bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen Nutrition of Containerized Ternstroemia gymnanthera
Authors: Conden Peter J. , Warren Stuart L. , Blazich Frank A.
Published: August 2020

Rooted stem cuttings of Japanese ternstroemia (Ternstroemia gymnanthera Thunb.) were grown in 3.8 liter (#1) plastic containers utilizing a substrate of pine bark: sand (8: 1 by vol) amended with micronutrients and dolomitic limestone. Plants were fertilized every other day with a solution consisting of P (K2H2PO4) at a constant rate of 30 mg/liter (ppm), K (K2SO4 and K2H2PO4) at a constant rate of 60 mg/liter (ppm), and a variable rate of N (NH4NO3) at 0, 10, 20, 40, 80, 160, or 320 mg/liter (ppm). Leaf area and shoot (stems and leaves) dry weight increased with increasing N application rate (NAR) until a plateau was reached at 117 mg/liter (ppm). Root: shoot ratio was 0.8 in non-fertilized plants, and decreased to ≈0.1 with N ≥ 104 mg/liter (ppm). Root dry weight and root area increased in response to increasing NARs, reaching a plateau with N at 86 and 70 mg/liter (ppm), respectively. Leaf weight ratio (leaf dry weight ÷ total plant dry weight) increased from 0.2 with N at 0 mg/liter (ppm) to a plateau of ≈0.6 with N ≥ 109 mg/liter (ppm). Stem weight ratio (stem dry weight ÷ total plant dry weight) was 0.4 with N at 0 mg/liter (ppm) then leveled off at ≈0.3 with N ≥ 52 mg/liter (ppm). Root weight ratio (root dry weight ÷ total plant dry weight) decreased steadily from 0.4 with N at 0 mg/liter (ppm) to ≈0.1 with N ≥ 117 mg/liter (ppm). Shoot N, P, K, and S concentrations increased with increasing NARs, reaching plateaus at 117, 23, 124, and 183 mg/liter (ppm), respectively, while Mg was unaffected by NAR. Calcium concentrations increased to 0.75% with a NAR of 40 mg/liter (ppm), and decreased to 0.6 % with N ≥ 107 mg/liter (ppm). Root mineral nutrient concentrations of N, P, K, and S increased with increasing NARs, reaching plateaus of 287, 53, 39, and 195 mg/liter (ppm) respectively, whereas Ca and Mg were not affected by NAR.
Modeling the Effectiveness of Bifenthrin for Reducing Populations of Japanese and Oriental Beetle Larvae in Nursery Containers
Authors: Cowles Richard S.
Published: August 2020

Preplant potting mix incorporation of Talstar 0.2G (bifenthrin) can prevent root weevil and white grub infestations in container-grown nursery crops. Analysis of bifenthrin residues from potting media aged under northern nursery conditions indicated that this insecticide has a half-life of at least 3 years, irrespective of medium composition. Dose-response tests of bifenthrin for controlling Japanese and oriental beetle larvae indicated that the LD50 for these species is approximately 1.1 and 1.7 parts per million (ppm), respectively. These data suggest that >95% larval mortality of these scarab species can be expected up to three years following treatment of media with 10 ppm bifenthrin, and >99.9% larval mortality is expected for at least three years following treatment of media with 20 ppm bifenthrin.
Effect of Cyclic Irrigation on Growth of Magnolias Produced Using Five In-ground Systems
Authors: Beeson R. C. , Keller K.
Published: August 2020

Five in-ground systems were evaluated based on shoot growth and marketability for the production of 2.17 m (7 ft) tall and 5.08 cm (2 in) trunk diameter Magnolia grandiflora cv. ‘Symmes Select’. Systems evaluated were Root Control Bags, Geo-Cell bags, and #25 containers in pot-in-pot in Experiment 1, and Agro-liners in socket pots and directly in-ground in Experiment 2. Each system was either cyclically irrigated or given a single irrigation event daily. In Experiment 1, cyclic irrigation increased the rate of height growth and trunk diameter compared to a single irrigation. Trees in Root Control Bags and pot-in-pot grew at a similar rate and faster than those in Geo-Cell bags. Faster growth rates with cyclic irrigation resulted in earlier marketability compared to single irrigation daily, except for pot-in-pot. In Experiment 2, cyclic irrigation increased the rate of trunk diameter growth, and Agro-liners in pots had greater height and trunk diameter growth rates than those directly in ground. Trees grown in the in-ground pot systems, whether in Agro-liners or black polyethylene containers, grew similarly to trees in Root Control Bags. Trees grown in Geo-cells or Agro-liners in-ground had significantly slower growth than the other treatments.
Time of Pruning Effects on Cold Hardiness of Butterfly Bush
Authors: Warr Jennifer C. , Keever Gary J. , Findley Douglas A. , Raymond Kessler J.
Published: August 2020

A study was conducted over a two-year period to determine how time of pruning affects cold hardiness of butterfly bush (Buddleia davidii (Franchet) ‘Royal Red’). Plants were pruned in November, January, or March, and pruned and non-pruned plants were exposed to six freezing temperatures two weeks after pruning treatments were applied. In addition, plants pruned in previous seasons were included in subsequent freezing treatments. Plants were rated for injury 2 or 3 weeks after treatment (WAT), and for mortality at 6 WAT. In fall 2001, at −6C (21.2F), injury ratings were higher in pruned than non-pruned plants. At all other treatment temperatures, injury to pruned and non-pruned plants was similar. In fall 2001, mortality increased with decreasing temperatures and was higher in pruned plants than in non-pruned controls, regardless of treatment temperature. In winter and spring 2002, injury and mortality increased with decreasing temperatures, but were not affected by pruning treatments. In fall 2002, temperature decreased as injury rating and mortality increased, regardless of pruning treatment and pruned plants had a higher injury rating and mortality than non-pruned across all temperatures. In winter 2003, injury rating and mortality increased with decreasing temperatures and pruning did not affect either. Spring 2003 plants, which had deacclimated prior to freeze treatment, were not affected by pruning or freezing treatments.
Artillery Fungus Sporulation on 27 Different Mulches — A Field Study
Authors: Davis Donald D. , Kuhns Larry J. , Akina Kristen , Harpster T. L.
Published: August 2020

During the last decade, the ‘artillery fungus’ has emerged from an interesting mycological curiosity that grows in landscape mulch to a problem of major financial concern to homeowners, insurance companies, mulch producers, and landscape contractors. This common inhabitant of landscape mulch produces sticky spore masses (gleba) that it shoots towards the light or towards reflective objects such as light-colored automobiles or house siding. We evaluated 27 different mulches in the field to determine their ability to support growth and sporulation of the artillery fungus. Each mulch type was inoculated in 1998 with the artillery fungus and the amount of sporulation (number of spore masses on targets) determined annually until 2002, approximately 4 years after inoculation. We grouped the 27 mulches into nine general categories that had common characteristics: mulches that originated from large piles of bark and wood mixtures, mulches blended with 5% compost, cedar mulch, mulches commercially designated as ‘bark’ but containing considerable wood, dyed wood chips, non-dyed wood chips, cypress mulch, large bark nuggets, and 100% spent mushroom substrate. The mulches obtained from large piles shredded blends of bark and wood supported significantly greater levels of artillery fungus sporulation than did other mulches. Such highly susceptible mulches should be avoided if the artillery fungus is to be minimized. In contrast, large bark nuggets, cypress mulch, and 100% spent mushroom substrate supported less artillery fungus. Other mulches supported intermediate levels of sporulation. All wood/bark landscape mulches will eventually support the artillery fungus over extended time periods (i.e., 34 years), and even more tolerant mulches should be replaced or covered with a fresh layer of mulch on a regular basis.
Assessing the Infectivity of Commercial Mycorrhizal Inoculants in Plant Nursery Conditions
Authors: Corkidi Lea , Allen Edith B. , Merhaut Donald , Allen Michael F. , Downer James , Bohn Jeff , Evans Mike
Published: August 2020

The infectivity of ten commercial mycorrhizal inoculants was examined in nursery conditions. Corn plants were grown in a soil-based medium and in two different soilless substrates, a potting mix prepared with redwood bark, pine sawdust, calcined clay and sand, and the commercial Sunshine #5 mix, mainly composed of Canadian sphagnum peat moss. The percentage of mycorrhizal colonization obtained with the different mycorrhizal inoculants ranged from 0 to 50%. This variation might reflect the presence or absence of viable propagules, the difference in the recommended rates applied as well as the difference in the content and type of infective propagules of each product. However, the infectivity of each mycorrhizal inoculant was also influenced by the growing media. Two products promoted higher values of mycorrhizal colonization in the Sunshine mix, three in the nursery mix and one in the soil-based medium. Mycorrhizal colonization did not enhance plant growth. Only the plants inoculated with the products that did not promote mycorrhizal colonization increased their growth relative to the non-inoculated controls, suggesting the presence of other growth promoters in the inoculum products. Based on these results, nurseries should conduct preliminary tests to determine which inoculants will perform in their potting mixes to assure the best fit of inoculum with their particular conditions.
Effects of Magnesium-Sulfate on Leaf Chlorosis, Plant Growth and Nutrient Uptake in Camellia sasanqua ‘Shishi Gashira’
Authors: Merhaut Donald J.
Published: August 2020

A ‘V’-pattemed chlorosis of older leaves is frequently observed on specific cultivars of container-grown Camellia sasanqua. Symptoms are expressed during the flowering period and as the first vegetative flush of the season develops in early spring. Symptomatic leaves eventually senesce and subsequent vegetative flushes appear healthy. In the following study, container-grown Camellia sasanqua ‘Shishi Gashira’ were fertilized with 500 ml of nutrient solution containing one of five treatments: 0.0, 4.0, 10, 20, or 40 g/liter magnesium sulfate heptahydrate (MgSO4·7H2O) per 19-liter container every two weeks for nine months to determine if chlorosis could be prevented. Nutrient analyses were conducted on all plant organs to determine if there was a correlation between nutrient partitioning to different organs and the expression of leaf chlorosis. Supplemental MgSO4·7H2O fertilization increased the Mg concentration in the roots, stems, leaves and flowers, and increased the sulfur concentration only in the leaves and stems. Calcium concentration in all organs decreased and potassium concentration in the leaves and stems decreased with increased fertilization rates. Fertilization with MgSO4·7H2O prevented the development of ‘V’-patterned chlorosis but did not affect plant dry weight.
Auxins and Water-Retaining Polymer Root Dips Affect Survival and Growth of Newly Transplanted Bare-Rooted European Beech and Silver Birch
Authors: Percival G.C. , Barnes S.
Published: August 2020

The influence of two commercially available auxin products (IBA talc, IBA:NAA solution) in combination with a water-retaining polymer applied to the root system of two transplant-sensitive tree species, silver birch (Betula pendula Roth.) and beech (Fagus sylvatica L.) under field conditions was investigated. The efficacy of the auxins on growth was quantified by recording root and shoot growth and survival rates at week 8 and 20 after bud break. Improvements in tree vitality were assessed by measurement of leaf photosynthetic rates, chlorophyll fluorescence and chlorophyll content. Application of an IBA talc improved growth and vitality of beech but had little beneficial effects on birch. A combination of liquid IBA:NAA (50:1 dilution) and a water-retaining polymer at transplanting proved most effective for root regeneration, growth and tree vitality of both species compared to other treatments. Regardless of species, applications of a water-retaining polymer alone had no significant effect on tree survival rates or tree vitality. However, growth of birch was significantly reduced compared to controls indicating a detrimental effect of polymer application alone on this species. Results show that commercially available auxin products in combination with a water-retaining polymer can be used to reduce transplant losses and improve tree vitality and growth over a growing season in two difficult-to-transplant species. Selection of an appropriate auxin(s), however, is important as effects on growth and vitality can vary between tree species.
Establishment and Persistence of Field Sown North American Prairie Grasses in Southern England in Response to Mulching and Extensive Weed Management
Authors: Hitchmough James , Reid Emily , Dourado Anna
Published: August 2020

Establishment and management of North American prairie grasses by field sowing was investigated at the Royal Horticultural Society Garden at Wisley, Surrey, in Southern England. Untreated seed of little bluestem (Schizachyrium scoparium (Michx.) Nash); indian grass (Sorghastrum nutans (L.) Nash); and prairie dropseed (Sporobolus heterolepis (A.Gray) A.Gray.) was sown in May 1997 at 550 seeds/m2 onto topsoil plots (control), topsoil with charcoal mulch, and topsoil covered with transparent, perforated crop polyethylene post sowing. Highest percentage emergence was recorded in the clear polyethylene mulch followed by the charcoal mulch. Weed competition was managed by cutting to 75 mm (≅ 3 in) above the soil surface. Dry weight of prairie grass seedlings in October 1997 was strongly negatively correlated with percentage weed cover in June 1997. Despite the weed competition, on plots where sufficient seedlings survived, Schizachyrium and Sorghastrum were eventually able to dominate Agrostis stolonifera, the most abundant weed, when burnt annually in April. No regeneration of prairie grasses from self-sown seed was observed within the experimental treatments over an 8 year period. The application of this research to more sustainable horticultural practice in urban landscapes is discussed.
Monolithic Slag as a Substrate for Rooting and Bare- Rooting Stem Cuttings
Authors: Blythe Eugene K. , Sibley Jeff L. , Tilt Ken M. , Zinner Bertram
Published: August 2020

Stem cuttings of Hydrangea paniculata Sieb., Rosa L. ‘Red Cascade’, Salvia leucantha Cav., and Solenostemon scutellarioides (L.) Codd ‘Roseo’ were inserted into six rooting substrates: monolithic slag, sand, perlite, vermiculite, Fafard 3B, or fine pine bark. Rooting, initial shoot growth, and ease of dislodging substrate particles from root systems upon bare-rooting by shaking and washing cuttings rooted in monolithic slag were compared to cuttings rooted in the five other substrates. Rooting percentage, number of primary roots per rooted cutting, and total root length per rooted cutting for cuttings rooted in monolithic slag were generally similar to the five other substrates. Particles of monolithic slag were dislodged more readily from root systems by shaking than were the other substrates. Gentle washing removed almost all particles of monolithic slag and sand from the root systems of all taxa and removed almost all particles of pine bark from all taxa except S. scutellarioides ‘Roseo’. Monolithic slag had a bulk density similar to sand, retained less water than the other substrates, and was similar to perlite, vermiculite, and pine bark in particle size distribution.
Container Size and Initial Trunk Diameter Effects Growth of Acer rubrum L. During Production
Authors: Fare Donna C.
Published: August 2020

Two studies were conducted to determine container size and liner (young bare root trees) trunk diameter effects on growth of Acer rubrum L. ‘Franksred’, Red Sunset™ red maple. In experiment 1, maples liners with initial mean trunk diameters of 12.2 mm (0.5 in), 15.9 mm (0.6 in), and 22.3 mm (0.9 in) were potted in 26.5 liter (#7), 37.8 liter (#10), and 56.8 liter (#15) containers and grown for 18 months (2 growing seasons). Height and trunk diameter growth at the end of each growing season were affected by both the initial liner trunk diameter and container size. During year 1, liners with an initial trunk diameter of 12.2 mm (0.5 in) increased 28 and 70% more in height growth compared to liners initially 15.9 mm (0.6 in) and 22.3 mm (0.9) in trunk diameter, respectively. Twenty three percent more height growth occurred with maples in 37.8 liter (#10) and 56.8 liter (#15) containers compared to those in 26.5 liter (#7) containers. Trunk diameter growth increased 50% more with 12.2 mm (0.5 in) liners compared to 22.3 mm (0.9 in) liners. A 25% increase in trunk diameter growth occurred with liners potted in 56.8 liter (#15) compared to 26.5 liter (#7) containers. At the end of the second growing season, final tree size was similar with liners that were initially 12.2 mm (0.5 in) and 15.9 mm (0.6 in) liners in trunk diameter to those initially 22.3 mm (0.9 in) when potted into 37.8 liter (#10) and 56.8 liter (#15) containers. In experiment 2, maple liners with trunk diameters 17.5 mm (0.7 in), 20.5 mm (0.8 in), and 29.0 mm (1.1 in) were potted in container sizes 26.5 liter (#7), 37.8 liter (#10), and 56.8 liter (#15) and grown for 18 months (2 growing seasons). Liners grown in 56.8 liter (#15) containers had 92% more height growth and 48% more trunk diameter growth than with liners in 26.5 liter (#7) containers. At termination, the shoot dry weight was 41% larger with maples in 56.8 liter (#15) containers compared to those grown in 26.5 liter (#7) containers.
Growth and Flowering Response of Container Grown Passion Flower Cultivars to Fertilizer and Paclobutrazo
Authors: Berberich Stephen , Snyder John , Geneve Robert , Williams Mark A.
Published: August 2020

The effects of fertilizer and paclobutrazol applications on growth and flowering in four container grown passion flower cultivars (Passiflora ‘Amethyst’, Passiflora ‘Blue Bouquet’, Passflora ‘Fledermouse’, and Passflora ‘Lady Margaret’) were evaluated. A four month production system was used that included propagating cuttings in late winter, followed by greenhouse liner production in early spring, and finally by two months of outdoor container production. Shoot growth was increased by increasing fertilizer rates and the response was highly cultivar dependent. Fertilizer rates resulting in the highest levels of growth for each cultivar were generally higher than those required for most container grown nursery crops, ranging between 3.2 and 5.3 g/liter (0.44 and 0.73 oz/gal) of Osmocote 14N–6.0P–11.6K (14–14–14). Paclobutrazol reduced overall plant size without increasing the number of nodes or flowers. Cultivars were chosen based on cold tolerance and vigor and cultivar appeared to be the most significant independent variable. Of the cultivars evaluated ‘Lady Margaret’ was most suitable for the four month production system.
Consumer Purchasing Habits of Environmental Horticulture Products in Florida
Authors: Satterthwaite Loretta N. , Haydu John J. , Hodges Alan W.
Published: August 2020

A garden center exit survey examining consumer purchasing habits of environmental horticulture products was conducted in Florida in 2002. A total of 910 surveys were completed with information on why a particular store was chosen for shopping, the items planned for purchase and whether or not the final purchase matched the intentions of the buyer. Convenience/location was the most important reason for shopping at a particular store, followed by price, quality, service, information and miscellaneous other reasons. Most respondents were shopping for non-plant (hardgood) items, but when shopping for plants, flowering plants for the outdoors were the most sought after. Seasonal shopping habits were identified with nearly every respondent shopping at least once during the spring and fewer respondents shopping at least once during each of the other seasons. Information was also collected on gender, age, education level, and annual income of respondents, as well as location and type of store (chain or independent). Respondents who reported having college level education, an annual income greater than $50,000 or were shopping at an independent garden center, also indicated convenience/location as their primary reason for selecting a particular garden center; however, unlike other respondents, price was not their second reason for shopping at a particular store.
Rooting Softwood Cuttings of Leyland Cypress Outdoors Under Shade
Authors: Hinesley L. Eric , Blazich Frank A. , Derby Scott A.
Published: August 2020

Stem cuttings of Leyland cypress [x Cupressocyparis leylandii (A.B. Jacks. & Dallim.) Dallim. & A.B. Jacks], were rooted to determine the effect of A) date of collection, rooting substrate, and mist frequency, B) auxin formulation and concentration, C) rooting substrate, D) substrate fertility, and E) type of cutting and auxin concentration. Results were best for misting intervals of 5 to 7 min during the day, but 10 min was also adequate. Rooting was comparable for softwood cuttings collected in late May or late June. Powder and liquid auxin formulations, which both contained indolebutyric acid (IBA), yielded similar results. Cuttings that were more lignified (light tan color) at the bases benefited the most from higher concentrations [≈ 8000 ppm (0.8%)] of IBA in talc, whereas less mature cuttings (green at the bases) rooted in highest percentages with lower concentrations [≈ 3000 ppm (0.3%)]. Rooting was similar in substrates with a peat:perlite ratio (v/v) of 1:1, 1:2, or 1:4, whereas results were less satisfactory in 100% perlite. Controlled release fertilizer [1.8 kg/m3 (4 lb/yd3)] in the rooting substrate did not affect rooting percent, but greatly increased root mass and quality of rooted cuttings. Doubling the rate resulted in little additional improvement. Rooting was comparable for vigorous side shoots (1st-order laterals) and tips from vigorous upright branches (primary axes) of similar maturity.
Cold Hardiness of the Rare Dirca occidentalis: Comparisons to Dirca palustris from Disparate Provenances
Authors: Graves William R. , Schrader James A. , Sharma Jyotsna
Published: August 2020

We determined the cold hardiness of Dirca occidentalis (western leatherwood) within its restricted natural distribution in northern California and made comparisons to Dirca palustris (eastern leatherwood) from northern (Iowa) and southern (Florida) provenances. Stems of western leatherwood were sampled twice while all or some plants were dormant (October 27 and December 8, 2004, respectively) and again on January 19, 2005, when flowering and incipient vegetative shoot growth of most plants had begun. Stems of D. palustris were sampled on the same schedule and on March 2, 2005 (Iowa and Florida) and April 13, 2005 (Iowa) such that the last sampling date coincided with flowering and incipient vegetative shoot growth. Lowest survival temperature was determined based on visual assessments of the viability of cambium and phloem of stems exposed to progressively lower temperatures in a freezer. Lowest survival temperature of western leatherwood was −6 to −3C (21 to 27F) regardless of date. Eastern leatherwood accrued hardiness through mid-winter and then deacclimated; minimal lowest survival temperature of eastern leatherwood was −33C (−27F) in Iowa and −17C (1F) in Florida. The minimal cold hardiness of western leatherwood is consistent with its natural distribution in specialized niches within a Mediterranean climate. Unless western leatherwood accrues increased hardiness when planted where winters are harsh, its horticultural use will be restricted to areas with mild winters. In contrast, widespread use of eastern leatherwood is feasible if production challenges are resolved and selections from climatically appropriate provenances are used.
Pruning Lower Branches of Live Oak (Quercus virginiana Mill.) Cultivars and Seedlings during Nursery Production: Balancing Growth and Efficiency
Authors: Gilman Edward F. , Anderson Patti J. , Harchick Christopher
Published: August 2020

Tree production requires time for pruning to meet customer expectations, yet pruning can slow growth and increase the time (and cost) to prepare trees for market. Our research quantifies trade-offs between growth and pruning. In two separate locations, over two time periods, we found no difference in caliper growth between trees with only the largest one or two low branches removed at each pruning, compared with trees having all lower branches shortened. Acorn-propagated and Cathedral Oak® Quercus virginiana (Mill.) with all branches removed from the lower 1.37 m (4.5 ft) of trunk (temporary branches destined to be removed to produce a trunk clear of branches and a distinct canopy) by 18 months after planting had smaller caliper than other pruning treatments; however, pruning these branches had no impact on the Highrise® cultivar. Removing the largest one or two low branches at each pruning was the most efficient pruning method tested. Removing all temporary branches in February of the last year of production (2004) did not reduce caliper, height, or canopy spread compared to removing half in February and half in October. Since there was no difference in time required for pruning, we suggest removing branches early in the last growing season for more completely closed wounds and enhanced customer appeal.
Nursery Production of Helleborus x hybridus: Management of Nitrogen and Substrate pH
Authors: Kraus Helen T. , Warren Stuart L.
Published: August 2020

One-year-old seedlings of Helleborus x hybridus Hort. Ex Vilmorin (Lenten rose) were potted into 3.8 liter (#1) containers filled with a pine bark substrate amended with one of five rates of dolomitic limestone [0, 1.4, 2.7, 4.1, or 5.4 kg/m3 (0, 3, 6, 9, or 12 lb/yd3)]. Substrate pH responded quadratically with increasing rate of dolomitic limestone (DL) producing a range of substrate pH from 4.5 to 6.9. Nitrogen application rates (NARs) ranging from 10, 20, 40, 80, and 160 mg/liter were applied with every irrigation. Top dry weight was affected by NAR, DL, and NAR × DL rate interaction. When no DL was added to the substrate, top dry weight increased quadratically with increasing NARs with maximum dry weight occurring with N at 124 mg/liter. However, when the substrate was amended with DL at 1.4, 2.7, 4.1, or 5.4 kg/m3 (3, 6, 9, and 12 lb/yd3) top dry weight increased linearly with increasing NARs with maximum top dry weight of 15 g to 16 g (0.53 oz and 0.56 oz) occurring with N at 160 mg/liter. Contrast analysis comparing DL rates within each NAR revealed DL rates of 1.4, 2.7, 4.1, and 5.4 kg/m3 (3, 6, 9, and 12 lb/yd3) produced greater top growth compared to growth at the DL rate of 0 kg/m3 (0 lb/yd3) at NARs of 40, 80, and 160 mg/liter. Furthermore, when fertilized with N at 40, 80 or 160 mg/liter, top dry weight produced with DL rates of 1.4, 2.7, 4.1, and 5.4 kg/m3 (3, 6, 9, and 12 lb/yd3) did not differ within each NAR. Root dry weight was unaffected by NARs and NAR × DL rate interaction. Rate of DL affected root dry weight with the largest increase in root growth occurring with DL between 0 kg/m3 and 1.4 kg/m3 (0 lb/yd3 and 3 lb/yd3). Root-to-top ratio (RTR) responded quadratically with increasing NAR with the lowest RTR occurring with N at 140 mg/liter. Foliar N, P, K, Ca, Mg, S, and Fe concentrations were unaffected by rate of DL and NAR × DL rate, whereas foliar N, P, K, Ca, Mg, and S were affected by NARs. Foliar N, P, K, and S concentrations responded quadratically to increasing NARs; foliar Ca and Mg concentrations were linear; and foliar Fe concentration was unaffected by NARs.
Establishment and Growth of Begonias in the Landscape as Affected by Root Ball Condition at Transplanting
Authors: Scheiber S.M. , Beeson Richard C.
Published: August 2020

Begonias (Begonia semperflorens) were transplanted into an open-sided clear polyethylene covered shelter to evaluate the effect of root ball condition on establishment and growth. Three root ball classes were evaluated: non root-bound (NRB; 6 week old plants), root-bound (RB; 10 week old plants), and root-bound with the bottom 1 cm of the root ball removed (RBM). Non root-bound plants had greater growth rates for both height and faster rates of accumulation for cumulative root dry mass and new root dry mass relative to the other treatments tested. Cumulative shoot dry mass, new shoot dry mass, and total biomass accumulation rates were slower among RB plants compared to other rootball conditions. Mean canopy size, shoot dry mass, and biomass of NRB were significantly less at transplant; however all parameters were comparable among treatments 12 weeks later. Final mean shoot to root ratios were lower for the NRB treatment relative to RBM. Results indicate smaller, NRB transplants establish faster in the landscape. Furthermore, rootball manipulation is not recommended as it had no significant effect on root establishment or canopy growth of this annual bedding plant in the landscape.
Postemergence Liverwort Control in Container-Grown Nursery Crops
Authors: Newby Adam , Altland James E. , Gilliam Charles H. , Wehtje Glenn
Published: August 2020

Four experiments were conducted in Aurora, OR, and Auburn, AL, to evaluate effectiveness of herbicides for postemergence liverwort control. A sprayable herbicide, quinoclamine (Gentry 25-WP), was applied at rates between 1.8 and 7.6 kg ai/ha (1.6 and 6.8 lb ai/A), with or without a surfactant, and in spray volumes of 1019 or 2037 liters/ha (109 or 218 gal/A). Across all experiments, postemergence liverwort control was good (>90%) at the lowest rate when liverwort infestation was light (liverwort covered ≤25% of the substrate surface with no sporocarps). When liverwort infestation was high (liverwort covered ≥60% of the substrate surface with some sporocarps present), or in conditions favorable to liverwort growth, control improved by using higher rates or including a surfactant. At the highest labeled rate (7.6 kg ai/ha (6.8 lb ai/A)), postemergence liverwort control up to 14 days after applications was 96 to 100% across all four experiments. Long-term liverwort control through 42 to 56 days after application varied depending on the location and time year, with control decreasing as environmental conditions allowed for increased liverwort vigor. Sodium carbonate peroxyhydrate (TerraCyte) provided poor to moderate control, and was largely dependent on liverwort vigor. Flumioxazin (BroadStar) provided unacceptable postemergence control across all experiments.
Seasonal Biomass and Nitrogen Accumulation of Rosa ‘Mariandel®’ Grown in Compost Amended Peat at Different Fertilization Rates
Authors: Amha Yosef , Bohne Heike
Published: August 2020

The growth and nitrogen (N) uptake of Rosa ‘Mariandel®’ were evaluated at four fertilization rates: 0, 0.4, 0.8 and 1.2 g N/liter (0, 0.016, 0.032 and 0.048 oz/qt). Plants were harvested at 6-week intervals. New shoots in all treatments retained the highest relative dry weight percentage, apparently at the expense of root. The total N concentration, content, and uptake at 12 and 18 weeks, but not at 6 weeks, after potting were significantly (r2 > 0.59; P = 0.0005) affected by rates of fertilization. Although DM in the old shoots of all treatments slightly increased over the first 6 weeks, the corresponding N content decreased due to translocation. Except in old shoots, a significant linear trend occurred between DM accumulation and N content but not with N concentration (at least up to 12 weeks). However, N concentration in most plant parts was significantly (P < 0.05) correlated with the respective N content. Excluding N released from the substrate, plants in 0.4, 0.8 and 1.2 g N/liter treated pots received 80, 126 and 182 mg (0.003, 0.004 and 0.006 oz) N per week, respectively, as used Osmocote (15N–4P–7.5K–1.8Mg) showed a linear (r2 > 0.99) N-releasing rate. The corresponding total mineralized N in each control pot was 96 mg (0.003 oz) and 140 mg (0.005 oz) over the first and the second 6-week interval. Overall, ‘Mariandel®’ grown in 0.8 and 1.2 g N/liter treated pots had the highest mean N concentration and content respectively.
Plant Growth Retardants Affect Growth and Flowering of Achillea × ‘Coronation Gold’
Authors: Kessler J.R. , Keever G.J.
Published: August 2020

An experiment was conducted to determine the effects of several widely used plant growth retardants on plant size and flowering of Achillea × ‘Coronation Gold’. Plants in 10 cm (4 in) pots were grown in a greenhouse and treated with B-Nine at 0, 2550, 5100, or 7650 ppm; Cycocel at 0, 767, 1534, or 2301 ppm; B-Nine/Cycocel at 0, 1275/1534, 2550/1534, or 3825/1534 ppm; Sumagic at 0, 11, 22, 33, 44, or 55 ppm; Bonzi at 0, 32, 64, 96, 128, or 160 ppm; or Cutless at 0, 40, 80, or 120 ppm as a spray 1 week after vernalization. B-Nine, Cycocel, B-Nine/Cycocel, Sumagic, Bonzi, and Cutless reduced shoot height and growth index by 36 and 26%, 39 and 27%, 61 and 41%, 75 and 52%, 52 and 36%, and 75 and 51%, respectively, with the highest rate of each. B-Nine, Cycocel, B-Nine/Cycocel, and Sumagic, but not Bonzi or Cutless, increased the number of days to open inflorescence by 3-5 days with increasing rate. Sumagic, Bonzi, and Cutless reduced inflorescence diameter by up to 15, 18, and 14%, respectively but not B-Nine, Cycocel, or B-Nine/Cycocel. The highest quality ratings of 2.8 to 3.0 were found with B-Nine/Cycocel at 3825/1534 ppm, Sumagic at 22 and 33 ppm, and Bonzi at 64 ppm. Differences between the results in this study and earlier studies implicate the possible impact of differences in experimental environments, container size, or stage of development when the plant growth retardant treatments were applied.
Weed Control and Phytotoxicity Following Preemergence Herbicide Applications to Container-grown Herbaceous Plants
Authors: Klett James E. , Staats David , Howlett Teri , Rogoyski Matthew
Published: August 2020

Effectiveness of five preemergence herbicides was determined for four container-grown ornamental crops. Herbicides tested were Barricade (prodiamine); BroadStar (flumioxazin); Gallery (isoxaben); Scotts Ornamental Weedgrass Control (Scotts OWC) (pendimethalin); and Treflan (trifluralin). Four herbaceous plant species were utilized in this trial, namely, Guizhou sage (Artemisia lactiflora Wall. (Guizhou group)); hopflower oregano (Origanum libanoticum Boiss.); Daghestan sage (Salvia daghestanica Sosn.); and skullcap (Scutellaria resinosa Torr.). The seven weed species evaluated in this trial were annual bluegrass (Poa annua L.); barnyardgrass (Echinochloa crus-galli L.); yellow foxtail grass (Setaria glauca L.); purslane (Portulaca oleracea L.); common groundsel (Senecio vulgaris L.); redroot pigweed (Amaranthus retroflexus L.); and annual sowthistle (Sonchus oleraceus L.). Two controls, one with weeds and one without were also evaluated. The experiment was conducted in two locations: Fort Collins and Grand Junction, Colorado. Weed control levels varied across a range of herbicide treatments and ornamental species. Where differences among herbicides were observed, BroadStar and Treflan tended to be more effective than the other herbicides, while Gallery, Scotts OWC and Barricade, were less effective. Plants treated with Gallery often resulted in decreased dry weights; however, no visual phytotoxicity symptoms were observed with any herbicide treatments. Daghestan sage and skullcap were the crop species most adversely effected.
Growing Blackgum Whips in Ground Beds Increases Survival and Growth Following Transplanting to Field
Authors: Struve Daniel K.
Published: August 2020

Difficult-to-transplant species can be produced in containers and transplanted with high survival. However, circling roots can develop even in containers designed to prevent root malformation, requiring root pruning before transplanting and this results in transplant shock. In order to determine the effect of different containers and substrates on whip growth and survival after transplanting, blackgum (Nyssa sylvatica Marsh.) whips were grown in four container types (Spinout®-treated plastic, tall or short fiber containers or in ground beds) and two substrates (pine bark: Com-Til™ and Haydite: Com-Til™). Container-grown whips were overwintered in unheated polyhouses; bed-grown were overwintered out-of-doors with no winter protection. Two year branched whips grown in Haydite: Com-Til™ were bare rooted and root pruned before transplanting. Whips grown in containers required root pruning to correct root malformation, while whips grown in pine bark: Com-Til™ in ground beds were root pruned as part of the harvesting process. Container and substrate treatment did not affect whip stem diameter, but whips grown in ground beds in pine bark: Com-Til™ were the tallest. Overwinter survival for container-grown whips ranged from 77 to 88% and averaged 85% for whips grown in ground beds. The percentage of whips reaching 1.2 m in height ranged from 53 to 97% for whips produced in tall fiber containers in Haydite: Com-Til™ substrate and in short fiber containers in Haydite: Com-Til™ substrate, respectively. Two years after whips were transplanted, survival averaged 98% (174 of 178). Two years after transplanting, whips produced in beds in pine bark: Com-Til™ substrate had the greatest caliper. Whips produced in ground beds in pine bark: Com-Til™ offer an acceptable alternative to container-produced blackgum whips; they had high overwintering and transplant survival; they were taller at the end of the two year whip production period, and two years after transplanting to field plots they had the largest trunk caliper.
Growth of Moonshine Yarrow on a Limited Moisture Budget
Authors: Khalil Shad Khan , St. Hilaire Rolston , O’ Connell Mary , Mexal John
Published: August 2020

Yarrow is an herbaceous perennial that is highly recommended for landscape gardens in many parts of the United States. However, performance data of yarrow produced under limited irrigation conditions is lacking. During 2004 and 2005, we studied the growth and physiology of yarrow (Achillea ‘Moonshine’) maintained as well irrigated controls or irrigated when there was a 30 or 60% depletion of moisture in the growing substrate. Plants irrigated at the 60% moisture level had the lowest predawn water potential, stomatal conductance and transpiration rate. Cell osmotic potential and relative water content data suggest that yarrow might be able to withstand prolonged exposure to drought. In 2005, net assimilation rate of well irrigated plants (0.317 mg/cm2/d) was almost twice as high (0.179 mg/cm2/d) as that of plants maintained at the 60% moisture level. This suggests that a 60% moisture depletion level had a very significant impact on carbon assimilation. In 2005, leaf area of plants irrigated at the 30% moisture depletion level showed only a 15% decline compared to well irrigated plants, while those irrigated at the 60% moisture depletion level showed a 47% decline in leaf area.
Planting Depth in Containers Affects Root Form and Tree Quality
Authors: Gilman Edward F. , Harchick Chris
Published: August 2020

After 40 months in air root pruning containers, Quercus virginiana ‘SDLN’ Cathedral Oak® live oak planted 3.8 and 8.9 cm (1.5 and 3.5 in) deep from rooted cuttings had greater caliper than trees planted at 1.3 cm (0.5 in) below substrate surface. Trees in the 1.3 cm (0.5 in) deep treatment grew taller than all other trees except for those in the 3.8 cm (1.5 in) deep treatment. Most (80%) trees were graded as culls according to root evaluations in the Florida Grades and Standards for Nursery Stock. This resulted mostly from roots circling and crossing the top of the root ball in the #3 and/or #15 container sizes. Trees planted 6.4 cm (2.5 in) deep in #3s, then 6.4 cm deep in #15s, and 6.4 cm deep in #45s [19 cm (7.5 in) total depth] had fewer, smaller diameter, and deeper primary roots than trees planted at all other depths. The presence of a trunk flare and surface roots decreased with increasing planting depth indicating that these could be used as an indicator of primary root depth. Cathedral Oak® demonstrated the capacity to generate new roots above the primary flare roots only when rooted cuttings were planted into #3 containers. Trees adjusted their root systems by generating a new set of roots along the buried stem up to the substrate surface. Roots did not grow from the buried portion of the stem when trees in #3 containers were planted 6.4 cm (2.5 in) deep into #15 containers. In other words 75% or more of the primary structural roots were deflected by either the #3 or #15 container wall or both, indicating that most primary roots that emerged from the trunk did so when the tree was in the #3 or #15 container within 22 months of planting from rooted cuttings. Roots often grafted when crossed or laid against other roots, but roots did not graft to trunks.
Flowering, Fecundity, Seed Germination, and Seed Viability of Viburnum opulus L. Cultivars
Authors: Conklin Janine R. , Sellmer James C.
Published: August 2020

Mature specimens of Viburnum opulus and cultivars ‘Leonard's Dwarf’ and ‘Roseum’ were assessed over 2 years for flower and seed production, seed germination, and seed viability as determined by a tetrazolium test to understand their invasive potential. ‘Aureum’, ‘Compactum’, ‘Losely's Compact’, ‘Nanum’, and ‘Xanthocarpum’ were also tested for germination and viability of seeds. Cultivars differed in flower and seed production, seed germination, and seed viability. ‘Roseum’ prolifically produced highly viable seed that germinated at moderate rates under greenhouse conditions (8,354, 100%, and 73%, respectively). Viburnum opulus and ‘Leonard's Dwarf’ produced fewer viable seed which showed moderate to low germination rates (609, 100%, and 53%; 712, 100%, and 5%, respectively). ‘Aureum’ and ‘Xanthocarpum’ seeds germinated at moderate rates (55 and 25%, respectively) and were highly viable (100%). ‘Compactum’, ‘Losely's Compact’, and ‘Nanum’ germinated at low rates or failed to germinate (0, 0, and 5%, respectively), yet seeds were moderately viable (37, 65, and 55%, respectively). Seeds of all cultivars germinated at low rates or failed to germinate at both outdoor sites (0 to 5%) which suggests these plants may be weakly invasive. Short-term studies on biological traits such as these provide only limited information to assess the invasive potential of cultivars.
Performance of Mycorrhizal Products Marketed for Woody Landscape Plants
Authors: Eric Wiseman P. , Colvin Kristen H. , Wells Christina E.
Published: August 2020

Commercial products containing propagules of arbuscular mycorrhizal fungi (AMF) are widely marketed to improve woody plant performance in the landscape. However, the infectivity of these products has rarely been subjected to independent testing. We evaluated commercial AMF inoculants in a series of greenhouse experiments using corn (Zea mays), sorghum (Sorghum bicolor), trident maple (Acer buergerianum), and sweetbay magnolia (Magnolia virginiana) as host plants. In corn and sorghum, colonization rarely exceeded 5% when plants were treated with commercial inoculants. In contrast, viable lab-cultured inoculant of similar species composition yielded mean colonization percentages of 38 to 61%. Despite the near absence of colonization, commercial inoculants generally improved shoot growth and increased soil nutrient concentrations in a dose-dependent manner. Commercial inoculants had no effect on mycorrhizal colonization or shoot growth of trident maple or sweetbay magnolia liners. Product-treated magnolias grown from seed also developed little or no mycorrhizal colonization, whereas plants treated with a lab-cultured inoculant were 74% colonized. If commercial AMF inoculants are to receive broad acceptance as landscape soil amendments, manufacturers must demonstrate that their products can promote mycorrhizal colonization under the conditions of their intended distribution and use.
Preemergence Control of Black Cottonwood in Nursery Containers
Authors: Altland James E.
Published: August 2020

Two experiments were conducted to evaluate preemergence herbicides for control of black cottonwood (Populus trichocarpa) in nursery containers. In 2006, granular preemergence herbicides were applied to recently filled, weed-free containers in May just prior to seed release from mature cottonwood trees. Flumioxazin provided the most effective cottonwood control, although control with isoxaben + trifluralin, oxyfluorfen + oryzalin, and pendimethalin was also effective. In 2007, containers were filled February 15, and herbicides were applied to separate groups of containers on February 22, March 14, April 16, and May 15. Containers were over-seeded with cottonwood for a 2-week period starting on May 16. Control with most herbicides improved as the date of application neared the date of seeding. Flumioxazin provided the most effective control throughout the experiment, but control from it also improved as the date of application neared the time of seeding.
Bare Root Liner Production Can Alter Tree Root Architecture
Authors: Hewitt Angela , Watson Gary
Published: August 2020

Typical nursery production practices, such as root pruning and transplanting, can alter tree root architecture and contribute to root systems that are too deep. In a study of field-grown liner production, root architecture was examined at each stage of the production process, from first year seedlings or rooted cuttings, through 4 to 5 year old branched liners. Depth and diameter of structural roots were recorded on ten replications each of Acer saccharum, Gleditsia triancanthos, Pyrus calleryana, and apple seedling rootstocks; Platanus ‘Columbia’ clonal rooted cuttings; and apple EMLA 111 clonal rootstock produced by mound propagation. By the time the liners reached marketable size, most natural lateral roots emerging from the primary root were lost. Simultaneously, adventitious roots were produced deeper on the root shank at the pruned end of the primary root. These changes in architecture result in the formation of an ‘adventitious root flare’ that is deeper in the soil than a natural root flare. The depth of this new root flare is dependent upon nursery production practices and may influence the ultimate depth of structural roots in the landscape.
Effect of Fabric and Plastic Containers on Plant Growth and Root Zone Temperatures of Four Tree Species
Authors: Tauer Pamela K. , Cole Janet C.
Published: August 2020

Live oak (Quercus virginiana Mill.), red maple (Acer rubrum L.), and sweet gum (Liquidambar styraciflua L.) trees were planted in #7 fabric or plastic containers on April 18, 2004, and grown for two growing seasons. Live oak and golden rain tree (Koelreuteria paniculata Laxm.) trees were planted in #10 fabric or plastic containers on May 6, 2005, and harvested the following summer. Plant height, canopy width, and caliper were measured periodically, and root zone temperatures were recorded at 30-min intervals throughout each study. In the 2004 planting, live oak height and canopy width increased more for plants in plastic containers than for those in fabric containers from May to July 2004. In contrast, no difference in live oak height or canopy width growth occurred between container types from July to September 2004, but trunk caliper increased more in plastic than in fabric containers during this time interval. No differences between container treatments were noted for any measured parameter for red maple or sweet gum trees planted in 2004 or for golden rain tree or live oak trees planted in 2005 at any measurement interval during the study. Average monthly high and low substrate temperatures were similar between the two container types throughout the study. Fabric containers appear to be a reasonable alternative to plastic containers for above ground nursery crop production, although small differences in growth occur for some species.