rooted microshoots were successfully acclimated to greenhouse conditions.
Effect of Pruning on the Growth Inhibiting Activity of Sumagic (Uniconazole)
Authors: Norcini Jeffrey G. , Knox Gary W.
Published: August 2020

Pruning date was investigated as a possible factor influencing the inhibitory activity of Sumagic (uniconazole) on growth of 6 container grown woody landscape plants. Plants were pruned 1 or 10 days before uniconazole was applied as a foliar spray or medium drench on June 22, 1988. Plant height and width were recorded weekly through November 30, 1988. Pruning date influenced the pattern of growth and/or the final size of plants treated with foliar-applied uniconazole. It also influenced uniconazole's inhibitory activity the first 2 to 3 weeks after application. Uniconazole was most effective on Pyracantha and Ligustrum lucidum the first 2 to 3 weeks after treatment if applied 1 day after pruning. Drench applications resulted in greater growth inhibition than foliar sprays; however, drench treatments caused unacceptable reduction in plant size.
Desiccation Tolerance in Bare-rooted Apple Trees Prior to Transplanting
Authors: Chen Tony H.H. , Murakami Paul , Lombard Porter , Fuchigami Leslie H.
Published: August 2020

Ten types of apple (Malus domestica L.) trees (six different scions on M.7 rootstock and four ‘Red Delicious’ scions on M.7, MM. 111, MM.106 and seedling rootstocks) were subjected to air drying for periods of 0 to 48 hr with or without 3 months of cold storage at 0°C (32°F). The kinetics of water loss during drying treatment and the transplanting survival and regrowth vigor were recorded. Both the scions and rootstocks influenced the tolerance of apple trees to desiccation stress. Among the plant materials tested, ‘Red Delicious’ on MM. 111 rootstock had the highest level of tolerance to desiccation. Three months of cold storage at 0°C (32°F) resulted in the considerable loss of tissue water, but the grafted trees survived if no further desiccation occurred prior to planting. Only ‘Red Delicious’/MM. 111 tolerated desiccation from the combination of three months of cold storage followed by a 48 hr exposure to air drying, while other scion/rootstock compound systems seldom survived. The analyses of water loss from apple trees indicated that the loss did not follow a simple first order reaction. However, there were two distinct first order water loss slopes suggesting that the loss was from two fractions of water inside plant tissues. One fraction of tissue lost water at a faster rate than the following second fraction which was slowly released from the plant tissues. There was no difference in the critical water content and rate of water loss between the tolerant trees, (i.e., ‘Red Delicious’ on MM. 111) and the others. Therefore it is suggested that trees on MM. 111 are more tolerant to desiccation because of the tolerance to water loss in the tissue.
Seed Germination of Intermountain Penstemons as Influenced by Stratification and GA3 Treatments
Authors: Kitchen Stanley G. , Meyer Susan E.
Published: August 2020

Propagation of the genus Penstemon for use in landscape horticulture has been handicapped by a lack of understanding of seed dormancy and a practical method for breaking dormancy for numerous species. The extent of dormancy in seeds of 27 wild populations of Penstemon representing 16 Intermountain species was investigated by subjecting seeds to stratification (moist prechilling) of 2 to 16 weeks at 2°C (36°F) and varying concentrations of gibberellic acid (GA3). Germination varied from 0 to 88% for non-treated seeds and from 13 to 100% for seeds treated with 250 ppm GA3. Collections from 10 species required 12 or more weeks of stratification for complete germination. Three species exhibited reduced germination after stratification when compared to the non-chilled control. Gibberellic acid significantly reduced the stratification requirement of seeds for the more dormant species. Concentrations of 150, 250, and 500 ppm GA3 were equally effective in breaking dormancy for most species. The considerable variability in seed dormancy suggests that the most practical solution to penstemon propagation from seed may be the selection of species and ecotypes with minimal dormancy.
Economic Feasibility of a Shade Tree Container Production System
Authors: Chinery D.H. , Rhodus T. , Struve D.K.
Published: August 2020

An economic model was developed to estimate the feasibility of producing red oak (Quercus rubra) whips in an established container nursery. Cost per plant was compared for a simulated container nursery of 6.88 and 13.76 ha (17 and 34 acres) at different levels of production. Variable cost per plant ranged from $3.48 when producing 100 plants to $3.16 when producing 4,160 or more. Fixed cost per plant was $.42 to $.55 higher in the small nursery, depending upon level of production. Total cost per plant varied from $3.86 to $4.59, depending upon nursery size and level of production. Sensitivity analysis indicated that total cost per plant is less responsive to changes in wage rate than changes in interest rates on operating capital. Reducing losses during the rapidgrowth and overwintering phases of production is necessary in order to minimize total cost per plant.
Anomalous Root Structure on Woody Plants in vitro
Authors: Smith M.A.L. , McClelland M.T. , Timmermann R.
Published: August 2020

The anatomical structure of in vitro-generated roots contrasted sharply with ex vitro roots produced on parallel treatments of micropropagated woody plant clones. In vitro roots contained enlarged, irregular, frequently pigmented cortical cells with numerous intercellular spaces, and only primary vascular system 4–5 weeks after initiation, while ex vitro roots of the same age were comprised of smaller, uniformly arranged cell layers and were developmentally further advanced (exhibited secondary vascular system development). Light exposure was not a major influence on anomalous structure of in vitro roots, other than pigmented cell frequency. Ex vitro rooting hormone stimulated production of thicker, more frequent root initials, although root structure beyond the point of emergence from the stem quickly transformed to the slender, compact character typical of ex vitro production.
Soil Temperature and Copper Application Rate Affect Growth and Copper Deficiency of Aglaonema commutatum ‘Fransher’
Authors: Conover C.A. , Poole R.T. , Satterthwaite L.N.
Published: August 2020

Fransher aglaonema (Aglaonema commutatum Schott. ‘Fransher’) were used during the winter and spring in two duplicate 4 × 3 factorial randomized block design experiments with four continuous soil temperatures [13.0, 18.5, 24.0 and 29.5° ± 1°C (55, 65, 75, and 85°F ± 1.8°F)] and three copper levels [0, 0.05, and 0.1 g/15 cm pot (0, 0.0017 and 0.0035 oz/6 in pot(] from Cu Sequestrene. Plants were placed into zoned forced-air systems for soil temperature control in a glass greenhouse with an average maximum light intensity of 13 klx (1200 ft-c) and minimum and maximum air temperatures of 16 and 30°C (60 and 86°F), resp. Plant grade, color grade, number of breaks, root fresh weights, and elemental tissue content of Ca, Mg, and Cu increased linearly with increased soil temperature, while elemental tissue content of K decreased linearly with increased soil temperature. As copper application rate increased, plant grade, color grade, and elemental tissue content of Cu increased linearly and elemental tissue content of K, Ca, Mg, Mn, and B decreased linearly. Interactions of increased soil temperature and Cu application rate resulted in increased top fresh weights, elimination of Cu deficiency symptoms, and decreased leaf elemental P content.
Effects of K-IBA Rates and Timing on Rooting Percentage and Root Quality of Amelanchier laevis
Authors: Still Steven M. , Zanon Scott
Published: August 2020

Semi-hardwood cuttings of Amelanchier laevis Weig. were taken on May 24, June 15, and July 26 and treated with five different rates of K-IBA: 2,500, 5,000, 10,000, 15,000, and 25,000 ppm. Rooting percentage and root quality were highest in cuttings taken in Mayor June. Root quality was significantly higher when cuttings were treated with higher rates of IBA.
Influence of Entomophagous Nematodes and Irrigation on Black Vine Weevil in Euonymus fortunei (Turcz.) Hard. Mazz. Beds
Authors: Owen Nancy P. , Raupp Michael J. , Sadof Clifford S. , Bull Brenda C.
Published: August 2020

Entomophagous nematodes were applied to beds of Euonymus fortunei (Turcz.) Hard. Mazz. in an urban park to evaluate their potential for controlling black vine weevil, Otiorhynchus sulcatus (Fabricius). Although no significant difference was attributed to nematode treatments, weevil damage in non-irrigated beds was lower than in irrigated beds. Irrigation management may be helpful for controlling this pest.
Cold Hardiness of Magnolia grandiflora L. Cultivars
Authors: Lindstrom Orville M. , Dirr Michael A.
Published: August 2020

Established cultivars of Magnolia grandiflora L. with observed cold hardiness limits and recently introduced cultivars with unknown cold hardiness limits were subjected to laboratory cold hardiness evaluation. The laboratory cold hardiness data corresponded closely to the observed field performance of ‘Edith Bogue’, ‘Little Gem’, ‘Spring Grove #16’, and ‘Spring Grove #19’. ‘Edith Bogue’ is considered the most cold hardy cultivar under landscape conditions. It also proved the most cold hardy in laboratory tests with leaves and stems hardy to at least − 24°C (−11°F) and −27°C (−17°F) over the three test dates. ‘Little Gem’, the least cold hardy under field conditions, was also the least cold hardy in laboratory tests. The Spring Grove cultivars survived −32°C (−25°F) in 1976 and 1983 and −30°C (−22°F) in 1989 under landscape conditions. Laboratory test data corroborated observed field hardiness.

Three recent introductions, ‘Bracken's Brown Beauty’, ‘Phyllis Barrow’ and ‘Select #3’ showed different laboratory cold hardiness profiles. ‘Bracken's Brown Beauty’ developed the greatest stem cold hardiness followed by ‘Select #3’ and ‘Phyllis Barrow’. ‘Select #3’ and ‘Phyllis Barrow’ exhibited similar leaf cold hardiness, while ‘Bracken's Brown Beauty’ had less hardy leaves. Results indicated that promising clones of Magnolia grandiflora could be laboratory tested for cold hardiness with the resultant data used to predict survivability and geographic adaptability.
Birch Seedling Response to Irrigation Frequency and a Hydrophilic Polymer Amendment in a Container Medium
Authors: Tripepi R.R. , George M.W. , Dumroese R.K. , Wenny D.L.
Published: August 2020

Water-absorbing polymers (hydrogels) are promoted for their potential to increase the water-holding capacity of container media. European birch (Betula pendula Roth) seedlings (1 + 0 plugs) were planted in a container growth medium amended with 0, 1.2, 2.4 or 3.6 kg/m3 (0, 2, 4 or 6 lb/yd3) of Broadleaf P-4, a commercial hydrogel, and watered either daily or once every 3 or 5 days. When hydrogel was incorporated in the growth medium, shoot and root dry weights and leaf area were reduced by 19, 29 and 18%, respectively, compared to controls. Increases in stem height and diameter as well as shoot-root ratio were unaffected by hydrogel amendment rate. Compared to seedlings in polymer-amended media, plants growing in medium without hydrogel had significantly lower stomatal conductance and transpiration on fewer than 25% of the measurement dates. Irrigation frequency significantly affected all plant growth indices and stomatal parameters; seedlings irrigated daily grew the most and had the highest stomatal conductance and transpiration. Although polymer-amended media held more water than medium without hydrogel at all measured tensions, this moisture was retained in the expanded gel rather than being available for plant uptake at higher tensions. The hydrogel appeared to have little benefit for container production of birch.
Effect of Time and Application of Sodium Chloride in the Dormant Season on Selected Tree Seedlings
Authors: Headley David B. , Bassuk Nina
Published: August 2020

Seedlings of Acer platanoides, A. rubrum, Quercus palustris, and Q. rubra were subjected to soil-applied sodium chloride (NaCl) solutions of 0.0, 1.1, and 5.0 N NaCl once every month beginning in October and ending in April. In May, the trees were evaluated for damage, harvested and dried. Growth measurements and shoot Na and Cl content were analyzed. For all four species, plants in the November through February/March salt treatments sustained little plant damage and reduction in growth. The October application of NaCl resulted in heavy plant damage and reduced growth in each species, while April NaCl applications produced similar results in A. rubrum and Q. palustris alone. Shoot Na and Cl content were greater in plants in the October, March, and April salt treatments.

In a second experiment, actively-growing, greenhouse-grown plants of the four species were subjected to either a fertilizer solution plus 0.25 N NaCl at every irrigation or a single application of 1.1 N NaCl followed by normal irrigation thereafter. A. platanoides lost its resistance to soil-applied NaCl by mid summer, while A. rubrum and Q. palustris were sensitive to a high dosage of NaCl applied at this time and Q. rubra was resistant. In both experiments, there were significant interactions between the time of NaCl application and the periodicity of plant growth, soil temperature, precipitation, and leaching of the salt from the soil as well as genetic factors, which affected the amount the salt injury sustained by trees.
Evaluation of Ten Landscape Trees for the Midwest
Authors: Hensley David L. , Wiest Steven C. , Long Charles E. , Pair John C. , Gibbons Frank D.
Published: August 2020

Specific problems in plant selection for the midwest vary widely because of large differences in climate, soils, and urbanization. A project was started in 1984 to identify and evaluate worthy landscape plants for use in Kansas and other areas of the midwest. As of 1991, 40 species and cultivars have been planted in six locations throughout Kansas. Data collected for four years include survival, height, stem diameter, foliage quality, and overall quality. The results of the first two completed segments of this study (1984 and 1985) are presented.
Results and Future Production and Marketing Estimates Projected from a Survey of Christmas Tree Growers in Georgia
Authors: Lindstrom O.M. , Florkowski W.J. , Moorhead D.J.
Published: August 2020

Virginia pine (Pinus virginiana Mill.) is the most planted Christmas tree in the South and its production has remained stable over the past few years. Leyland cypress [x Cupressocyparis leylandii (A.B. Jacks. and Dallim.) and Dallim. and A.B. Jacks.] is relatively new to the market, but the number of trees harvested has increased dramatically in the past 5 years (over 600%) where as Redcedar (Juniperus virginiana L.) production shows little market growth over the past 5 years. Due to the long lag period from planting to harvest, the data to correlate planting to harvests of White pine (Pinus strobus L.) was limited. Pearson correlation coefficients support the idea that future Christmas tree harvests can be reliably estimated from existing and estimated tree planting data for Virginia pine, White pine, Redcedar and Leyland cypress in the short term. With this information, growers can make better decisions regarding the numbers and species of trees to produce and be able to choose an appropriate marketing approach.
Effects of Growing Media and Aerial Environments on Acclimatization of In Vitro-Grown Miniature Rose Plantlets
Authors: Rogers R.B. , Knight S.L. , Smith M.A.L.
Published: August 2020

Initial acclimatization of in vitro-rooted plantlets of miniature rose (Rosa chinensis var. minima ‘Red Ace’) in high humidity and continuous light (most similar to the in vitro environment) increased plant growth (33% greater root area and 34% greater shoot area) relative to plants acclimatized under intermittent mist during early ex vitro growth stages, but later transfer to standard greenhouse conditions caused a temporary lag in continued growth. Direct transfer from in vitro culture conditions to a greenhouse mist bench inhibited growth during acclimatization, but permitted more rapid growth rate (28 and 30% more shoot and root area, respectively) during transition to the greenhouse growing environment. Direct transplant of in vitro rooted microcuttings to a growing medium containing soil resulted in high survival rate and circumvented the need for an interim potting medium, whereas transplant to Jiffy-9 pellets resulted in the highest plant losses.
Growth Regulators and Pruning Alter Growth and Axillary Shoot Development of Dianthus
Authors: Foley James T. , Keever Gary J.
Published: August 2020

Annual carnation, Dianthus caryophyllus L., and garden pink, Dianthus chinensis L., were treated with foliar sprays of Bonzi (paclobutrazol), Cycocel (chlormequat chloride), or Pro-Shear (BA), and/or pruned to suppress shoot elongation or promote axillary shoot development. Bonzi (paclobutrazol) at 100 or 200 ppm was effective in suppressing shoot elongation of annual carnation over a 14-week period and garden pink over an 8-week period without increasing days to flower of either species. The combination of pruning and Bonzi (paclobutrazol) inhibited shoot elongation of both species compared to pruning alone. Flowering of both species was delayed 11 to 14 days compared to the control when pruning was combined with Bonzi (paclobutrazol). Cycocel (chlormequat chloride) suppressed shoot elongation of annual carnation but was not as effective as Bonzi (paclobutrazol); shoot elongation of garden pink was only suppressed for 2 weeks after Cycocel (chlormequat chloride) application. Application of ProShear (BA) at 100 or 200 ppm did not promote axillary shoot development of either species nor did Pro-Shear (BA) combined with pruning. Pruning of annual carnation and garden pink suppressed shoot elongation through week 7 and week 4, respectively, compared to the control. Pruning of annual carnation increased axillary shoot development compared to all other treatments, while pruning of garden pink decreased flower and primary axillary shoot numbers. Pruning delayed flowering in both species about 12 days compared to the control.
Factors Affecting Growth of Ophiostoma ulmi on Elm Callus Tissue
Authors: Domir Subhash C. , Schreiber Lawrence R. , Ichida Jann M.
Published: August 2020

We examined growth of the Dutch elm disease fungus, Ophiostoma ulmi, on callus derived from a susceptible American elm (Ulmus amencana, selection A), an American elm of intermediate resistance (U. americana, selection 8630), and a resistant Siberian elm (Ulmus pumlia) at 16, 22, and 28°C (61,72, and 83°F) and inoculation concentrations of 15 × 106, 2 × 106, or 0.3 × 106 conidia/ml. After 72 hours, the rates of fungal growth for all treatments were most rapid on calli from the American 8630 selection followed by the American A and Sibenan selections. While fungal growth was more rapid over American 8630, it was more dense on American A. Most rapid fungal growth occurred at 22°C (72°F) and was directly proportional to the inoculum concentration. A significant interaction was noted between callus source and temperature.
Gibberellin A3 Treatment of Seeds, Container Volume, Substrate pH, and Nitrogen Source and Rate Influence Growth of Containerized Seabeach Amaranth (Amaranthus pumilus)
Authors: Norden Daniel S. , Warren Stuart L. , Blazich Frank A. , Nash David L.
Published: August 2020

Seeds of seabeach amaranth (Amaranthus pumilus Raf.), a species federally listed as ‘threatened,’ were stratified (moist-chilled) for 90 days at 4C (39F) or treated with a solution of the potassium (K) salt (K-salt) of gibberellin A3 (K-GA3) at 1000 mg·liter−1 (ppm) for 24 hr. After treatment, both groups of seeds were sown in containers of two volumes, 139 or 635 cm3 (9 or 39 in3) with a substrate of peat:pine bark (1:1, v/v) amended with one of two rates of pulverized dolomitic lime [2.24 or 4.48 kg·m−3 (3.8 or 7.6 lb·yd−3)]. Containers were maintained in a greenhouse. After seedling emergence, seedlings were fertilized with a 20N-4.4P-16.6K (20N-10P205-20K20) acidic, water soluble fertilizer or a 15N-2.2P-12.5K (15N-5P205-15K20) basic, water soluble fertilizer applied thrice weekly at nitrogen (N) application rates (NARs) of 75, 150, 225, or 300 mg·liter−1. The study was terminated 8 weeks after seeds were sown and data recorded. Regardless of fertilizer, acidic or basic, top dry weight and leaf area of seabeach amaranth increased linearly with increasing NAR. Maximum top dry weight and leaf area occurred with N at 300 mg·liter−1, whereas root dry weight was unaffected by NAR. Both fertilizers increased electrical conductivity (EC) linearly with increasing NAR, and EC values of 1.15 to 1.18 dS·m−1 were adequate for maximum top growth or leaf area. Substrate pH decreased linearly with increasing NAR 21, 43, and 57 days after initiation. Top and root dry weights and leaf area were greatest for seedlings derived from seeds treated with K-GA3. Large containers yielded top and root dry weights and leaf area 61, 33, and 57% greater, respectively, than smaller containers. Top N concentration increased linearly with increasing NAR for acidic and basic fertilizers with N concentrations of 58.4 and 50.4 mg·g−1, respectively, at maximum top dry weight. Although top nutrient content of N increased linearly with NAR, top N content was unaffected by either rate of lime or type of fertilizer.
Vegetative Propagation of American Elm (Ulmus Americana) Varieties from Softwood Cuttings
Authors: Oakes Allison D. , Kazcmar Nicholas A. , Maynard Charles A. , Powell William A.
Published: August 2020

Softwood cuttings of American elm varieties ‘Jefferson’, ‘New Harmony’, ‘Princeton’, ‘R18-2’, ‘Valley Forge’, and a tissue-cultured non-transformed control clone (BP-NT) were rooted using three different treatments to determine which method would be most suitable for small-scale propagation. The treatments included aeroponic chambers, an intermittent-mist bench in a greenhouse, and Grodan rootplugs soaked in a nutrient solution. The rootplug treatment had the highest percentage of rooted shoots (44%) followed by the intermittent-mist bench treatment (20%) and lastly by the aeroponics chambers (10%). The rooted cuttings from the rootplug treatment also looked substantially healthier and had more fresh growth four weeks after potting than the other two treatments. The Grodan rootplug treatment is recommended, but additional testing can be useful to improve the overall rooting percentage.
Fate of Preemergence Herbicide Applications Sprayed Through Containerized Hydrangea Canopies
Authors: Derksen R.C. , Altland J.E. , Rennecker J.C.
Published: August 2020

Preemergent herbicides are applied to the soil or potted-substrate surface to prevent weed seedling establishment. Spraying through a canopy above the soil surface represents a challenge because of the filtering effect of the canopy on the spray stream and because of the additional distance created between the soil surface and nozzle. The objective of this work was to determine the effect spray quality, spray volume, and air delivery had on delivery of sprays to the substrate surface through a potted hydrangea canopy. Petri dishes and water sensitive paper were placed on the substrate surface of potted hydrangeas (H. paniculata ‘DVPpinky’) to collect spray material falling through the canopy. Eight targets were used for each plant and were place around the circumference of the pot in the four cardinal directions. Different sizes of TeeJet flat fan extended range (XR) and air induction (AI) nozzles were selected to provide 187 and 374 liters·ha−1 (20 and 40 gal·A−1) application rates with medium (XR) and very coarse (AI) droplet spectrums. A specially designed, five-port, air-assist delivery device was used to make air-assisted delivery applications using TeeJet XR8001 flat fan tips. Treatments were applied over the top of a 3 × 5 pot arrangement of potted plants at a speed of 4.0 km·h−1 (2.5 mph). No irrigation was applied either before or after treatment applications. Foliage sampled from the top of the hydrangea canopy had 8–10 times higher spray deposits than foliage from the middle elevation and the targets on the substrate surface. Surface coverage under the canopy ranged from 2–10% and average spot density ranged from 17–41% spots·cm−2 on water sensitive paper targets. Overall, the AI11003 used to make very coarse spray applications at 374 liters·ha−1 (40 gal·A−1) produced the highest mean spray deposits and coverage on the soil surface. The air-assist sprayer produced the highest deposits in the canopy but the lowest deposits and coverage on the substrate surface. On average, only about 5% of the spray actually reached the intended target (substrate surface) across all treatments and approximately 50–60% of the spray material was accounted for on the foliage. Larger droplet sizes and higher spray volumes will help ensure better delivery through the canopy.
Tree-Based Mulches and their Leachate Suppress Weed Seed Emergence
Authors: Maggard Adam O. , Will Rodney E. , Hennessey Thomas C. , Cole Janet C.
Published: August 2020

The objectives of this research were to compare the effects of eastern redcedar (bark and wood), hardwood (bark and wood), pine bark nugget (bark), pine (bark and wood), eucalyptus (bark and wood), cypress (bark and wood), and red-dyed (bark and wood) mulches on emergence of large crabgrass, johnsongrass, common lambsquarter, and redroot pigweed and to determine the possible chemical effects of these mulches by treating seeds with mulch leachate before and after planting. In the first experiment, seeds were planted in pots and one of each mulch type was applied directly above seeds. In the second study the seeds were pre-soaked and watered with mulch leachate. Although interactions between mulch type and weed species occurred, mulch reduced weed emergence by an average of 79% compared to non-mulched pots with eucalyptus having the least effect of the mulches (average 50% reduction). Leachate treatments had less of an effect than mulch, but reduced weed emergence by 16% averaged across all treatments. Red-dyed mulch leachate lowered weed emergence by 41%, more than all other mulch leachate, while eastern redcedar leachate reduced emergence by 23%. Overall, the wood mulch treatments had beneficial effects of reduced weed emergence compared to not using mulch and the response was dominated by physical rather than chemical influences.
Propagation Container Type, Time in Container, and Root Pruning Affect Root Development of Young Acer rubrum
Authors: Gilman Edward F. , Paz Maria , Meador Dustin , Fisher Paul
Published: August 2020

Numerous propagation containers have been developed in an effort to reduce root deformities on tree and shrub nursery stock. Root attributes in containers are also impacted by retention time in the container. A popular shade tree, Acer rubrum L., was grown in 6 different propagation containers for two time periods and root pruned or not before shifting to 10 liter (3 gal) black plastic containers to evaluate root system quality. Root pruning when shifting into larger 10 liter (3 gal) containers resulted in more structural roots, adventitious roots from cuts, and woody second-order roots, growing closer to the substrate surface due to a reduced angle of departure from the trunk. Root pruning improved root system quality by increasing the number of straight, radially-oriented roots growing from all propagation containers except for Ellepots placed in contact with other Ellepots which had an equivalent high number of straight roots without pruning. By many measures, all propagation container types produced nearly equivalent root systems provided root balls were mechanically pruned by shaving off roots on the periphery when shifting to 10 liter (3 gal) containers. However, root pruning when shifting had no effect on mortality or trunk diameter growth in 10 liter (3 gal) containers. Without root pruning, the propagation container type and retention time had a large influence on root morphology in 10 liter (3 gal) containers.
Use of Ground Wheat Straw in Container Nursery Substrates to Overwinter Daylily Divisions2
Authors: Locke James C. , Altland James E.
Published: August 2020

Wheat (Triticum sp.) straw is being evaluated as a potential component in soilless container mixes either alone or combined with compost to replace a significant portion of the substrate currently supplied by pine bark and peat moss. The objective of this study was to evaluate wheat straw and horse manure compost, locally available resources, as components of container media for establishing and overwintering daylily (Hemerocallis fulva ‘Stella D'Oro’). A standard commercial, sphagnum peat-based substrate was amended with either wheat straw, horse manure compost, or a combination of the two. Stella D'Oro daylily divisions were grown in each substrate mix and overwintered in an unheated structure for eight months. Physical properties of the mixes were determined to be within production standards and media shrinkage was minimal. Daylilies in all substrate combinations were of comparable vigor to the non-amended substrate when growth resumed in the spring.