bluuebunny/crossref_metadata_2025 huggingface dataset:
Height Control of Picea spp. and Chamaecyparis lawsoniana with Uniconazole and 6-Benzyladenine
Authors: Duck M.W. , Cregg B.M. , Fernandez R.T. , Heins R.D. , Cardoso F.F.
Published: August 2020

The use of plant growth retardants (PGRs) could benefit conifer growers by enabling them to produce more uniform, live tabletop Christmas tree specimens. We applied two PGRs to determine effectiveness on height control and terminal bud density for the following species of conifer seedlings: Black Hills spruce (Picea glauca var. densata), Serbian spruce (P. omorika), Colorado blue spruce (P. pungens), and Port Orford cedar (Chamaecyparis lawsoniana). The chemicals were applied at 2-week intervals throughout an 8-week period for a total of four applications. Uniconazole was applied as a foliar spray and soil drench (5 and 1 ppm, respectively), 6-benzyladenine (BA) was applied as a foliar spray (500 and 1000 ppm), and the control did not receive a PGR application. Uniconazole was generally effective on the spruces but not on Port Orford cedar, whereas BA reduced height of all species and increased spruce bud densities. However, BA treatments were phytotoxic in all species tested. The drench of uniconazole caused minor phytotoxicity in Black Hills spruce, whereas foliar applications to Port Orford cedar had minor phytotoxic effects.
Evaluation of Twelve Genotypes of Hibiscus for Resistance to Hibiscus Sawfly, Atomacera decepta Rohwer (Hymenoptera: Argidae)
Authors: Boyd David W. , Cheatham Christopher L.
Published: August 2020

Twelve genotypes of hibiscus were evaluated for resistance to hibiscus sawfly, a minor pest of hibiscus. Evaluations were conducted by counting eggs deposited on the hibiscus and larvae feeding on the hibiscus. Plants were evaluated at the end of the study with a damage rating. Three genotypes demonstrated resistance or tolerance to sawfly feeding: Hibiscus acetosella, H. aculeatus, and H. grandiflora. All three of these genotypes had few, if any, eggs or larvae and were given the lowest damage rating among the genotypes evaluated.
Growing Pinus nigra Seedlings in Spinout™-Treated Containers Reduces Root Malformation and Increases Growth After Transplanting
Authors: Zahreddine Hala G. , Struve Daniel K. , Quigley Martin
Published: August 2020

Root malformation originating during container production causes mechanical instability and plant mortality when those seedlings are transplanted. We investigated the effects of chemical (interior container surfaces treated with Spinout™ or not) or mechanical container modifications (vertical slits or no vertical slits), and the effects of substrate bulk density on the growth of Pinus nigra (Arnold) seedlings during plug production and after transplanting. Seedlings grown in compacted substrate had the greatest shoot, root and total plant dry weights five months after seeding in plug trays. However the incidence of root malformation was also greatest when seedlings were grown in compacted substrate. Unless root pruned, root malformations were retained after transplanting. Seedlings with unpruned roots grown in Spinout™-treated containers had higher regenerated root dry weight than those grown in untreated containers four months after transplanting. Root pruning before transplanting reduced growth of the seedlings regardless of container configuration and of substrate bulk density. Root regrowth and seedling quality after transplanting were greatest for seedlings grown in the treatment combination of no Spinout™, compacted substrate and no slits. Seedlings produced under natural photoperiods formed a resting bud when the seedlings were approximately 2.5 cm (1 in) tall in spring season. Within two weeks shoot elongation resumed, which resulted in branched seedlings. Root malformation can be induced during plug production and is retained after transplanting unless corrected by root pruning.
Provenance and Production Location Affects Growth and Quality of Quercus phellos and Q. shumardii Seedlings
Authors: Pounders Cecil , Fare Donna C. , Cheatham Christopher
Published: August 2020

Seed origin is an important part of oak production that is often ignored by many shade tree growers when selecting material for production. Results of this study indicate interactions between seed sources and production environments have a marked effect on growth and quality of seedlings of willow (Quercus phellos L.) and shumard (Q. shumardii Buckl.) oak in the first two years of production. Seedlings from selected provenances, grown in different hardiness zones, varied more in plant height than trunk caliper and quality. Seedlings from the southern part of the native range of the two species generally grew better in both climates the first growing season. After the second season, total height growth for the various provenances indicated provenance genotype was more important than where seeds were collected. Provenances from the southern native range did not out perform those collected from the central and northern sectors. Exposing seedlings from various provenances to four environmental regiments at two production locations (MS-TN, TN-MS, MS-MS, and TN-TN; referring to year1-year 2, respectively) was more effective at detecting seedlings from provenances with broad environmental adaptation than simply comparing growth at the two locations.
A Comparison of Subcanopy Versus Overhead Application of Constructed Wetland Treated Nursery Runoff on Short and Long Rotation Nursery Crops
Authors: Arnold Michael A. , Lesikar Bruce J. , McDonald Garry V. , Wilkerson Don C.
Published: August 2020

The nursery/greenhouse industry is the fastest growing segment of U.S. agriculture. Consumer demand for excellent product quality requires luxury applications of water and agricultural chemicals. These cultural practices tend to yield significant volumes of runoff rich in nutrients and pesticides. A capture and recycle system at the Nursery/Floral Crops Research and Education Center at Texas A&M University was fitted with 12 gravel filtration sub-surface flow (SSF) and 12 bog-like free-surface flow (FSF) wetland cells. Three cells of each type were planted with Canna x generalis Bailey ‘Cherry Red’, Iris L. x ‘Clyde Redmond’, both species, or no wetland plants. Runoff was continually collected from the nursery and recycled through wetland cells prior to application via overhead impact sprinklers or subcanopy microsprinklers. Short-term (10 wk) differential effects between overhead and subcanopy irrigation during production of Fraxinus pennsylvanica, Pistacia chinensis von Bunge, Quercus virginiana P. Miller, and Taxodium distichum (L.) Richard in 9.4 liter (#3) containers or Ilex vomitoria W. Aiton ‘Nana’ and Catharanthus roseus G. Don in 5.8 liter (#2) containers were limited in magnitude. However, overhead irrigation reduced height and caliper growth or injured the foliage compared to plants irrigated with subcanopy microsprinklers during longer-term (14 months) production in large 87.9 liter (#27) containers. The extent of reduction was species dependent with Pinus elliottii Englemann being minimally impacted, Pyrus calleryana Descaisne ‘Bradford’ intermediate, and Lagerstroemia L. x ‘Basham's Party Pink’ (purportedly a Lagerstroemia indica L. x Lagerstroemia fauriei B. Koehne hybrid) and T. distichum exhibiting more pronounced effects. Damage appeared to be largely a result of high dissolved salt concentrations in irrigation water contacting the foliage. Recycling of runoff through the FSF cells concentrated soluble salts more so than passing the water through the SSF cells. Efficacy of nitrate nitrogen removal varied with species, season, loading rate, and wetland type. However, the constructed wetlands were generally effective under our test conditions at maintaining effluent nitrate levels at ≤10 mg/liter (10 ppm) when loading rates were ≤50 mg/liter (50 ppm). Presence of emergent wetland plants (those with roots imbedded in the substrate and shoots extending above the water surface, rather than floating or submerged plants) in the system was more important for effectively reducing nitrate levels in effluent from SSF than from FSF cells.
Plant Regeneration of Chokecherry (Prunus virginiana L.) from in vitro Leaf Tissues
Authors: Dai Wenhao , Jacques Victoria , Walla James A. , Cheng Zong-Ming
Published: August 2020

An effective plant regeneration system was developed for chokecherry (Prunus virginiana L.) by using in vitro leaf tissues. Adventitious shoots regenerated from in vitro leaf tissues only when cultured on Woody Plant Medium (WPM), but not on Murashige and Skoog medium, supplemented with benzyladenine (BA) or thidiazuron (TDZ). Three chokecherry clones (NN, 10, and 17) responded differently to types and concentrations of cytokinins, ranging from 16.7 to 91.7% leaf explants regenerating shoots. A mean of four shoots was produced from each explant, with the most shoots (> 10) from clone NN on media with 5–10 μM BA. Higher concentrations of TDZ (> 8 μM) caused serious vitrification and eventual death of newly induced shoots. Regenerated shoots (> 1.5 cm) produced roots in vitro in half strength MS medium or ex vitro in Cellular Rooting Sponge (CRS) rooting plugs with or without auxin (NAA or IBA) treatments. Rooting was affected by auxin, genotypes, and the rooting methods.
Effect of Nickel Applications for the Control of Mouse Ear Disorder on River Birch
Authors: Ruter John M.
Published: August 2020

Mouse ear (leaf curl, little leaf, squirrel ear) disorder has been a problem in container-grown river birch (Betula nigra L.) for several decades. The disorder is easy to detect in nurseries as the plants appear stunted due to shortened internodes which give the appearance of a witches-broom. The leaves are small, wrinkled, are often darker green in color, are commonly cupped and have necrotic margins. Plants grown in soil rarely express the disorder. A trial was initiated in June 2003 to determine if a deficiency of nickel was the cause of mouse-ear on river birch. Symptomatic river birch trees (Betula nigra ‘BNMTF’ Dura-Heat™) in their second growing season in #15 containers were selected for uniformity of size and mouse ear. Treatments included a 1) control, 2) 789 ppm Ni sprays, 3) 394 ppm Ni sprays, 4) 0.005 lbs Ni/yd3 as a drench, 5) 26 g/pot triple superphosphate (0–46–0), and 6) 130 g/pot Milorganite. Nickel was applied as nickel sulfate, whereas triple superphosphate and Milorganite contain trace amounts of nickel. At 16 days after treatment, up to 5 cm of new growth was evident on plants sprayed with nickel. Thirty days after treatment shoot length increased up to 60%, leaf area increased 80 to 83%, and leaf dry mass increased 76 to 81% for plants sprayed or drenched with nickel sulfate. Plants treated with triple superphosphate or Milorganite did not resume normal growth. All plants treated with nickel sulfate in 2003 did not show symptoms of mouse ear after initiation of growth in 2004. Based on this research mouse ear disorder of river birch is caused by a deficiency of nickel which can be corrected by foliar or drench applications of nickel sulfate.
Seed Germination of Seabeach Amaranth (Amaranthus pumilus) as Influenced by Stratification, Temperature, and Light
Authors: Blazich Frank A. , Warren Stuart L. , Nash David L. , Reece William M.
Published: August 2020

Freshly harvested seeds of seabeach amaranth (Amaranthus pumilus Raf.) were stratified (moist-prechilled) for 0, 30, 60, 90, or 120 days. Following stratification, seeds were germinated at 25C (77F) or an 8/16 hr thermoperiod of 30/20C (86/68F) with daily photoperiods at each temperature of 0 (total darkness) or 16 hr. Germination was recorded every 3 days for 30 days. Regardless of photoperiod or duration of stratification, germination at 25C (77F) was negligible. After 120 days of stratification, total (30-day) germination at 25C (77F) with photoperiods of 0 or 16 hr was 4 and 3%, respectively, whereas considerable germination occurred at 30/20C (86/68F). Germination increased linearily with increasing durations of stratification for both photoperiods when seeds were germinated at 30/20F (86/68F). In addition, germination increased when seeds were exposed to light. After stratification of 30 days and germination in the dark at 30/20C (86/68F), germination of 20% was observed by day 12 and increased to 27% by day 30, whereas for seeds exposed to a 16-hr photoperiod, 16% germination was noted by day 12 increasing to 38% by day 30. Following stratification of 120 days and germination in the dark at 30/20C (86/68F), germination of 49% was observed by day 12 increasing to 50% by day 30, whereas for seeds exposed to light, 82% germination was realized by day 12 increasing to 85% by day 30.
BA Application Frequency and Concentration Effects on Two Indian Hawthorn Cultivars
Authors: Oates Jayme M. , Keever Gary J. , Kessler J. Raymond
Published: August 2020

Benzyladenine (BA) is a synthetic cytokinin that promotes lateral shoot development in herbaceous and woody ornamentals and may be a viable alternative to mechanical pruning in nursery production. A study was conducted to determine the effects of BA application number, interval and concentration on two Indian hawthorn [Rhaphiolepis Lindl. Cor. Poir. indica (L.) Lindl. (Crataegus indica L.)] cultivars. In spring 2002, actively growing ‘Olivia’ and ‘Eleanor Taber’ received three applications of 2500 or 5000 ppm BA at a one-, two-, or three-week interval. Data collected four weeks after initial treatment (WAT) reflected the effects of one, two, or three BA applications at each concentration. At this time new shoot counts in both cultivars and foliar injury in ‘Olivia’, but not in ‘Eleanor Taber’, increased with increasing number of applications and BA concentration. Data collected 12 WAT reflected the effects of BA application interval and concentration. At this time new shoot counts increased with decreasing application interval in ‘Olivia’, while ‘Eleanor Taber’ formed the most new shoots when BA was applied at a two-week interval. All treated plants sustained minimal to moderate injury to immature foliage. The experiment was repeated in 2003 using 1750 ppm and 3500 ppm BA on ‘Olivia’ Indian hawthorn. Applications were halted at the first sign of foliar injury resulting in plants treated at one, two, and three-week intervals receiving three, two, and two applications, respectively. New shoot counts on ‘Olivia’ treated at the three application intervals were similar, but greater than those on untreated plants. Control plants had a foliar injury rating similar to that of plants treated at a two or three-week interval, but less than that of plants treated at a one-week interval. Growth index was not affected by treatment in either year.
DNA Fingerprinting of Clones and Hybrids of American Elm and Other Elm Species with AFLP Markers
Authors: Pooler Margaret R. , Townsend A.M.
Published: August 2020

The elms represent a diverse group of widely distributed temperate trees that are valued for forest products as well as landscape plants. Genetic diversity was examined among 43 Ulmus accessions, including 19 accessions of American elm and representatives of seven other species. Data from 135 markers from five AFLP primer pairs were used to estimate genetic similarity among accessions and to construct a UPGMA-derived dendrogram. While the species clusters were generally well-resolved, the relationships among clones and hybrids of American elm were less distinct. Our data provides some evidence to support the hybrid origin of two previously unverified U. parvifolia × U. americana clones, and provides evidence that the new clone N3487 (‘Jefferson’), an elm whose origin has been questioned, is an American elm.
Efficacy and Costs Associated with the Manual Removal of Bagworms, Thyridopteryx ephemeraeformis, from Leyland Cypress
Authors: Lemke Hans D. , Raupp Michael J. , Shrewsbury Paula M.
Published: August 2020

Bagworms (Thyridopteryx ephemeraeformis) are a common pest of landscape plants. The efficacy and costs were determined for the manual removal (handpicking) of bagworms from a single Leyland cypress (X Cupressocyparis leylandii) and estimated for a planting of 40 trees. Manual removal costs were compared to the estimated costs of spraying trees with the insect growth regulator tebufenozide. Handpicking the bags provided 92% control and required 160 minutes for one tree and an estimated 6,400 minutes for 40 trees. Labor costs for manual removal were estimated at $44 for one tree and $1764 for 40 trees. Estimated time required to spray a single tree was 71 minutes while 40 trees required an estimated 251 minutes. Estimated cost to spray one tree was about $28 and the cost for 40 trees was estimated to be $105. The time spent and costs of control are similar for handpicking and spraying single trees. Handpicking may be acceptable on single or small numbers of short trees that may be safely handpicked. However, as the number of trees increases, time and costs associated with handpicking increase dramatically, while costs to spray increase only slightly.
Landscape Plant Material, Size, and Design Sophistication Increase Perceived Home Value
Authors: Behe B. , Hardy J. , Barton S. , Brooker J. , Fernandez T. , Hall C. , Hicks J. , Hinson R. , Knight P. , McNiel R. , Page T. , Rowe B. , Safley C. , Schutzki R.
Published: August 2020

Little consumer research is available to help landscape design and installation businesses develop service marketing strategies. We investigated the effect of three components of a landscape design on the perceived value of a home. This information would be useful in marketing lawn and landscape services to prospective clients. Our objective was to provide a consumer perspective on the value of the components in a ‘good’ landscape and determine which attributes of a landscape consumers valued most. Using conjoint design, 1323 volunteer participants in seven states viewed 16 photographs that depicted the front of a landscaped residence. Landscapes were constructed using various levels of three attributes: plant material type, design sophistication, and plant size. Results showed that the relative importance increased from plant material type to plant size to design sophistication. Across all seven markets, study participants perceived that home value increased from 5% to 11% for homes with a good landscape.
Sumagic (Uniconazole) Promotes Flower Bud Set on Camellia japonica
Authors: Banko Thomas J. , Landon Amelia L.
Published: August 2020

Three-year-old container-grown plants of Camellia japonica ‘Grace Albritton’, ‘Paulette Goddard’, and ‘Sea Foam’ were sprayed with a water control, B-Nine (daminozide) at 5000 ppm, Bonzi (paclobutrazol) at 80, 120, 160, 200, and 240 ppm, or Sumagic (uniconazole) at 30, 45, 60, 75, and 90 ppm in June. B-Nine and Bonzi treatments provided no increase in flower bud set but Sumagic treatments increased bud set for ‘Grace Albritten’ by up to 370% and ‘Paulette Goddard’ by 200%. In another experiment, Sumagic at 0, 45, 60, 75, and 90 ppm was applied to ‘Grace Albritton’, ‘Paulette Goddard’, and ‘Blood of China’ at three different spring growth stages: Bud swell, partial new shoot growth, and new shoots fully extended. Significant linear or quadratic increases in flower bud set occurred for all cultivars depending on application timing. Application at the two earlier stages resulted in more flowers than application at the latest (full shoot growth) stage. Sumagic decreased plant heights by 10 to 30%, depending on cultivar and application rate but this reduced the need for shearing to maintain form and compactness and made flowers more visible over the surface of the plants.
Effects of K-IBA on the Rooting of Stem Cuttings of 15 Taxa of Snowbells (Styrax spp.)
Authors: Griffin Jason J. , Lasseigne F. Todd
Published: August 2020

Currently, information regarding asexual propagation of Styrax L (snowbells) is lacking in the literature. In this study, the influence of K-IBA treatment on root production was investigated on stem cuttings of 15 different taxa of Styrax. Softwood or semi-hardwood stem cuttings dipped in 0, 3000, or 8000 ppm (0, 0.3, or 0.8%) K-IBA were evaluated for percent rooting and root number per rooted cutting. Cuttings were allowed to root under intermittent mist in a perlite:peat (3:1 by vol) rooting substrate for 9 weeks. Percent rooting and the response to K-IBA varied by species and by cultivar within a species. All 15 taxa rooted to some extent. Auxin application improved percent rooting for S. dasyanthus, S. japonicus ‘Carillon’, S. japonicus ‘Pink Chimes’, S. japonicus ‘Snowfall’, and S. tonkinensis, and decreased percent rooting for S. formosanus, S. japonicus ‘Issai’, S. japonicus ‘Pink Cascade’, and S. serrulatus (clone B). Application of K-IBA increased the number of roots produced per rooted cutting on S. calvescens, S. confusus, S. japonicus ‘Pink Chimes’, S. serrulatus (clone A), and S. tonkinensis.
Evaluation of Herbaceous Perennials as Weed Suppressive Groundcovers for Use Along Roadsides or in Landscapes
Authors: Eom Seok Hyun , Senesac Andrew F. , Tsontakis-Bradley Irene , Weston Leslie A.
Published: August 2020

Fifteen herbaceous perennials were evaluated in field experiments in two New York State locations to determine their utility in roadside and landscape areas as weed suppressive groundcovers. Four species, Alchemilla mollis, Nepeta x faassenii, Phlox subulata, and Solidago sphacelata were strongly weed suppressive in both managed (weeds removed) plots and unmanaged (weeds not removed) plots. Weed suppressivity of perennial groundcovers was significantly increased in year two in both locations when perennials were well established. The most suppressive perennials showed several similar characteristics likely associated with their successful establishment. Successful groundcovers possessed dense foliage which strongly reduced light transmittance at the soil surface and emerged relatively early in spring. Lamiastrum galeobdolon and Thymus praecox proved to be more successful over a 2-year period when managed by weed removal in early spring. Although Leymus arenarius, a relatively tall monocot, also inhibited weed growth, this species demonstrated invasive characteristics due to its spread outside plots by fast-growing rhizomes.
Weed Control for Pot-In-Pot Production using Preemergence Herbicides
Authors: Fare Donna C. , Knight Patricia , Gilliam Charles H. , Altland James
Published: August 2020

Four experiments were conducted to investigate herbicides currently labeled for field and/or container production for use in pot-in-pot production. Southern magnolia (Magnolia grandiflora L.), red maple (Acer rubrum Spach. ‘Autumn Flame’ and ‘Franksred’), ornamental pear (Pyrus calleryana Decne. ‘Bradford’ and ‘Cleveland Select’), river birch (Betula nigra L.), green ash (Fraxinus pennsylvanica Marsh. and F. pennsylvanica Marsh.‘Marshall's Seedless’), and zelkova (Zelkova serrata Spach ‘Village Green’) were evaluated for herbicide tolerance. Barricade 65WG, Surflan 4AS, and Pendulum 60WDG, used alone or in combination with Princep and Gallery 75 DF, had no adverse effect on tree shoot growth or trunk caliper growth when applied as a directed band application. Weed control varied depending upon local site conditions, herbicide rate and weed species.
Pot-in-Pot Production of Six Intermountain West Native Herbaceous Perennial Species Grown in Containers
Authors: Cardoso Guillermo , Kjelgren Roger , Cerny-Koenig Teresa , Koenig Rich
Published: August 2020

We investigated the performance of six Intermountain West (IMW) native herbaceous perennial species grown in a pot-in-pot (PIP) or conventional above-ground (CAG) production system for two years. Three different species were grown for two production cycles each year. Root zone temperature (RZT), plant and container water loss, stomatal conductance, plant height, and final biomass were measured. The RZT of plants in the PIP system were as much as 7C cooler than the CAG system, with temperature differences greater at the edge than at the center of the container. Water loss was approximately 10% lower for PIP plants on five of eight measured dates despite higher stomatal conductance on five of seven dates. Higher RZT and lower gas exchange reduced top growth more than root growth for CAG produced plants, but results varied with species and season. Conventional above-ground plants showed no visible damage but had slower growth rates compared to PIP plants. Lower elevation species were more tolerant of warmer above ground RZT, but more susceptible to winter damage. Results indicate that in areas with severe yearly temperature extremes, higher quality IMW herbaceous perennials could be grown with the PIP system in #1 containers compared to the CAG system.
Effect of Dolomitic Lime Rate and Application Method on Substrate pH and Creeping Woodsorrel Establishment
Authors: Wada Sugae , Altland James , Mallory-Smith Carol , Stang Jack
Published: August 2020

Experiments were conducted to evaluate the effect of dolomitic lime rate and application method on substrate pH, creeping woodsorrel (Oxalis corniculata) establishment in containers, and growth of azalea (Rhododendron ‘Rosebud’) and pieris (Pieris japonica ‘Claventine’). In Experiments 1 and 2, pulverized dolomitic limestone was incorporated at 0, 6, 12, 24, or 47 kg/m3 (0, 10, 20, 40, or 80 lbs/yd3). Containers were overseeded with twenty seeds of creeping woodsorrel. Substrate pH was measured with a pour-through technique. Substrate pH increased linearly and quadratically with increasing lime rate. Creeping woodsorrel shoot fresh weight was negatively correlated to substrate pH (r = −0.67, p = 0.0001). Creeping woodsorrel germinated and established poorly in substrates with pH higher than 6.7, with commercially acceptable control (>90%) occurring in containers with pH higher than 8.4 and 7.5 in Experiments 1 and 2, respectively. In Experiments 3 and 4, containers were topdressed with a uniform layer of pulverized or pelletized dolomitic limestone at 0, 5, 10, 20, or 40 g (0, 0.18, 0.35, 0.71 or 1.14 oz) per container. Substrate pH was measured in 2.5 cm (1 in) layers from the top to the bottom of the container using a modified saturated media extraction procedure. At each lime rate, pH was higher on the substrate surface than lower layers when topdressed with pulverized compared to pelletized lime. Across all lime types and rates, pH was lower in the 2.5 to 5.1 cm (1 to 2 in) layer compared to the surface layer which indicates that the most significant pH effect occurs on the surface. Topdressing containers with 40 g (1.41 oz.) of pulverized lime provided acceptable creeping woodsorrel control (>90%). In Experiment 5, incorporating the same lime rates used in Experiments 3 and 4 caused chlorosis and in some cases growth reduction in azalea and pieris while topdressed lime caused no change in growth or foliar color by 125 days after potting.
Pruning Leads to Increased Incidence of Freezing Damage in Abelia Hybrids
Authors: Chappell Matthew , Robacker Carol , Lindstrom Orville
Published: August 2020

North of USDA hardiness zone 7B, abelia suffers from freeze damage. Cultural factors may impact abelia's level of cold hardiness. To determine whether mid-season pruning affects the level of freeze damage, six abelia genotypes were tested in Griffin, GA. Plants were established in replicated field plots in 2001 and on July 3–4, 2003, half the individuals of each genotype were severely pruned. Laboratory freeze tests were conducted monthly on pruned and unpruned plants of each genotype from October 2003 to April 2004. Over the winter, all genotypes with exception of ‘Canyon Creek’ were significantly more cold tolerant in unpruned compared to pruned treatments. Analysis of each month independently revealed a significant difference among genotype-pruning treatment combinations from December 2003 to February 2004. Results for October and November 2003 and March and April 2004 were not significant due to an absence of cold hardiness. These results indicate that mid-season pruning of abelia may significantly reduce cold hardiness and lead to serious stem dieback in pruned plants.
Mineral N-content in the Substrate and N-uptake of Container Grown Shrubs
Authors: Bohne H. , Hasler M.
Published: August 2020

Three woody species Forsythia x intermedia ‘Lynwood’, Weigela ‘Bristol Ruby’, and Prunus laurocerasus ‘Otto Luyken’ were grown in 5 liter (# 1.3) containers with white peat and peat-reduced substrates. Plants were fertilized by a controlled-release or organic fertilizer. The aim was to investigate the relation between mineral N-content in the substrate and growth and N-uptake of the plants. Plant biomass was influenced by the mineral N-content in the substrate and by the substrate, but not by the type of fertilizer. Plant biomass of plants in the white peat substrate was significantly greater than plants grown in the peat-reduced substrates. Different equations describe the relation between mineral N in the substrate and biomass. Only for the white peat substrate in June and August was the slope of these regressions significant and the determination coefficient (r2) high. Dry matter of above ground biomass was 38% of fresh matter. The root-to-shoot ratio varied widely. There was a significant exponential relation between the biomass and the height of the plants, but not with the number of shoots. The N-content of the plant was related to its fresh matter. The findings establish a possibility to deduce N-uptake from plant biomass and thus improve fertilization.
Shasta Daisy Cultivars Respond Differently to Photoperiod and Vernalization
Authors: Coleman J.T. , Kessler J.R. , Keever G.J. , Sibley J.L.
Published: August 2020

Inconsistencies have been reported in the role of vernalization and photoperiod on growth and flowering of Leucanthemum x superbum Bergmans ex J. Ingram cultivars. Five cultivars were used to determine the effects of vernalization and photoperiod on days to flower, shoot height, growth index, flower shoot number, and quality rating. Plants received 0, 3, 6, 9, or 12 weeks of vernalization time (VER) at 4.4C (40F) and afterward were placed under either natural short days (SD) or night-interrupted lighting (NIL) in a greenhouse. ‘Becky’ showed an obligate requirement for NIL to flower with 100% of plants flowering under NIL and 0% of plants flowering under SD regardless of VER. Vernalization for 6 weeks before NIL increased shoot height, growth index, flower shoot number, and quality rating but the fewest days to flower occurred after 12 weeks of VER. ‘Silver Princess’, ‘Snow Cap’, ‘Snow Lady’, and ‘Summer Snowball’ showed a facultative requirement for NIL to flower. Plants under NIL flowered earlier, were larger, had more flower shoots, and had a higher overall quality rating than plants under SD. Shoot height and growth index were highest under NIL after 3 and 6 weeks of VER, flower shoot number was highest after 3 to 9 weeks of VER, but days to flower was least after 12 weeks of VER. Therefore, NIL after 3 or 6 weeks of VER would maximize plant size and quality for practical application in the cultivars studied but result in more DTF when compared to 12 weeks of VER.
Salinity and Growing Medium Regulate Growth, Morphology and Ion Uptake of Gaillardia aristata
Authors: Niu Genhua , Rodriguez Denise S. , Wang Yin-Tung
Published: August 2020

A study was conducted to characterize the response of Gaillardia aristata Pursh to salinity (0.8, 2.0 or 4.0 dS/m) and growing media: 100% perlite (Perlite), 100% Sunshine Mix No. 4 (Mix), 1 to 1 (by vol) perlite and Sunshine Mix No. 4 (Perlite Mix), or 1 to 1 Sunshine Mix No. 4 and composted mulch (Mix Mulch). Type of medium did not influence shoot dry weight (DW). However, root to shoot DW ratio was highest for plants grown in Perlite. Shoot DW of plants irrigated with tap water (0.8 dS/m) was higher compared to those irrigated with saline solution at 2.0 or 4.0 dS/m, except for those grown in Mix. Salinity did not alter the root to shoot DW ratio. In general, elevated salinity led to relatively short plants. Plants were taller when grown in Perlite or Mix Mulch with fewer lateral shoots compared to plants grown in Mix and Perlite Mix. Flower bud abortion occurred in plants grown in Mix or Perlite Mix, while this phenomenon was not observed in plants grown in Perlite or Mix Mulch. Overall, plants performed better in Perlite and Mix Mulch than Mix and Perlite Mix.
Effect of Substrate Depth and Planting Season on Sedum Plug Survival on Green Roofs
Authors: Getter Kristin L. , Bradley Rowe D.
Published: August 2020

Green roofs, a roofing technology that entails growing plants on rooftops, provide many benefits such as improved stormwater management, energy conservation, mitigation of the urban heat island effect, increased longevity of roofing membranes, reduction in noise and air pollution, and improved aesthetics. Plants on rooftops are more susceptible to extremes in temperature and drought due to their shallow substrate and elevation above ground. Because of these unfavorable growing conditions, plant selection and season of establishment are critical. The major objective of this study was to quantify the effect of substrate depth and planting season on successful establishment of plugs of Sedum species on green roofs. Plugs of nine species of Sedum were planted in East Lansing, MI, in autumn (September 20, 2004) or spring (June 8, 2005) and then evaluated for survival on June 1, 2005, and June 1, 2006, respectively. Overall, spring planting exhibited superior survival rates (81%) compared to autumn (23%) across substrate depths. Sedum cauticola ‘Lidakense’, S. floriferum, and S. sexangulare were not affected by season of planting. Sedum cauticola barely survived at any substrate depth or planting season, whereas the latter two exhibited nearly 100% survival regardless of planting season. All other species had superior survival percentages when planted during spring.
Effect of Backfill Composition on Post-Transplant Root Growth of Kalmia latifolia L.
Authors: Wright Amy N. , Wright Robert D. , Jackson Brian E. , Browder Jake F.
Published: August 2020

Post-transplant root growth is critical for landscape plant establishment. The Horhizotron™ provides a way to easily measure root growth in a wide range of rhizosphere conditions. Mountain laurel (Kalmia latifolia L.) plants were removed from their containers and planted in Horhizotrons in a greenhouse in Auburn, AL, and outdoors in Blacksburg, VA. Each Horhizotron contained four glass quadrants extending away from the root ball, and each quadrant within a Horhizotron was filled with a different substrate (treatment): 1) 100% pine bark (Pinus taeda L., PB), 2) 100% soil, 3) a mixture of 50:50 (by vol) PB:soil, or 4) 100% soil along the bottom of the quadrant to a depth of 10 cm (4 in) and 100% PB layered 10 cm (4 in) deep on top of the soil. Root growth along the glass panes of each quadrant was measured bi-weekly in Auburn and weekly in Blacksburg. In both locations, roots were longer in all treatments containing pine bark than in 100% soil. When pine bark was layered on top of soil, roots grew into the pine bark but did not grow into the soil. Results suggest that amending soil backfill with pine bark can increase post-transplant root growth of container-grown mountain laurel.
A Survey of the Depth of the Main Lateral Roots of Nursery Trees in Ohio Before and After Harvest
Authors: Rathjens Richard G. , Sydnor T. Davis , Gardner David S.
Published: August 2020

Deciduous trees in Ohio were surveyed before harvest (seven nurseries) and after harvest (eight brokerage facilities) to determine the depth of their main lateral roots. Main lateral roots originate at the root-shoot junction in trees and are also referred to as the root flare or buttress roots. In the nursery survey, differences in the depth of main lateral roots were found among nurseries and production year with main lateral roots an average of 6.1 cm (2.4 in) deep in the soil profile. From the broker survey, both brokers and propagation methods showed differences in depth with an average of 8.6 cm (3.4 in) of excess soil over the main lateral roots. The main lateral roots for most trees were greater than 2.5 cm (1 in) in depth which was deeper than industry standards allow.
Monitoring Effective Container Capacity: A Method for Reducing Over-Irrigation in Container Production Systems
Authors: Sammons Jonathan D. , Struve Daniel K.
Published: August 2020

A gravimetric substrate moisture monitoring system was used to control irrigation frequency and volume within a narrow range of substrate moisture contents to study the effects of reduced irrigation volume on growth and water use of baldcypress (Taxodium distichium L.). The four irrigation treatments were: control (daily scheduled irrigation at 16: 30 hours for 15 minutes or 6.75 liters (1.74 gal)/day) and 100, 80 and 60% of effective container capacity (ECC). Effective container capacity was defined as the maximum mass of a container, substrate and plant unit after gravitational water loss. Maintaining substrate moisture content at 80 and 60% ECC reduced baldcypress height, caliper, dry weight, and total plant N, P, and K content, but did not effect N, P or K concentrations compared to scheduled irrigation and 100% ECC treatments. Water use efficiencies (WUE, the volume of irrigation lost to evapo-transpiration divided by the total volume of irrigation applied) were determined for three dates. Plants under scheduled irrigation had WUEs of 17, 33, and 42% on July 8, July 24, and August 16, respectively. In contrast, WUE for plants under 100, 80 and 60% ECC treatments was 100% (no leachate) for the same dates. Plant water use under 80 and 60% ECC treatments was lower than that under scheduled and 100% ECC treatments. Plants under the 100% ECC treatment were 1.6 m (63 in) tall in August and used 2.6 liters (0.68 gal) of water per day. The gravimetric substrate monitoring system was an effective, plant-integrated method of reducing leachate volume that required minimal maintenance under the four month experimental period.
Pest Index: A New Approach to Establishing Thresholds for Pest Management in Woody Landscape Plants
Authors: Weston Paul A.
Published: August 2020

Pest index, a new approach to categorizing the threat posed by an organism to woody plants, is proposed to assist plant managers in establishing treatment thresholds for pests of woody plants. The need for such a tool is based on the incredible diversity of pests of woody plants and the lack of experimental data establishing such thresholds. The pest index is computed using information about the detectability, damage potential, and ease of control of various pest groups. Values of the pest index are proposed for a variety of pest groups, but can be readily adapted to other groups not considered (or modified for particular pests that differ significantly from others in the broad groupings listed here). Using the pest index should allow plant managers to deal effectively with pests that are likely to pose serious threats to trees and shrubs instead of simply applying pesticides whenever a pest is detected. Thus, the pest index should foster the adoption of integrated pest management (IPM) in ornamental settings.
Butter fly Feeding Preferences of Lantana camara Cultivars and Lantana montevidensis ‘Weeping Lavender’ in the Landscape and Nectar Characteristics
Authors: Bruner Laura L. , Eakes Donald J. , Keever Gary J. , Baier James W. , Whitman Celia Stuart , Knight Patricia R. , Altland James E. , Silva Erin M.
Published: August 2020

In landscape studies conducted in 2002 and 2003, Lantana camara (L.) ‘New Gold’ and ‘Radiation’ were visited by native butterflies to a greater extent than the remaining eight lantana in the studies. Other lantana visited preferentially but not as consistently included L. camara ‘White Doves’, ‘Firewagon’, ‘Confetti’, and Lantana montevidensis (Spreng.) ‘Weeping Lavender’. In general, the lowest visitation was experienced by L. camara ‘Cherry’ and ‘Carlos’. Total visit duration by one randomly selected butterfly was greater for ‘New Gold’, ‘Radiation’, ‘Firewagon’, and ‘White Doves’ than the remaining lantana. Plant characteristics including inflorescence number, number of flowers per inflorescence, percentage of yellow flowers per inflorescence, growth index, flower morphology, and flower color characteristics differed among cultivars. Cultivar differences that consistently correlated with visitation preferences were inflorescence number in 2002 and 2003, flower number per inflorescence in 2003, percentage of yellow flowers per inflorescence in 2002 and 2003, and growth index in 2003. Flower lightness and flower chroma correlated sporadically with visitation in late September and October 2002 and 2003. Percentage light reflectance of flowers for the wavelengths of green, yellow, orange, and red correlated with visitation in 2003. Based on correlation analysis, the cultivar characteristics that did not contribute to visitation differences included inflorescence width, corolla width, and corolla tube length.

In a separate study conducted in 2003 using the same lantana as in the visitation study, nectar volume, carbohydrate composition, and sucrose and fructose concentrations differed among inflorescences. Of ten Lantana evaluated, ‘Carlos’ and ‘Confetti had the largest inflorescence nectar volumes combined from nine flowers while ‘New Gold’, ‘White Doves’, and ‘Weeping Lavender’ had the smallest. The ratio of sucrose to hexose (fructose and glucose) in nectar from ‘Weeping Lavender’, ‘White Doves’, and ‘New Gold’ was greater than that of the remaining Lantana. The lowest ratios of sucrose to hexose were found for ‘Irene’, ‘Hot Country’, and ‘Carlos’, while similar to ‘Cherry’ and ‘Radiation’. The sucrose to hexose ratio for recently opened inner flowers was double that of middle and outer flowers. Sucrose and total sugar concentrations were greatest in recently opened inner flowers compared to middle and outer flowers. While direct comparison to the 2002 and 2003 studies of butterfly visitation preferences was not possible due to experimental design, data trends suggest a possible relationship between sugar composition, inflorescence nectar production and visitation from native butterfly species.
Interactive Effects of Pruning and Cyclanilide Application on Growth of Woody Nursery Crops
Authors: Holland A.S. , Keever G.J. , Kessler J.R. , Dane F.
Published: August 2020

A study was conducted to determine the effects of pruning on plant response to cyclanilide (CYC), a bioregulator that promotes lateral branching of fruit trees and selected woody nursery crops. In April 2004, non-pruned ‘Elizabeth Ann’ Japanese camellia (Camellia japonica L.) and small anisetree (Illicium parviflorum Michx. ex Vent.) received a single foliar application of 0, 25, 50, 100 or 200 ppm CYC, while the same species received a foliar spray of 0, 50 or 100 ppm CYC following uniform pruning. In June 2006, a single foliar application of 0, 100 or 200 ppm CYC was made to plants of ternstroemia (Ternstroemia gymnanthera Thunb.), ‘Sky Pencil’ holly (Ilex crenata Thunb.) and ‘Jennifer’ azalea (Rhododendron L.) that were either not pruned or uniformly pruned before CYC treatment. At 30 and 60 days after treatment (DAT), non-pruned, CYC-treated plants formed more shoots than pruned CYC-treated plants, however quality ratings at 120 DAT were generally higher in plants pruned prior to CYC treatment. In a third experiment, the effects of 200 ppm CYC on branching of ternstroemia, ‘Sky Pencil’ holly, ‘Jennifer’ azalea and ‘Snow White’ Indian hawthorn were ascertained when applied at three stages of lateral shoot development following pruning: immediately after pruning [developmental stage 1 (DS 1)], when new shoots were 1.3 to 2.6 cm (0.5 to 1 in) in length (DS 2), or when new shoots were 2.6 to 5.1 cm (1.0 to 2.0 in) in length (DS 3). At 60 days after pruning (DAP), shoot counts in ternstroemia and ‘Sky Pencil’ holly treated at DS 3 and ‘Snow White’ Indian hawthorn treated at DS 2 were greater than those of pruned controls. Shoot counts in ‘Jennifer’ azalea were not affected by plant developmental stage at the time of CYC application. Relatively minor injury was evident at 60 and 120 DAP in all species except ‘Jennifer’ azalea, and was most pronounced in ternstroemia and ‘Sky Pencil’ holly treated at DS 3 and in ‘Snow White’ Indian hawthorn treated at DS 2. Quality ratings were similarly high for plants of all species and treatments, except in ‘Sky Pencil’ holly in which quality ratings of plants treated with CYC at DS 1 or DS 3 were higher than those of pruned controls.
Paclobutrazol Soil Drenches Provide Partial Reductions in Symptoms of Apple Scab of Ornamental Trees and Guignardia Leaf Blotch of Horse Chestnut
Authors: Percival G.C.
Published: August 2020

A three year field trial was conducted using established apple (Malus cv. Crown Gold) and horse chestnut (Aesculus hippocastanum L.) to assess the efficacy of paclobutrazol (PBZ) root drenches against the foliar pathogens apple scab (Venturia inaequalis (Cooke) G. Wint.,) and Guignardia leaf blotch (Guignardia aesculi (Peck) VB Stewart). In the case of horse chestnut, pathogen severity of Guignardia leaf blotch was less (23–79%) in each of the three-year experimental periods in PBZ-treated trees compared to non-treated controls. Pathogen severity of apple scab was not affected during the first year after PBZ application; however, less (25–73%) disease severity was recorded in years 2 and 3 compared to non-PBZ treated controls. An increased PBZ concentration was associated with lower pathogen severity of both fungal pathogens. Irrespective of species, less pathogen severity in PBZ-treated trees was accompanied with greater leaf chlorophyll fluorescence (16–49%) values as measures of leaf photosynthetic efficiency. Marked differences in growth regulation between apple cv. Crown Gold (tolerant) and horse chestnut (sensitive) were recorded. PBZ applications resulted in less mean stem extension in both tree species but only reduced mean leaf size of horse chestnut. Based on the results of this investigation it is suggested that PBZ root drenches potentially offer a means of reducing the severity of apple scab and Guignardia leaf blotch for professionals involved with the nursery industry. However, where a zero pathogen control policy is required supplementary fungicide sprays would be needed. Similarly, the potential loss of aesthetics due to excessive growth regulation needs to be weighed against the benefits of pathogen protection and failure of PBZ to achieve total pathogen control may result in strong selection pressure for PBZ resistance in surviving populations.
Herbicide Use in Propagation of Loropetalum chinense ‘Ruby’
Authors: Cochran Diana R. , Gilliam Charles H. , Eakes Donald J. , Wehtje Glenn R. , Knight Patricia R.
Published: August 2020

Selected herbicides were evaluated during stem cutting propagation of Loropetalum chinense ‘Ruby’ to determine herbicide effects on rooting and subsequent plant growth. Herbicides evaluated were: Gallery (isoxaben), Ronstar (oxadiazon), or Regal O-O (oxyfluorfen + oxadiazon). Herbicides were applied as a single application during the propagation process: before sticking (BS), lightly rooted (LR), or fully rooted (FR). Before sticking treatments were applied to flats filled with standard medium prior to the cuttings being stuck. Once cuttings had roots 3 to 5 cm (1–2 in) long, the lightly rooted treatment was applied. Third stage of application (fully rooted) was applied once the cuttings were fully rooted. This study was repeated with the first study initiated on August 2, 2005, and the second study on September 22, 2005. Herbicides applied before sticking had the most impact on root growth. In the first study all cuttings treated with herbicides BS had less root coverage one year later than non-treated cuttings; however, shoot growth was not affected. In the second study, only Regal 0-0 reduced root coverage one year later; again, shoot growth was not affected. Cuttings treated with Gallery when lightly rooted or fully rooted were similar to non-treated cuttings one year later with both shoot and root growth. In general cutting response to Ronstar was similar to Gallery; however, Regal 0-0 tended to cause more growth suppression than Gallery or Ronstar regardless of the time of application.