bluuebunny/crossref_metadata_2025 huggingface dataset:
Tree Seedling Root Architecture Alteration by Tap Root Pruning1
Authors: Hankin Shanon , Lo Marvin , Balestri Frank , Watson Gary
Published: August 2020

Nursery production of strong taprooted woody plants typically includes pruning to interrupt taproot development. To discern the impact this practice could have on seedling root architecture, we quantified changes to root architecture after taproot pruning and restriction separately in Catalpa (Catalpa speciosa) and Kentucky coffee tree (Gymnocladus dioicus). Taproot pruning resulted in a large and significant increase in the number of new, vertically oriented roots from the cut end of the primary root (regenerated taproots) in both species. Catalpa seedlings, which produced many strong laterals on unpruned taproots, showed greater reduction in lateral root number and size after taproot pruning than Kentucky coffee tree (with fewer and smaller natural lateral roots). The two species responded differently to restriction of the single, unpruned taproot by container depth (15, 30, 60 cm). For catalpa, with more shallow laterals naturally, the number of laterals was not significantly changed by restriction of the taproot by air pruning at any container depth, but lateral diameter was reduced by the 15 cm-deep container and biomass was reduced by the 30 cm-deep container, compared to the 60 cm-deep container. For Kentucky coffee tree with fewer natural laterals, restricting the taproot at 15 cm significantly increased the number and diameter of lateral roots compared to the 30 and 60 cm-deep containers, suggesting that restricting the taproot could increase the number of laterals in species that naturally produce fewer. Restricting multiple taproots on root-pruned plants generally did not affect lateral root development for either species, but this may have been due to the low number of lateral roots on those root systems.

Index words: root architecture, nursery production, urban soils

Species used in this study: Catalpa [Catalpa speciosa (Warder) Warder ex Engelm. ]; Kentucky coffee tree [Gymnocladus dioicus (L.) K. Koch]
Timing of Collection and Preparation of Hardwood Stem Cuttings for Propagating Hybrid Hazelnuts 1
Authors: Braun Lois , Wyse Donald
Published: August 2020

In previous trials we had found that dormant hybrid hazelnuts crown suckers collected in the fall after leaf drop can be successfully rooted if they are chilled at least until January before being placed in low-cost humidity tents in a greenhouse. The first objective of this experiment was to determine if cuttings could be rooted if started earlier, so as to avoid the heat stress found in the greenhouse in late spring and early summer. The second objective was to see if rooting rates could be improved by collecting non-dormant crown suckers in September and October, before leaf drop. We hypothesized that by collecting stems at a time in the fall when woody plants are translocating resources from leaves to their root systems, we could direct those resources towards growth of adventitious roots. This hypothesis proved to be wrong: stems collected in full leaf died, even with measures to avoid moisture loss from leaves. However, we found that stems collected soon after leaf abscission, in early November, could be rooted if placed in the humidity tents in late November, after only three weeks of artificial chilling at 2 C (36 F). That is much less chilling than we previously thought was needed.

Index words: propagation, Corylus americana (Walter), Corylus avellana (L.), rooting, chilling requirement.

Chemicals used in this study: indole-3-butyric acid (IBA).

Species used in this study: hybrid hazelnuts [Corylus americana (Walter) x Corylus avellana (L.)].
Evaluation of Rosa Species Accessions for Resistance to Eriophyid Mites1
Authors: Solo K. M. , Collins S. B. , Schneider L. G. , Hajimorad M. R. , Hale F. A. , Wilkerson J. B. , Windham A. S. , Byrne D. H. , Windham M. T.
Published: August 2020

Rose rosette disease, caused by rose rosette virus (RRV), is an epidemic affecting nearly every rose cultivar in the United States. The only hosts for Phyllocoptes fructiphilus, the eriophyid mite that vectors RRV, are Rosa species. Eighteen Rosa species were evaluated for mite resistance by collecting foliage samples from July to November in 2016 and 2017, from which mites were extracted. Mites were isolated through a series of sieves and counted using a stereomicroscope. The response variable was expressed as the number of mites per gram of optimal rose tissue. Mite data were evaluated to determine the peak week for mite populations for each year. The mite populations varied by rose species (α = 0.05) in 2016 but not 2017. Due to high variability in mite counts, the species were not as clearly distinguishable as expected. This high variability is likely due to factors such as differential growth rates of the roses, weather, presence of RRV in the rose, and the quality of the tissue collected throughout the season. Experimental design revisions are proposed for future studies looking at Rosa species resistance to eriophyid mite populations.

Index words: rose rosette virus, rose rosette disease, Phyllocoptes fructiphilus Keifer, virus, vector.

Species used in this study: Phyllocoptes fructiphilus (Keifer), Prairie Rose [Rosa arkansana (Porter), Forest Farm]; Carolina Rose [Rosa carolina (L.), Forest Farm]; Rosa clinophylla (Thory), Rogue Valley Rose; White Prairie Rose [Rosa foliolosa (Nutt.), Rogue Valley Rose]; White Prairie Rose [Rosa foliolosa (Nutt.) Antique Rose Emporium]; Father Hugo Rose [Rosa hugonis, Rogue Valley Rose]; Musk Rose [Rosa moschata (J. Herrm.), Antique Rose Emporium]; Multiflora Rose [Rosa multiflora (Thunb.)]; Shining Rose [Rosa nitida (Willd.), Rogue Valley Rose]; Shining Rose [Rosa nitida (Willd.), Antique Rose Emporium]; Nootka Rose [Rosa nutkana (C. Presl.), Rogue Valley Rose]; Tea Rose [Rosa odorata (Andrews), Foundation Plant Services, Davis, CA]; Swamp Rose [Rosa palustris (Marshall), Antique Rose Emporium]; Swamp Rose [Rosa palustris (Marshall), Ever Blooming Antique Rose Emporium]; Chestnut Rose [Rosa roxburghii (Tratt.), Antique Rose Emporium]; ‘Plena' Chestnut Rose [Rosa roxburghii (Tratt.), Rogue Valley Rose]; Rugosa Rose [Rosa rugosa (Thunb.), Bailey's Nursery]; ‘Alba' Rugosa Rose [Rosa rugosa (Thunb.), Bailey's Nursery]; Climbing Prairie Rose [Rosa setigera (Michx.), Antique Rose Emporium]; Rosa soulieana (Crép.), Ralph Moore; Virginia Rose [Rosa virginiana (Mill.), Forest Farm]; Porterfolia Memorial Rose [Rosa wichuraiana (Crép.), Antique Rose Emporium]; Mountain Woods' Rose [Rosa woodsii (Lindl.), Rogue Valley Rose].
Sulfur Amendment of Soil Improves Establishment and Growth of Firs in a Field Naturally Infested with Phytophthora1
Authors: Cowles Richard S.
Published: August 2020

Acidification of soil from pH 6 to 4 by incorporating elemental sulfur reduced mortality and improved color and initial growth of Fraser fir, Abies fraseri (Pursh) Poir., and Canaan fir, Abies balsamea (L.) Mill. var. phanerolepis Fernald, planted into a field that had previously experienced significant losses consistent with phytophthora root rot. Acidifying the soil improved tree color starting the year of planting and persisting through five years. During their second year after planting, extension of terminal growth was 12.5 vs. 5.6 cm (4.9 vs. 2.2 in) for plots with soil pH of 4 and 6, respectively, averaged across tree species. In subsequent years, the growth rate of trees was unaffected by having acidified the soil. Over the course of five years, the average annual mortality rate for the trees was 1.4, 4.0, 9.7, and 12.2% for Canaan fir (pH 4), Canaan fir (pH 6), Fraser fir (pH 4), and Fraser fir (pH 6), respectively. However, all tree mortality for Canaan fir planted into acidified soil occurred during the first two years. A root dip with potassium phosphite at the time of planting only benefitted Fraser fir. Minimizing losses of trees in this field would require planting species less susceptible or resistant to phytophthora root rot infection and soil acidification.

Index words: soil acidification, phytophthora root rot, potassium phosphite, root dip

Species used in this study: Fraser fir; Abies fraseri (Pursh) Poir.; Canaan fir; Abies balsamea (L.) Mill. var. phanerolepis Fernald

Chemicals used in this study: acibenzolar-S-methyl (Actigard 50WDG); clothianidin (Arena 50WDG); imidacloprid (Xytect 2F); potassium phosphite (Helena Prophyt); sulfur
Rooting Efficiency of Amur Maple Seedless Selections Produced by Mutagenesis1
Authors: Noyszewski Andrzej K. , Smith Alan G.
Published: August 2020

Amur maple (Acer ginnala Maxim.) is a widely planted small tree with attractive red fall foliage. In many states, it is classified as a noxious weed and regulations restrict propagation and sale, limiting customer choice. Stem cuttings are commonly used as a means of asexual propagation of Amur maple, with softwood cuttings being the easiest to root. Here we report adventitious rooting efficiency of seedless Amur maple selections using four indole-3-butyric acid (IBA; 500, 1,500, 5,000, 10,000 ppm) and four naphthalene acetic acid (NAA; 100, 500, 1,500, 5,000 ppm) treatments and a no hormone control. Overall, cuttings treated with 5,000 or 10,000 ppm IBA and 5,000 ppm NAA resulted in the highest percent rooting (PR), mean number of roots (MNR), and mean length of the longest root (MRL) across all seedless selections. Seedless selections SW-30-14 and SW-30-130 had the highest PR, 66% and 67%, respectively, and will perform well in commercial propagation. This level of rooting was greater than that of the cultivar ‘Bailey Compact' that had 46% PR, and the seedless selection SW-30-159 that had the lowest PR (10.3%), MNR (0.3), and MRL (0.2 in) averaged across all treatments. Cuttings from 4 of the 5 seedless selections treated with 1,500 ppm NAA had the greatest PR, whereas ‘Bailey Compact' and SW-30-159 had the greatest PR with 5,000 ppm NAA. Results indicate that rooting efficiency was impacted by mutagenesis in some selections, which may require optimization of propagation methods for those selections.

Index words: adventitious rooting, auxin, vegetative propagation, sterile, non-native invasive.

Species used in this study: Amur maple (Acer ginnala Maxim.).

Chemicals used in this study: indole-3-butyric acid (IBA; 500, 1,500, 5,000, 10,000 ppm) and naphthalene acetic acid (NAA; 100 500, 1,500 5,000 ppm).
Influence of Root Pruning and Fertilizer on Survival and Quality of Two Bare-Root Rose Cultivars
Authors: Whitcomb Carl E.
Published: August 2020

Bareroot, field-grown ‘Mon-Cheri’ and ‘Olympiad’ roses were planted in containers with light or heavy root pruning and 6 fertilizer treatments. Heavy root pruning resulted in a 43% loss of ‘Mon-Cheri’, but only 2% losses of ‘Olympiad’ roses. The medium rate of 4.8 kg/m3 (8.15 yd3) of Osmocote 18N-26P-9.8K (18-6-12) increased survival, growth and appearance in containers. Following transplanting into the landscape, both slow-release N, P, K fertilizer and a micronutrient fertilizer increased floral counts for both cultivars.
Influence of Photoperiod on Winter Growth of Seven Species of Tropical Landscape Trees
Authors: Broschat Timothy K. , Donselman Henry
Published: August 2020

Dalbergia sissoo Roxb. ex DC. (sissoo), Psidium littorale Raddi. (cattley guava), Lysiloma bahamensis Benth. (false tamarind), Callistemon rigidus R.Br. (bottlebrush), Calophyllum inophyllum L. (mastwood), Bucida buceras L. (black olive), and Koelreuteria elegans (Seem.) A.C. Sm. (golden rain tree) seedlings were grown under long day (LD) and natural daylength (ND) photoperiods from September 7, 1982 to April 7, 1983 to determine if LD would prevent quiescence and thereby allow year round growth and reduced production time. Koelreuteria and Dalbergia under ND essentially ceased growth during these months, but plants grown under LD continued to grow at a rapid rate during this time. Psidium, Calophyllum, Callistemon, and Lysiloma grew at equivalent rates throughout the winter under both photoperiods, but in Bucida growth under ND was greater than under LD during this time.
Effect of Fall Temperature and Lighting on Growth of Rhododendron Rooted Cuttings
Authors: Kasperek Laurie Menzel , Havis John R.
Published: August 2020

Summer-rooted rhododendron cuttings were forced into growth using natural photoperiod, incandescent or red light (660nm) as a night break between 2200 and 0100 hours at both 17°C (63°F) and 10°C (50°F) minimum night temperature (MNT) for 3 weeks beginning September 28, 1982. Longer shoots were produced on Rhododendron ‘PJM hybrids’ under incandescent light than under red light or natural photoperiod. Rhododendron ‘Roseum Elegans’ produced longer shoots under both light regimes than under natural photoperiod and longer shoots at 17°C (63°F) MNT than at 10°C (50°F) MNT. Neither temperature nor light treatments significantly increased the average number of breaks per plant of either cultivar. Spring growth of Rhododendron ‘Roseum Elegans’ was delayed by both red and incandescent fall light treatments, but not by the high temperature fall treatment.
Effect of Slow Release Fertilizers on Formation of Mycorrhizae and Growth of Container Grown Pine Seedlings
Authors: Crowley David E. , Maronek Dale M. , Hendrix James W.
Published: August 2020

Slow-release fertilizer formulations at various NPK analyses, release rates, and application rates were evaluated for their effects on seedling growth and mycorrhizal development of container-grown seedlings of Pinus echinata (Mill.) inoculated with Pisolithus tinctorius (Pers.) Coker and Couch. Fertilizer release rate and application rate affected formation of mycorrhizae. At 9.0 kg/m3 (15.0 lb/yd3), greater numbers of seedlings formed mycorrhizae and a greater portion of the root system was mycorrhizal with the 8 to 9 month release fertilizer, regardless of formulation, than with the 1 to 2 or 3 to 4 month release fertilizers. Best seedling growth and mycorrhizae formation was obtained with the 21N-3.OP-11.6K (21-7-14) 8 to 9 month release fertilizer at the 4.5 kg/m3 (7.5 lb/yd3) application rate. Because fertilizer release is temperature dependent, deleterious effects of over fertilization may be greater with higher greenhouse temperatures. The low benefits of fertilization rates higher than 4.5 kg/m3 (7.5 lb/yd3) do not warrant the risk of interference with formation of mycorrhizae.
Long-term Survival of American Elms Injected with Carbendazim Salts for Dutch Elm Disease Control
Authors: Gregory Garold F.
Published: August 2020

Therapeutic and prophylactic fungicide injection as a Dutch elm disease (DED) control measure prevented the loss of many valuable elms during this study in Greenfield Village historic park at Dearborn, Michigan. The survival of treated elms was monitored following injection of the fungicide, Lignasan BLP® (methyl 2-benzimidazole carbamate salt), and removal of DED symptomatic limbs. After 5 years following therapeutic injection, all injected DED elms averaged 25 percent survival, whereas those that were injected when they had 10 percent or less of DED foliar symptoms averaged 33 percent survival.
Influence of Sulfur on Soil pH and Growth of Cenizo [Leucophyllum frutescens (Berl.) I.M. Johnst]
Authors: Hipp Billy W. , Simpson Benny J.
Published: August 2020

Studies were conducted on two soils at Texas Agricultural Experiment Station (TAES) at Dallas to determine the influence of sulfur (S) application on soil pH and subsequent growth of cenizo (Leucophyllum frutescens). Application of 16800 kg/ha (7.5 Tons/A) reduced pH of Houston black clay from 7.6 to about 5.8 and application of 33600 kg/ha (15 T/A) reduced soil pH to 3.7. The same rates of S did not affect pH of Stephen silty clay because of the high CaCO3 found in the Stephen soil. The high S rate reduced growth and/or killed cenizo grown on Houston black clay but did not influence plant growth on Stephen silty clay. These studies indicate that the application of S to typical soils of the Blackland prairie is not necessary for improving growth of cenizo.
Effects of Chemical Defoliation and Bare Root Storage on Carbohydrate Levels and Spring Growth in Euonymus alata
Authors: Boersig Michael R. , Negm Fayek B.
Published: August 2020

For 2 seasons, levels of starch, sucrose and galactitol were measured in roots of Euonymus alata (Thunb.) Sieb, following fall spray treatments with a mixture of endothall [7-oxabicyclo- (2,2,1) heptane-2, 3-dicarboxylic acid] and ethephon (2-chloroethyl phosphonic acid) and overwintering in the field or in a common storage facility. The spray-storage treatment decreased starch levels by 80% and 43% during winter months of the first and second years, respectively. Dry weight of new shoot growth was reduced 66% as a result of the spray-storage treatment during the first year, but there was no reduction of dry weight relative to controls during the second year. During both years, galactitol levels in the roots were not affected by either treatment.
Characterization of Filbert (Corylus) Species and Cultivars Using Gradient Polyacrylamide Gel Electrophoresis
Authors: Ahmad Z. , Daley L.S. , Menendez R.A. , Lagerstedt H.B.
Published: August 2020

A chemical identification procedure previously used to identify apple and pear species, cultivars and clonal accessions, was tried with Corylus (filbert, hazel) species, cultivars and clonal accessions. Following electrophoresis, the peroxidase, phenol oxidase, and acid phosphatase isozyme patterns on anionic polyacrylamide gradient gels were determined. These patterns were found to vary between clonal accessions, but did not change, within a given accession during and following the test period (May through October). Thus, these patterns were considered to represent genetic characteristics suitable for identification purposes. The patterns were used to identify 78 Corylus accessions at the National Clonal Germplasm Repository Corvallis, Oregon. All accessions tested (species, cultivars and clones) were distinguishable using this system. The diversity of isozyme patterns was greater in Corylus than Pyrus populations previously sampled. This technique appears to have the potential to readily identify filbert accessions and could be an important aid in the characterization of germplasm material.
Susceptibility of Calathea Species and Cultivars to Bipolaris setariae
Authors: Chase A.R.
Published: August 2020

Relative susceptibility of five species of Calathea to Bipolaris setariae, the cause of Helminthosporium leaf spot, was tested under greehouse conditions. Calathea louisae ‘Green Feather’ and C. roseopicta were highly resistant, while C. makoyana ‘Peacock Plant’ was moderately resistant. The most susceptible species were C. argentea ‘Silver Portrait’ and ‘Vandenheckei’, and C. insignis ‘Rattlesnake’.
Water Quality and Calcium plus Magnesium Fertilization Effects on Container-Grown Gardenia and Japanese Holly
Authors: Brosh D.L. , Whitcomb C.E. , Akers S.W. , Claypool P.L.
Published: August 2020

Combinations of calcium carbonate with magnesium oxide were found to be superior to dolomite as calcium and magnesium fertilizers for container production of gardenia (Gardenia jasminoides ‘Radicans’) and Japanese holly (Ilex crenata ‘Convexa’). When growth and quality measurements were analyzed, a number of significant water quality by fertilizer interactions were found for both species. In contrast, when responses to water quality and to different rate combinations of calcium carbonate and magnesium oxide (no dolomite) were analyzed, only the visual grade of gardenias showed a significant water quality by fertilizer interaction. Since calcium and magnesium are common constituents of irrigation waters, it is suggested that commercial container nurseries test different rate combinations of calcium carbonate and magnesium oxide for their own water supply and plant species of importance.
Factors Affecting Foliar Absorption of Nutrients by Selected Landscape and Herbaceous Plants
Authors: Reed David Wm. , Tukey Harold B.
Published: August 2020

Plants and solution properties affecting the absorption of double-labeled 86Rb 33P-phosphate, pH 7.2, by chrysanthemum leaves were studied. Leaf age did not affect absorption greatly. Optimum concentration for maximum total absorption and efficiency of absorption of both Rb and P without leaf burn was 20-30 mM Rb phosphate. Urea and several structurally related compounds (acetamide, propionamide and Rb acetate) decreased Rb and P absorption due to formation of salt deposits. Of 18 commercially available surfactants tested at 0.1%, only one significantly increased P absorption and all significantly decreased Rb absorption; many were phytotoxic. Of a variety of 20 different herbaceous ornamental and woody landscape species tested for their efficiency of absorption, P absorption ranged from 0.2-39% and Rb absorption ranged from 0.2-42%; surfactants generally increased the absorption of P and Rb for those species with waxy, pubescent or otherwise hard-to-wet leaves.
Weed Management with Fluazifop (Fusilade), Haloxyfop (Verdict), Sethoxydim (Poast) and Oxyfluorfen (Goal) in Groundcovers and Woody Landscape Plants
Authors: Benjamin Coffman C. , Ray Frank J.
Published: August 2020

Annual preemergence applications of granular Goal (oxyfluorfen) [2-chloro-l-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene] at 4.5 kg/ha (4.0 lb/A) were applied on several kinds of woody landscape plants alone or with a subsequent postemergence treatment of either Fusilade (fluazifop) [( ± )-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid], Verdict (haloxyfop) [2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy] propanoic acid] or Poast (sethoxydim) [2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one] at 0.3 kg/ha (0.25 lb/A) or 0.6 kg/ha (0.5 lb/A). The postemergence treatments were also applied without previous applications of Goal. The investigation was conducted at Beltsville, Maryland, from 1983 through 1985. Application of Goal (oxyflurofen) alone reduced the yearly growth of broadleaf and grass weeds, however, over-time horseweed (Conyza canadensis (L.) Cronq.) and white heath aster (Aster pilosus Willd.) increased their contribution to the weed cover. Annual grass weeds including fall panicum (Panicum dichotomiflorum Michx.), large crabgrass (Digitaria sanguinalis (L.) Scop.), giant foxtail (Seteria faberi Herrm.), and stinkgrass (Eragrostis cilianensis (All.) E. Mosher) were significantly reduced by applications of Fusilade, Verdict, and Poast. Weed cover reductions up to 60% resulted from treatments by Goal followed by anyone of the three grass herbicides. Hinocrimson azalea was injured by applications of Fusilade at 0.3 kg/ha (0.25 lb/A) and Verdict at 0.6 kg/ha (0.5 lb/A).
Clear and White Plastics for Freeze Protection of Landscape Plants in the Southern to Mid-Atlantic Region
Authors: Young R.E. , Dunlap J.L. , Smith D.J. , Hale S.A.
Published: August 2020

Rapid, wide fluctuations in winter temperatures in Mid-Atlantic and Southern states can result in severe damage to container grown landscape plants. Freezes on Christmas Day, 1983 and January 21, 1985 left nurserymen in this region with multimillion dollar losses and an interest in low-cost freeze protection methods. This study examines the cold protection properties of white copolymer and clear poly 6 mil plastics for covering unheated propagation hoop houses and for wrapping container growing beds. Soil, canopy, house ambient and outside temperatures were collected by computer on 15 minute intervals for a 3 month period. Diurnal temperature fluctuations were 1.5 to 2 times greater in clear poly than white copolymer. Double layer plastic coverings maintained minimum soil and canopy temperatures significantly higher than single layer structures. White copolymer wrapping of growing beds afforded root protection to Asian jasmine (Trachelospermum asiaticum Lem.) and Burford holly (Ilex cornuta Lindl ‘Burford Nana’) with some border damage; Wiltonii juniper (Juniperus horizontalis Moench. ‘Wiltonii’) did not need covering. White copolymer offers greater freeze protection at a lower cost.
Analyses of Landscape Design and Maintenance Requirements in Urban Parking Lots
Authors: Pfeiffer Christina A. , Wott John A. , Clark James R.
Published: August 2020

Four Seattle-area transit parking lots were used as case studies in assessing the relationship between design and construction practices and future landscape management. Soil compaction and inadequate irrigation appeared to have the greatest impact on plant survival and vigor. Other problems identified included inappropriate plant selection, out-dated and vague construction specifications, and conflicts between planting bed design and pedestrian traffic patterns. The combination of such factors decreased the effectiveness of the plantings and increased maintenance efforts in urban parking lots. Long-term maintenance problems may be avoided with plant selection/specification review and maintenance requirement/cost projections during the design stage.
Response of Dianthus barbatus L. To Preemergence Herbicides
Authors: Jacobson Julie A. , Klett James E.
Published: August 2020

Six different preemergence herbicides including one herbicide combination were applied to container-grown Dianthus barbatus L. (Sweet William) and evaluated for their effects on weed control, plant growth and phytotoxicity. Napropamide (Devrinol 10G), oryzalin (Surflan 40.4% AS), oxyfluorfen + oryzalin (Rout GS-3G), oxadiazon (Ronstar 2G), metolachlor (Dual 8EC), simazine (Princep 4G) and Dual and Princep were applied to container-grown Sweet William and studied for a growing season. Weed seeds sown were yellow foxtail, annual bluegrass, common groundsel, common chickweed, and creeping woodsorrel. Devrinol, Surflan, and Rout GS resulted in the best weed control without affecting the overall growth of Sweet Wiliam or resulting in any phytotoxicity at rates applied. Dual and Princep resulted in phytotoxicity at all rates applied on Sweet William to a degree that would make the plants unsalable.
Effects of Irrigation Rate and Media on Growth of Acer rubrum L. in Large Containers
Authors: Martin Chris A. , Ponder Harry G. , Gilliam Charles H.
Published: August 2020

Acer rubrum L. seedlings were grown in 38 1 (# 10) containers with 4 irrigation rates of 50%, 100%, 200%, 400% replacement of net evaporation and 3 media types of 100% pine bark; pine bark:sand (4:1 by vol); pine bark:sand (3:2 by vol). A spray stake irrigation system was used to irrigate. Height growth was not affected by irrigation rate. Caliper growth increased cubicly and linearly with increased irrigation rate during the first and second years, respectively. Media affected height and caliper growth the second year only. Height and caliper growth increased linearly with increased sand content. An increase in irrigation rate produced a larger root system, while an increase in sand content increased primary and secondary root growth.
Effect of Transplanting Practices on Growth and Water Relations of ‘Colt’ Cherry Trees During Reestablishment
Authors: Ranney T.G. , Bassuk N.L. , Whitlow T.H.
Published: August 2020

Dormant pruning, a film antitranspirant, and soil-applied paclobutrazol were evaluated as transplanting treatments in newly transplanted ‘Colt’ cherry trees under irrigated and water-stressed conditions. Under irrigated conditions all three treatments were effective in reducing plant water loss. However, all three treatments resulted in large reductions in mean growth rate, mean relative growth rate, root dry weight, and root surface area. The pruning treatment had no effect on the leaf area:root area ratio whereas the antitranspirant treatment resulted in an increased leaf area:root area ratio, a response considered undesirable. Paclobutrazol decreased the leaf area:root area ratio but also induced abnormal radial enlargement of plant roots. Under water-stressed conditions all three treatments were effective in reducing plant water loss and were successful in delaying plant water stress. Both pruned and antitranspirant treated plants had improved relative growth rates as compared to the controls.
Influence of Growth Medium pH on the Growth of Container-grown Fraser Fir Seedlings
Authors: Bryan James A. , Seiler John R. , Wright Robert D.
Published: August 2020

Seedlings of Fraser fir (Abies fraseri (Pursh) Poir.) were grown in sphagnum peat amended with 0 to 8 kg dolomitic limestone/m3 (0 to 13.5 lb/yd3). Initial pH ranged from 3.9 to 6.7. Best growth (21.2 cm (8.3 in) mean height at 19 months) was achieved with 1 and 2 kg/m3 (1.7 and 3.4 lb/yd3), with initial mean pH 4.2 and 4.5. Seedlings grown in media amended with 4 and 8 kg/m3 (6.7 and 13.5 lb/yd3) grew more slowly (17.4 (6.9 in) and 9.5 cm (3.7 in) in 19 months), and many were chlorotic, with poorly formed, blackened roots. At the conclusion of the first growth cycle (10 months), the slowest growth occurred in the most heavily limed peat (8 kg/m3 (13.5 lb/yd3), initial pH 6.8). Slower growth at 4 kg/m3 (6.7 lb/yd3, initial pH 5.0) became evident only after three growth cycles. Seedlings grew best within a fairly narrow range of pH (4.2 to 4.5), which is considerably more acidic than is generally recommended for conifers.
Lifting Date Influences the Ability of Auxins to Promote Root Regeneration of Colorado Spruce
Authors: Carter Joseph E. , Tripepi Robert R.
Published: August 2020

The inability of older conifer seedlings to regenerate new roots after bare-root transplanting can lead to plant death. Lifting date and auxin treatments were evaluated for their effects on root regeneration of Colorado spruce (Picea pungens Engelm.). Roots of five-year-old plants were treated monthly during fall and spring with 1000, 5000, or 10,000 mg/L of indole-3-butyric acid (IBA), 5000 mg/L of phenyl indole-3-thiolobutyrate (P-ITB), or 100% ethanol (control). After treatment, plants were grown in a greenhouse for 30 days before total number, length and dry weight of new roots were determined. Spruces treated with 1000 and 5000 mg/L of IBA in November had the greatest new root weight (1.4 g) and number (5000), respectively, per plant compared to 0.1 g and 200 roots per plant for controls. Plants dug in May produced the least number, weight and length of new roots for all treatments. Plants treated with P-ITB produced consistently greater numbers of new roots over the first three lifting dates than did controls. Absolute ethanol appeared to inhibit root regeneration. Data indicate that lifting date affected the ability of auxin to stimulate root regeneration on bare-root Colorado spruce.
Nitrogen Nutrition of Container Grown Hemerocallis × ‘Stella de Oro’
Authors: Perry Leonard P. , Adam Sinclair A.
Published: August 2020

We compared growth for plants 90 days from potting in 4 1 (# 1) nursery pots and growing outd oors in either peat moss: sandy loam: perlite (2:2:3 by vol) or peat moss : pine bark : perlite (1:1:1 by vol). Both media received the same nutrient charge and fertilizer treatments. During the 1985 season we applied weekly fertilizer levels of 0, 100, 200, 300, 400, 500, and 600 ppm of reagent grade ammonium nitrate, to which was added 125 ppm potassium chloride. During the 1986 season we repeated the study with fertilizer levels of 0, 400, 800, and 1200 ppm ammonium nitrate. For fertilizer levels there were significant differences in plant width, grade, fresh and dry weights and sum of fans—sum of fan diameters 2 cm (0. 8 in) above soil surface—both years with 400 ppm resulting in optimum growth. For media there were no differences during 1985, but there were significant differences for fresh and dry weights during 1986, and for root dry weight and fresh weight gain, with the highe st means from the soil-based medium.
Leaf and Stem Cold Hardiness of 17 Broadleaf Evergreen Taxa
Authors: Dirr Michael A. , Lindstrom Orville M.
Published: August 2020

The leaves and stems of 17 broadleaf evergreen taxa were screened for cold hardiness in laboratory tests. Leaves of Ilex were generally less cold hardy than stems. However, the leaves of I. × koehneana ‘Wirt L. Winn’, Ilex latifolia and Ilex ‘Lydia Morris’ were equal to or more cold hardy than the stems. Maximum cold hardiness of most taxa occurred in mid-January. Ilex opaca, Ilex opaca, ‘Greenleaf’, and Ilex × attenuata ‘Foster's #2,’ were the most cold hardy. Among the Ilex × attenuata cultivars, ‘Foster's #2’ was more cold tolerant than ‘Savannah’ and ‘East Palatka.’ Ilex latifolia and Ilex ‘Lydia Morris’ were least cold hardy. I. ‘Nellie Stevens’ and I. × koehneana ‘Wirt L. Winn’ were intermediate.

Osmanthus heterophyllus ‘Gulftide’ was the hardiest tea-olive, followed by Osmanthus americanus, Osmanthus × fortunei and Osmanthus heterophyllus ‘Rotundifolius’.

Prunus laurocerasus ‘Zabeliana’ was hardier than ‘Schipkaensis’ than ‘Otto Luyken’. The actual differences, however, were slight.
Effect of Nitrogen, Phosphorus and Potassium Rates on Severity of Xanthomonas Leaf Spot of Schefflera
Authors: Chase A.R.
Published: August 2020

Brassaia actinophylla plants were grown with various N-P-K regimes prior to inoculation with Xanthomonas campestris pv. hederae. Increased rates of N, P, and K reduced the number of lesions. The number of leaves, height, and shoot quality decreased as the nitrogen rate increased, but were not consistently affected by phosphorus or potassium rates. Severity of Xanthomonas leaf spot on Brassaia actinaphylla can be minimized with slight to moderate increased N, P, or K rates with N rate having the greatest impact on disease severity.
Chemically Induced Branching of Woody Landscape Plants
Authors: Keever Gary J. , Foster William J.
Published: August 2020

Axillary budbreak of Ilex Crenata Thunb. ‘Helleri’ and ‘Ilex vomitoria’ Ait. ‘Stoke's Dwarf’ hollies was promoted by a single BA (N-(phenylmethyl)-1H-purin-6-amine) application of 125–1000 ppm compared to an unpruned control. Budbreak of Photinia × Fraseri Dress was stimulated by 500–2500 ppm BA and 2000–5000 ppm Promalin (BA + GA4+7). Budbreak in Nandina domestica Thunb. ‘Harbour Dwarf’ increased with 1000–2500 ppm BA and 2000–5000 ppm Promalin application. Budbreak of Rhododendron × ‘Formosa’ azalea was promoted by 2000 and 2500 ppm BA and 2000–5000 ppm Promalin. Axillary budbreak of Ternstroemia gymnanthera (Wight & Arn.) T. Sprague) and Raphiolepis indica (L.) Lindl. was not affected by BA or Promalin application.
Growth of Capillary-Irrigated Andorra Juniper and Sarcoxie Euonymus as Affected by Controlled Release Fertilizer Type and Placement
Authors: Hicklenton Peter R.
Published: August 2020

Juniperus horizontalis Moench. ‘Plumosa compacata’ and Euonymus fortunei Turcz. ‘Sarcoxie’ were grown on a sand capillary bed with two types of controlled release fertilizer (3:1 Type 100:Type 40 Nutricote 16N-4.4P-8.1K (16-10-10),and Osmocote 18N-2.6P-9.7K (18-6-12) either medium-incorporated, surface-applied or dibbled below the roots. Throughout the growing season, neither leaf area, root or shoot dry weight of euonymus was affected by fertilizer type or placement. Branch length growth and dry weight of juniper was not affected by fertilizer type when fertilizer was surface-applied or medium incorporated. Dibbled Osmocote produced similar results, but dibbled Nutricote resulted in poor root and shoot development in juniper throughout the season. Medium soluble salt concentration (determined on container leachate) was 2800 dS/m in the dibbled Nutricote treatments in June (approximately 2.5 times higher than that in the other treatments). Soluble salts decreased between June 21 and August 16 in all treatments and then remained quite constant until the end of the season (September 13).
Effect of Air and Growing Medium Temperatures on Rhizoctonia Foot Rot of Epipremnum aureum
Authors: Chase A.R. , Poole R.T.
Published: August 2020

Air and growing medium temperatures affected severity of foot rot of Epipremnum aureum (pothos) caused by Rhizoctonia solani AG4. Maximum daily temperatures of 30°C (86°F) for either air or soil resulted in optimal disease development. Maximum daily temperatures of 35°C (95°F) decreased disease development significantly due to fungal pathogen growth reduction. A continuous temperature of 30°C (86°F) was also too high for significant disease development.
Leachate Electrical Conductivity and pH for Ten Foliage Plants
Authors: Poole R.T. , Conover C.A.
Published: August 2020

Most foliage plant varieties tested produce salable plants when fertilized with a wide range of rates. About 5 grams 19N-2.6P-10K (19-6-12) per 15 cm pot per 3 months resulted in best Dracaena fragrans ‘Massangeana’, Nephrolepis exaltata ‘Compacta’, and Philodendron s. oxycardium. No more than 2.4 grams per pot appears best for Chamaedorea elegans. Aglaonema ‘Silver Queen’, Aphelandra squarrosa ‘Dania’, Codiaeum variegatum ‘Banana’, Spathiphyllum ‘Petite’, Dieffenbachia maculata ‘Camille’ and Epipremnum aureum ‘Marble Queen’ grew best at about 10 grams per pot per 3 mos. Only P. s. oxycardium and C. elegans had a narrow requirement for fertilization levels. Electrical conductivity (EC) of leachate obtained from pots of best quality plants had a very wide range indicating leachate EC is a poor indicator for production of quality plants.
Growth Inhibition of Ericaceous Plants from Metolachlor
Authors: Frank J. Ray , Beste C. E.
Published: August 2020

Yellow nutsedge (Cyperus esculentus L.) is a major weed problem in many perennial woody crops. Dual 8E4 (metolachlor) at 4.5, 6.7, 9.0 and 13.5 kg/ha (4, 6, 8 and 12 lb/A) was evaluated in the field for 4 years to determine phytotoxicity to 11 varieties of azaleas. Also evaluated were Ericaceous species including coast leucothoe, compact Japanese andromeda, and Rhododendron × ‘PJM’. Fall or spring applications of metolachlor at rates up to 13.5 kg/ha (12.0 lb/A) caused no injury to the established azaleas ‘Delaware Valley White’, ‘Hershey Red’ and ‘Hinocrimson’. Some temporary injury occurred to newly planted ‘Hinocrimson’ azaleas treated with metolachlor at 6.7 kg/ha (6.0 lb/A). A July application at this same rate caused some temporary injury to established ‘Delaware Valley White’, ‘Double Pink’, ‘Hershey Red’, ‘Hot Shot’, ‘Karen’, ‘Lady Robin’, ‘Rosebud’ and ‘Tradition’ azaleas and ‘Coast lecothoe’ and ‘PJM’ rhododendron. No reduction in crop quality or size was observed with any species at time of crop harvest.
Plant Response to Container Planting Method and Media
Authors: Keever Gary J. , Cobb G.S.
Published: August 2020

Shoot dry weight and relative root density of Ilex crenata Thunb. ‘Compacta’ and Rhododendron obtusum (Lindl.) Planch. ‘Hino Crimson’ were greater when liners were transplanted into holes with a core removed (excavated) compared to holes formed by compression (dibbled). Growth index, relative root density, and shoot dry weight increased as the percent pine bark in the growth media increased from 50% to 80 or 90% pine bark with holly and from 50% to 90% pine bark with azalea. Bulk density decreased and air porosity and irrigation frequency increased as the percent pine bark in pine bark:sandy loam container media increased from 50% to 100%. In a second experiment, root density and shoot dry weight of Ilex crenata Thunb. ‘Helleri’, but not Rhododendron × ‘Trouper’, were greater in pine bark and pine bark-sandy loam media when the planting hole was excavated rather than dibbled. Plant growth of the 2 species in peat-based media was not influenced by planting method.
Tree Root Growth and Development. II. Response to Culture, Management and Planting
Authors: Gilman Edward F.
Published: August 2020

Cultural factors influencing root growth in the landscape or nursery include soil management, irrigation, fertilization, shoot pruning and root pruning. These affect root density, depth of penetration, spread, vertical distribution in the soil profile and mineral uptake. Root morphology varies widely among genera, species and individuals within a species. The distribution, length and weight of roots within the root ball of transplanted field-grown trees can be modified with cultural management practices. Growth of transplanted trees may be affected by these modifications. Root spread diameter increases at a rate of 0.9–2.4 m (36–96 in)/year following planting. From 1 to 10 years is required to replace the pre-transplant root system for trees transplanted from field nurseries. Root system in urban environments can be modified by cultural techniques which direct their growth.
Chilling and Bud Break in Silver Maple2
Authors: Ashby W. Clark , Bresnan Damian F. , Huettemen Carl A. , Preece John E. , Roth Paul L.
Published: August 2020

Silver maple (Acer saccharinum L.) goes dormant in the autumn and is greatly delayed in bud break unless the buds are exposed to prolonged low temperature. Approximately 1000 hours below 4°C (39°F) under natural conditions (early March in southern Illinois) will bring about bud break 2 to 3 weeks after juvenile plants are put under favorable growing conditions. Chilling in a dark cold room at 4°C (39°F) separated from natural changes required a greater number of hours, approximately 2000, for a similar response. Bud break for subterminal buds was earlier than for terminal buds on insufficiently chilled stem segments or larger plantlets. Terminal buds broke first with longer chilling periods. Rooted cuttings from adult trees had a greater chilling requirement than juvenile plant material, either micropropagated plantlets or segments from shoots. No geographic or provenance variation in response to chilling was observed within 11 provenances ranging from Mississippi to central Ontario to New Hampshire to West Virginia. Silver maple was similar to sugar maple and basswood in its chilling requirement. It was unlike red maple which has a chilling requirement in some but not all parts of its range.
Seasonal Abundance and Control of the Rhododendron Gall Midge, Clinodiplosis rhododendri (Felt), in Container Grown Rhododendron catawbiense Michaux
Authors: Hanula James L.
Published: August 2020

The seasonal abundance and control of the rhododendron gall midge, Clinodiplosis rhododendri (Felt), were investigated on container grown Rhododendron catawbiense Michaux. Most of the midge population studied completed 3 generations, and at least some completed 4–5 generations during the growing season (May–October 1989). Adults that developed from overwintered larvae began emerging on May 14, 1989. Three of the peaks in adult emergence coincided with bud break during the three growth flushes observed in the nursery. Only 20% of the buds were infested during the first growth flush, while 95% were infested during the second and third growth flushes. The low level of infestation during the early growth period provides an opportunity to detect an infestation before extensive damage occurs.

Five insecticides were tested as soil drenches to control overwintering larvae. All five were equally effective and reduced the number of emerging adults by 95–100%. Further tests with Dursban 2E (chlorpyrifos) showed that soil surface applications were also effective, and that the timing of irrigation did not affect control. Soil drenches with two additional materials, Safer's insecticidal soap and Pratt horticultural oil, were not effective.
Stock Plant Nutrition Influences the Adventitious Rooting of ‘Rotundifolia’ Holly Stem Cuttings
Authors: Rein William H. , Wright Robert D. , Wolf Dale D.
Published: August 2020

Containerized stock plants of Ilex crenata Thunb. ‘Rotundifolia’ were liquid-fertilized at least three times per week with nitrogen (N) at five rates (25, 50, 100,200, and 300 mg N/l) and in two forms (100% NH4NO3 or 50% NH4NO3 + 50% urea) in a factorial treatment design. Phosphorus and potassium were included in a constant ratio with N (100 N:15 P:50 K). Leaf and stem percent N levels were suboptimal at the lowest fertilizer rate and excessive at the highest fertilizer rate. Percent rooting of stem cuttings decreased linearly with fertilizer rate. With increasing fertilizer rates, total nonstructural carbohydrate (TNC) levels increased in leaves and remained constant in stems. Stem cutting percent moisture increased and was highly correlated with fertilizer rate. The form of N applied made no statistical difference in these trends. The decrease in percent rooting with increasing fertilizer rates was attributed to increases in shoot growth activity and decreased tissue maturation.
Whole-Plant Response of Selected Woody Landscape Species to Uniconazole
Authors: Warren Stuart L. , Blazich Frank A. , Thetford Mack
Published: August 2020

Uniconazole was applied as a foliar spray or medium drench to six woody landscape species: ‘Sunglow’ azalea; flame azalea; ‘Spectabilis’ forsythia; ‘Compacta’ holly; ‘Nellie R. Stevens’ holly; and mountain pieris. One hundred days after uniconazole application, leaf, stem, and top dry weight of all species, except flame azalea and mountain pieris, decreased as uniconazole concentration increased. Compared to controls, stem and leaf dry weight were reduced by uniconazole 18 to 60% and 13 to 32%, respectively, depending on species and method of application. Stem dry weight was reduced to a greater degree, compared to leaf dry weight. For all species, drench application was more effective than foliar spray in reducing leaf, stem, and top dry weight. Leaf area of ‘Spectabilis’ forsythia and ‘Nellie R. Stevens’ holly decreased with increasing rates. However, specific leaf weight was not affected. Uniconazole did not significantly affect leaf net photosynthetic rate, stomatal conductance or internal leaf CO2 concentrations in ‘Spectabilis’ forsythia or ‘Nellie R. Stevens’ holly. No phytotoxicity was observed on any species.
Mist Water Quality, Rooting Hormone, Collection Time, and Medium Effect on Propagation of Pittosporum Tobira (Thunb.) Ait.
Authors: Wang Yin-Tung
Published: August 2020

Cuttings of Japanese pittosporum (Pittosporum Tobira (Thunb.) Ait.) were collected in February, April, June, October and December 1987 and rooted in a mist propagation bed with 0, 1250, 2500, 5000 or 10000 mg/l (ppm) IBA in 50% ethanol under a mist of low-salt (EC ≤ 0.03 dS/m) or saline (EC = 0.96 to 1.50 dS/m) water. Regardless of collection time, IBA either did not improve or adversely affected rooting. Rooting percentages of all cuttings were acceptable with no response to water salinity, except those collected in June which had poor performance when misted with saline water. In another test, P. Toblra cuttings rooted in fine grade vermiculite and equal volumes of perlite and coarse grade vermiculite had superior performance to perlite.
Production and Postproduction Performance of Uniconazole-Treated Bedding Plants
Authors: Keever Gary J. , Foster William J.
Published: August 2020

Growth and flowering responses of Pelargonium × hortorum L. H. Bailey ‘Ringo Deep Scarlet’, Tagetes erecta L. ‘Inca Orange’, Viola × wittrockiana Gams. ‘Blue Shades’, Impatiens × ‘Zenith’ and Salvia farinacea Benth. ‘Victoria Blue’ to uniconazole applied at the seedling stage were evaluated at the end of production and 5 to 7 weeks after transplanting into the landscape (geranium, impatiens and salvia only). A drought stress evaluation was also conducted. Response to uniconazole varied with species, sampling date and uniconazole concentration. Growth of all species was suppressed when measured 4½ to 8½ weeks after treatment (WAT), and stress tolerance of all species except marigold increased with increasing concentrations of uniconazole. Flowering generally was delayed with uniconazole. Impatiens and geranium treated with 10 ppm or less of uniconazole were similar in height to nontreated plants 5 to 7 weeks after being transplanted; at this time, uniconazole had no effect on plant height or shoot dry weight of salvia. Daminozide applied once as a 5000 ppm foliar spray was not effective in suppressing vegetative growth of any of the tested species.