bluuebunny/crossref_metadata_2025 huggingface dataset:
A Germination Protocol for Small Seed Lots
Authors: Munson Richard H. , Nicholson Robert G.
Published: August 2020

The nursery industry depends on public gardens to supply propagation material for newly introduced plant species grown from seed. Most seed obtained by public gardens is received in small quantities and must be handled efficiently to assure at least minimal germination. A seed germination protocol is proposed which leads the propagator through a series of steps including a systematic search of the literature, a comparison of species about which little or nothing is known to related species with known propagation methods, a study of the climatic conditions present in the seeds' native area, a study of ecological factors that may affect germination, and finally to the propagation process itself. Examples are provided which illustrate how the protocol is used.
Landscape Installation Firms: I. Business Characteristics and Trends Affecting Industry Performance
Authors: Garber M.P. , Bondari K.
Published: August 2020

A survey of landscape installers in Georgia gathered information that would help segments of the green industry work together more effectively. We received 80 completed questionnaires for a 42.3% response rate. Approximately 76% of the firms surveyed were in the metro Atlanta area with 79% of all landscape projects located in Atlanta, Georgia. Georgia firms conducted approximately 98% of their business in Georgia. Three size classes of firms were established based on the 1993 wholesale value of plant material purchased, small (≤ $50K), medium ($50K-$200K), and large (> $200K). Approximately 20% of the firms accounted for 80% of the plants purchased. Large firms had a higher percentage of their projects designed by a landscape architect as compared to small or medium sized firms. Industry trends most frequently identified as having a potential positive impact on the industry over the next five years were: (1) an improving economy due to low interest rates (25.4%), (2) growing consumer interest in the quality of the environment (13.8%), (3) better consumer understanding of the value and benefits of landscaping (12.3%), (4) population growth in Atlanta area (12.3%), and (5) increased industry professionalism and establishment of minimum standards (9.4%). The five trends with the greatest potential for negative impact on the industry were identified as: (1) government mandated employee benefits (23.0%), (2) competitors that bid below the reasonable cost for a job (21.6%), (3) government regulations and taxes (15.8%), (4) increased interest rates (10.8%), and (5) more start-up companies and out-of-state competition (9.4%).
Cyclic Microirrigation in Container-grown Landscape Plants Improves Plant Growth and Water Conservation
Authors: Beeson R. C. , Haydu J.
Published: August 2020

Four tree (Acer rubrum L., Ulmus alata Michx., Quercus virginiana Mill, and Lagerstroemia indica L.) and two landscape shrub species (Rhododendron indicum L. ‘Formosa’ and Elaeagnus pungens Thunb.) were grown in 10-liter (#3) polyethylene containers. Plants were irrigated with overhead impact sprinklers (control) or with individual low volume spray stakes. Microirrigated treatments consisted of same or double volume per day per container as controls applied as one to three cyclic subvolumes. Shrub growth was seldom influenced by irrigation treatment. Xeric tree species (U. alata and Q. virginiana) grew as well with single volumes applied in 2 cycles as double volumes applied in 3 cycles; both produced significantly larger trees than the control. Mesic species (A. rubrum and L. indica) irrigated with double volumes in 3 cycles produced the largest trees that were significantly larger than single volume microirrigated or control trees. Growth of single cycle, single volume trees (overhead and microirrigation) was equivalent; thus, growth effects were due to cycling, not microirrigation. With commercially representative container spacings used, superior trees were produced with cycled microirrigation using 25% (xeric) or 50% (mesic) of the water volume per area applied through the overhead sprinkler. Further aspects of irrigation requirements and water efficiency are discussed.
Effects of Four Compaction Remediation Methods for Landscape Trees on Soil Aeration, Mechanical Impedance and Tree Establishment
Authors: Day S. D. , Bassuk N. L. , van Es H.
Published: August 2020

Landscape trees are often planted in heavily compacted soils around newly constructed buildings or in urban areas. Under such conditions, trees frequently die, or decline prematurely. Four techniques for improving tree establishment on such sites were studied: peat-amended backfill; vertical drainage mat panels; radiating trenches filled with sandy loam soil; and vertical, gravel-filled sump drains. Sugar maple (Acer saccharum ‘Seneca Chief’), a species sensitive to soil compaction, and the less sensitive Callery pear (Pyrus calleryana ‘Redspire’) were planted bare root into treatments in a compacted silty clay loam soil. Controls were backfilled with native soil. Shoot and root growth were measured over three growing seasons. Soil air oxygen content was monitored for one year. Effects of treatments on soil compaction were characterized using measurements of both soil strength and bulk density. Shoot growth of pears was greatest for treatments that alleviated mechanical impedance (soil trenches and amended backfill) and least for treatments that did not (controls and vertical drains). Drainage mats, which may alleviate mechanical impedance to a lesser degree, showed intermediate growth. Root growth was well correlated with shoot growth. Length of 2 to 5-mm diameter roots was greater for pears in soil trench treatments than for those with no treatment (controls) at the end of 3 growing seasons. Vertical drainage mats and vertical gravel-filled sump drains were shown to increase O2 percent in surrounding soil. Regardless of treatment, all oxygen levels were usually close to atmospheric levels and never lower than 10%. Maple mortality was high and no treatment effects were shown.
Chopped Newspaper for Weed Control in Nursery Crops
Authors: Pellett Norman E. , Heleba David A.
Published: August 2020

Chopped newspaper was evaluated as a weed control mulch for nursery row crops. Newspaper mulch at 2.3 and 3.6 kg/m2 [4.2 lb/yd2 (≈ 10 cm or 4 in depth) and 6.3 lb/yd2 (≈ 15 cm or 6 in depth), resp.] suppressed weed germination for two seasons without a negative effect on Daphne burkwoodii ‘Carol Mackie’, Physostegia virginiana, and Salix caprea. Gaillardia grandiflora had less growth when mulched with newspaper during one experiment, but not in another. The authors observed that wetting the newspaper mulch after application followed by compression with a lawn roller pressed the paper into a mat which resisted blowing and weathering. Further reduction in blowing of paper mulch was achieved by applying a tackifier after rolling. Bark mulch at 19.4 dm3/m2 (988 in3/yd2 ≈ 10 cm or 4 in depth) resulted in weed suppression comparable to either of the two rates of newspaper mulch and better than bark at 9.7 dm3/m2 (494 in3/yd2 ≈ 5 cm or 2 in depth). All mulch treatments moderated maximum soil temperatures on July 5, 1993 at 7.5 cm (3 in) depth by more than 10C (18F) when non-mulched soil increased to 36C (96.8F). The rate or type of mulch applied resulted in similar summer soil temperatures at 2.5 and 7.5 cm (1 and 3 in) soil depth.
Proving the Economic Importance of the Greenhouse, Nursery and Sod Industry: A New Jersey Case Study
Authors: Tavernier Edmund M. , Li Farong , Thatch Daymon W.
Published: August 2020

The economic contribution of the greenhouse, nursery and sod (GNS) sector to the economy of New Jersey was analyzed using Impact Analysis for Planning (IMPLAN). The results were analyzed in terms of employment, employee compensation, and total industry output, and were disaggregated into direct, indirect and induced effects of GNS activity. The analysis shows that the direct contribution of the GNS sector generated substantial indirect and induced economic effects in the real estate sector. The indirect effects were also great for the wholesale, agricultural services and agricultural chemicals sector, while the general merchandise, and the apparel and accessories sectors experienced major gains from the induced effects of GNS activity.
Granular Preemergence Applied Herbicides Influence Annual Bedding Plant Growth
Authors: Thetford Mack , Gilliam Charles H. , Williams J. David
Published: August 2020

Three experiments were conducted to evaluate effects of preemergence applied herbicides on annual bedding plants. In experiment 1, five preemergence applied herbicides were evaluated for control of large crabgrass (Digitaria sanguinalis L. Scop.) and prostrate spurge (Euphorbia humistata Engelm. ex Gray) and phytotoxicity to spring planted herbaceous bedding plants. Dimension 0.5G (dithiopyr) applied at 1.1, 2.2 or 3.4 kg ai/ha (1.0, 2.0, or 3.0 lb ai/A), Southern Weedgrass Control (SWGC) (pendimethalin) 2.68G and Rout 3G (oxyfluorfen + oryzalin) each applied at 1.7, 3.4 or 6.7 kg ai/ha (1.5, 3.0 or 6.0 lb ai/A), Snapshot 2.5TG (trifluralin + isoxaben) applied at 3.4 or 6.7 kg ai/ha (3.0 or 6.0 lb ai/A) and Ronstar 2G (oxadiazon) applied at 4.5 kg ai/ha (4.0 lb ai/A) controlled both weeds up to 60 days after treatment (DAT). Bedding plant tolerance varied with herbicide and application rate. Basil and salvia were sensitive to Snapshot (trifluralin + isoxaben) [6.7 kg ai/ha (6.0 lb ai/A)], while Ronstar (oxadiazon) [4.5 kg ai/ha (4.0 lb ai/A)] injured begonia and impatiens. Species sensitive to Dimension (dithiopyr) at 2.2 or 3.4 kg/ha (2.0 and 3.0 lb ai/A) 60 DAT were begonia, salvia, and nicotiana. Bedding plants sensitive to SWGC (pendimethalin) were celosia and salvia. Rout (oxyfluorfen + oryzalin) was injurious to most species evaluated at 6.7 kg ai/ha (6.0 lb ai/A) and in some cases at 3.4 kg ai/ha (3.0 lb ai/A). In experiments 2 and 3, shoot growth of impatiens, geranium, basil, and ageratum was not affected by any herbicide treatment. However, impatiens root growth was suppressed (30 DAT) with Dimension (dithiopyr), Snapshot (trifluralin + isoxaben), SWGC (pendimethalin) (high rate only), and Ronstar (oxadiazon). Basil root growth was suppressed 15 DAT with Dimension (dithiopyr), Snapshot (trifluralin + isoxaben), and SWGC (pendimethalin); however, all root dry weights were similar to control root dry weights at 30 DAT.
Variation in Response of Selected American Elm Clones to Ophiostoma ulmi
Authors: Townsend A.M. , Bentz S.E. , Johnson G.R.
Published: August 2020

Ramets of nine American elm (Ulmus americana L.) clones or cultivars were planted with ramets of Ulmus ‘Frontier’, Ulmus ‘Prospector’, and American elm seedlings in a randomized block, split-plot design. When they were three years old, the trees were inoculated in the main trunk on either one of two selected dates in May with a spore suspension of Ophiostoma ulmi, the causal fungus for Dutch elm disease (DED). Analyses of variance showed significant variation among clones and between inoculation dates in disease symptoms four weeks and one year after inoculation. Inoculations made on May 18 generally created significantly more symptoms than inoculations made only nine days later. Four-week symptom expression was influenced also by a significant interaction between clonal or seedling group and inoculation date. When data from both inoculation dates were combined, six American elm clones (‘American Liberty’, ‘Princeton’, 680, R18–2, 180, and 3) showed significantly fewer foliar symptoms after four weeks than the American elm seedlings and three other American elm clones. Five of these same six more tolerant American clones averaged significantly less crown dieback after one year than the other American clones or seedlings tested. One of the American elm clones (clone 3) showed a level of disease tolerance equal statistically to ‘Frontier’ and ‘Prospector’, two cultivars which have shown a high degree of tolerance to DED in other studies.
Cyclic Irrigation and Media Affect Container Leachate and Ageratum Growth
Authors: Fare Donna C. , Gilliam Charles H. , Keever Gary J. , Reed R. Bruce
Published: August 2020

Two experiments were conducted with container-grown Ageratum houstonianum Mill. ‘Blue Puffs’ to compare cyclic and continuous irrigations. In experiment 1, leachate volumes were reduced about 54% with 0.4 cm (0.16 in) cyclic irrigation treatments applied with either a 30 min or 2 hr resting phase compared to continuous inigation of 0.4 cm (0.15 in). Total N leached was about 47% less with the cyclic treatments compared to continuous irrigation. In experiment 2, container leachate volumes and N leached were higher from a pine bark:sand medium, while plants were smaller compared to a pine bark:peat medium. Growth index and root distribution weresimilar with cyclic and continuous irrigation.
Ground Ivy (Glechoma hederacea L.) Control in a Kentucky Bluegrass Turfgrass with Borax
Authors: Hatterman-Valenti Harlene , Owen Micheal D. K. , Christians Nick E.
Published: August 2020

Field experiments were conducted to evaluate ground ivy (Glechoma hederacea L.) control and Kentucky bluegrass (Poa pratensis L.) tolerance to Twenty Mule Team Borax, Super Trimec, and Sharpshooter applications. Ground ivy control improved with time in 1991 whereas the inverse was true in 1992. Liquid borax at 610 g/100m2 and Super Trimec at 560 ml/100m2 controlled ground ivy consistently (≥85%) during 1991 and 1992. Ground ivy control with dry borax was not as good as liquid borax when each application was applied at 305 g/100m2. Unacceptable ground ivy control occurred with Sharpshooter. All treatments caused turfgrass injury in 1991. At 4 weeks after treatment (WAT), injury increased to 30 and 40% for the 305 and 610 g/100 m2 (10 and 20 oz/1000 ft2) liquid borax treatments, respectively. No turfgrass injury however was observed the following spring. In 1992, only Sharpshooter caused injury 2 WAT. Weather differences after the applications contributed to the variability in ground ivy control and turfgrass injury between years. These results indicate that boron can be used to selectively control ground ivy in a Kentucky bluegrass turf with a 610 g/100 m2 (20 oz/1000 ft2) liquid borax application with only temporary turfgrass injury.
Landscape Maintenance Firms: III. Opportunities for Cooperation in the Landscape/Nursery Industry
Authors: Garber M.P. , Bondari K.
Published: August 2020

Landscape maintenance firms in Georgia identified opportunities for landscape architects, landscape installers, growers, and university personnel to better serve their industry. The primary opportunities for landscape architects were to consider plant maintenance in the design stage (32.9%) and to specify plants with proven performance (27.6%). Landscape installers were asked to improve planting techniques (39.2%) and perform their own installation activities to ensure quality (27.5%). The top 2 opportunities for growers were improved quality and size standards for plant material (22.4%) and to supply new and different plants (16.4%). University personnel were asked to provide training and certification courses (37.9%) and landscape maintenance publications with information on pest management (19.7%). Landscape maintenance firms also identified the most common complaints received from their customers and the sources of information that influenced which plants to purchase. This information provides valuable insight into the needs of landscape maintenance firms and establishes a basis for more effective cooperation and marketing in the nursery/landscape industry.
Nursery Production Method Affects Root Growth
Authors: Gilman Edward F. , Beeson Richard C.
Published: August 2020

This study compared growth and biomass distribution on two commonly grown trees produced in plastic containers with those in fabric containers and in the field. Shoot: root ratio on field-grown and fabric container-grown laurel oak (Quercus laurifolia Michx.) was higher than on holly (Ilex × attenuata Ashe. ‘East Palatka’). Ratios were similar for trees grown in plastic containers. Compared to oaks, a larger portion of holly root balls was comprised of small diameter roots. Root spread of field-grown laurel oak was similar to those produced in fabric containers. Trees of both species growing in plastic containers had several times more fine root mass (roots 2 mm or less diameter) within the root ball than those dug from the field or fabric containers. Total root ball root weight in plastic containers was less than in field-and fabric container grown trees. Root weight inside the root balls for field-grown and fabric container-grown trees was similar but field-grown root balls were twice the volume. Only 17% (field) and 26% (fabric containers) of holly root weight within the root ball was from roots 10 mm or less in diameter. However, 48% percent of root weight on trees grown in plastic containers was in this diameter class. Between 68 and 84%, depending on species and production method, of total-tree root weight was inside the root ball. Between 10% and 18.1%, depending on species and production method, of roots 2 mm or less in diameter was inside the root ball.
Variation in Growth and Response to Ophiostoma ulmi among Advanced-Generation Progenies and Clones of Elms
Authors: Townsend A. M. , Douglass L. W.
Published: August 2020

Controlled pollinations between five disease-tolerant elm (Ulmus L.) clones (Number 970, ‘Urban’, and clones that were later named ‘Homestead’, ‘Pioneer’, and ‘Prospector’) yielded 686 seedlings. Various crosses produced from zero to over 90 seedlings. Only one of four female parents produced any viable selfed seedlings. At age four, all seedlings were inoculated with Ophiostoma ulmi, (Buism.) C. Nannf., the causal fungus for Dutch elm disease. A factorial analysis showed male parent, female parent, and male x female interaction influenced disease symptoms 4 and 8 weeks after inoculation. After a few years of further evaluation of the seedlings, 10 clones were selected for a combination of disease- and insect-tolerance and horticultural desirability. These clones were propagated and established along with four disease-tolerant cultivars and American elm seedlings in a replicated field plot. Three-year-old clonal plants inoculated with O. ulmi varied significantly in their disease symptoms 4 weeks, 1 year, and 2 years after inoculation. Even clones from the same full-sib family showed significant differences in disease tolerance. Results indicate that both specific and general combining ability are important in determining tolerance to Dutch elm disease.
Differential Resistance to Entomosporium Leafspot Disease and Hydrogen Cyanide Potential in Photinia
Authors: Jacobs K. A. , Santamour F. S. , Johnson G. R. , Dirr M. A.
Published: August 2020

Photinia serrulata Lindl., P. glabra (Thunb. ex J.A. Murr.) Maxim., and two of their progeny, P. x fraseri Dress. ‘Birmingham’ and ‘Kentucky’ were screened for susceptibility to Entomosporium leafspot and for hydrogen cyanide potential using detached leaf assays. Photinia serrulata was least susceptible to the fungus, while P. x fraseri ‘Birmingham’ and P. glabra were most susceptible. Young leaves were much more susceptible than mature leaves in all taxa except P. glabra, which was found to be acyanogenic. Although distinct differences in hydrogen cyanide potential occurred among the clones, a direct correlation to disease susceptibility was not indicated.
Growth and Flowering of Three Garden Chrysanthemum Cultivars Produced in Plastic or Copper-Impregnated Fiber Containers
Authors: Ruter John M.
Published: August 2020

A study was conducted with three garden chrysanthemum cultivars (Dendranthemum × grandiflorum (Ramat.) Kitamura), ‘Grenadine’, ‘Nicole’, and ‘Tolima’ to evaluate growth and flowering in 2.6 liter (#1) black plastic containers compared to copper hydroxide (Cu(OH)2) impregnated fiber containers. For all three cultivars, growth indices, shoot and root dry weights, and total biomass increased for plants grown in fiber containers. Total number of flower buds per plant increased 30 to 32% for ‘Grenadine’ and ‘Nicole’ and 53% for ‘Tolima’ in fiber containers. Plants grown in Cu(OH)2-impregnated fiber containers had less root coverage at the containensubstrate interface and no observable root circling in contrast to visible root circling of plants grown in black plastic containers. Foliar nutrient analysis on the cultivar ‘Grenadine’ showed that K decreased and Fe and Cu increased when grown in Cu(OH)2-impregnated fiber containers. No visible nutrient abnormalities were observed.
Cyclic Irrigation Increases Irrigation Application Efficiency and Decreases Ammonium Losses
Authors: Tyler Helen H. , Warren Stuart L. , Bilderback Ted E.
Published: August 2020

Cyclic irrigation using pressure compensated drip emitters was evaluated for irrigation application efficiency, nutrient efficacy, and plant growth. The experiment, a RCBD with four replications was conducted in a simulated nursery using high volumes of irrigation which are common in container-grown ornamental nurseries in the southeastern United States. A container-grown plant production area, subdivided into 16 separate plots, allowed for the collection of all irrigation water leaving each plot. Rudbeckia fulgida Ait. ‘Goldsturm’ and Cotoneaster dammeri Schneid. ‘Skogholm’ plants were potted into 3.8 liter (#1) containers in a pine bark: sand substrate (8:1 by vol) and irrigated with either 900 ml (1.2 in) of water applied once a day [900 ml (1×)], 450 ml (0.62 in) applied in two cycles [450 ml (2×)], 300 ml (0.41 in) applied in three cycles [300 ml (3×)], or 150 ml (0.21 in) applied in six cycles [150 ml (6×)]. A cycle consisted of a one-hour rest interval between each irrigation allotment. At 8:00 AM daily, volume of effluent from each plot was measured and a sub-sample of the effluent was analyzed for NO3-N, NH4-N, and P. Cycled irrigation (2×, 3×, 6×) reduced volume of effluent, increased irrigation application efficiency [(irrigation volume applied-volume leached) ÷ volume applied], and decreased total NH4-N (mg) losses compared to the 900 ml (1×) application. Cycled irrigation (2×, 3×, 6×) did not differ in effluent volume or irrigation application efficiency. However, the 450 ml (2×) treatment had greater total NH4-N losses compared to 300 ml (3×) and 150 ml (6×) treatments. Irrigation treatments did not affect NO3 or P losses. Irrigation application efficiency over the course of the experiment averaged 0.52 for cyclic irrigation applications (2×, 3×, 6×), a 38% improvement over the 900 ml (1×) standard application. Depending on irrigation treatment, 89% to 104% of the 3.0 g of N applied was recovered. Nitrogen efficiency averaged 89% and 88% for cotoneaster and rudbeckia, respectively. Of the 0.34 g of P applied, 43.4% was recovered. Phosphorus efficiency averaged 29% for both species. Growth, nutrient concentration, and nutrient content of cotoneaster or rudbeckia were not affected by irrigation treatments.
Weed Control Strategies for Field Grown Herbaceous Perennials
Authors: Calkins James B. , Swanson Bert T. , Newman Debra L.
Published: August 2020

Fourteen herbicides or herbicide combinations, wood chip mulch, chipped rubber tire mulch, and newspaper mulch were evaluated for weed control efficacy and phytotoxicity using 12 species of herbaceous perennials under field growing conditions. The effect of herbicide application time was monitored by applying herbicides to dormant and actively growing plants. Herbicide and mulch treatments were compared to weeded and non-weeded controls. Herbicide phytotoxicity was dependent on age and species of herbaceous perennial and time of herbicide application. Herbicide injury was generally greater for young plants compared to established plants and phytotoxicity was usually reduced when herbicides were applied to dormant rather than actively growing plants. Injury was sometimes greater when herbicides were applied in early spring compared to applications made after complete herbaceous perennial emergence. Injury to young shoots that had emerged prior to the earliest possible time that herbicides could be applied in the spring was probably involved. Applying herbicides in the fall may avoid such injury. Mulching field grown perennials with wood chips provided the most effective weed control and often the best quality plants. With the exceptions of Hemerocallis ‘After Dark’ and Phlox maculata ‘Omega’, the herbaceous perennials evaluated were tolerant of most of the herbicides applied. Several herbicides, including Balan 2.5G at 3.36 kg ai/ha (3.0 lb ai/A), Snapshot 80DF at 4.48 kg ai/ha (4.0 lb ai/A), and Stomp 60WDG at 4.48 kg ai/ha (4.0 lb ai/A), demonstrated potential for weed control in herbaceous perennial production systems and landscape plantings. Goal 1.6EC at 1.68 kg ai/ha (1.5 lb ai/A) and Ronstar 50WP at 3.92 kg ai/ha (3.5 lb ai/A) were often phytotoxic when applied to herbaceous perennials.
Tank-Mixed Postemergence Herbicides for Postemergence Goosegrass Control in Bermudagrass Turf
Authors: Jack Johnson B.
Published: August 2020

Goosegrass [Eleusine indica (L.) Gaertn.] continues to be a major weed problem in bermudagrass (Cynodon spp.)throughout the southern United States. A field experiment was conducted during 1995 and 1996 in Georgia to determine if tank-mixed postemergence herbicides would improve goosegrass control in common bermudagrass [Cynodon dactylon (L.) Pers.] turf. Illoxan (diclofop), MSMA plus Sencor (metribuzin), MSMA plus Sencor with Princep (simazine), and selected rates of Illoxan with Princep controlled goosegrass effectively (≥83%) for 8 weeks in 1995. However, the control was ineffective (<80%) for any treatment by 8 weeks in 1996. The higher control in 1995 was probably related to higher air temperature [mean high temperature was 35C (95F) for 14 days after treatment] compared to 1996 [32C (89F) during the same period]. Tank-mixes of Princep with MSMA did not improve goosegrass control compared with Illoxan alone. Addition of Princep to MSMA, MSMA plus Sencor, or Illoxan did not increase bermudagrass injury compared to these treatments applied without Princep.
An Evaluation of Repetitive Summer Horticultural Oil Sprays on Selected Woody Landscape Plants
Authors: Miller Fredric
Published: August 2020

In order to evaluate the effect of repetitive verdant horticultural oil sprays on plant growth and appearance, 32 different species/cultivars of shade trees, evergreens, and woody shrubs were sprayed three times during the 1994 growing season with 2% SunSpray Ultra-Fine spray oil. Visual phytotoxicity ratings were assigned to treated plants and growth affects were measured by measuring leaf area and incremental twig growth following the last spray application. No phytotoxicity was observed on any of the 32 species/cultivars of woody plants using three repetitive verdant horticultural oil sprays. Collectively, repetitive oil sprays did not significantly affect incremental twig growth or leaf area of treated plants. Results from this study show that repetitive sprays of 2% SunSpray Ultra-Fine spray oil can be used safely on shade trees, evergreens, and deciduous landscape shrubs commonly grown in the upper mid-west.
Controlling Rooting-Out of B&B Nursery Stock During Storage
Authors: Maynard Brian K. , Johnson William A.
Published: August 2020

Cupric hydroxide formulated as Spin Out™ (7% Cu(OH)2 in a latex carrier, w/w) was used to prevent rooting-out of Taxus × media Rehd. ‘Densiformis’ root balls into surrounding mulch or soil during storage over a four-month period. Treatments included: painting the bottom of the root ball with Spin Out™, setting the root ball on Spin Out™-treated burlap or on untreated burlap, and rewrapping the root ball with Spin Out™-treated burlap or burlapping using Spin Out™-treated burlap before mulching. All treatments provided some control of rooting-out after 12 to 16 weeks storage. The most effective treatments were 1) in unmulched situations, setting the root ball on Spin Out™-treated burlap (92% reduction in root count after 16 weeks), and 2) in mulched situations, either rewrapping or burlapping with Spin Out™-treated burlap (90% and 86% reduction in root count, respectively, after 16 weeks). Using Spin Out™-treated burlap to prevent rooting-out during storage can reduce the incidence of re-balling and root removal prior to shipping and planting stored B&B nursery stock.
Half-Sib Family Selection Improves Container Nursery and Landscape Performance of Sycamore
Authors: Shoemake Larry J. , Arnold Michael A.
Published: August 2020

Seven groups of seedlings from each of seven single parent (half-sib) families of sycamore, Platanus occidentalis L., were grown to a marketable size in 9.1 liter (#3) containers to test responses to container nursery production in south Texas. Seedlings were then transplanted to a field site (Brazos County, TX) in the fall, spring, and summer to assess seasonal effects on landscape establishment. Regional selections grew larger, both during container production and following subsequent transplant to the field. Growth of nonimproved local half-sib families equaled or exceeded that of genetically improved families from a distant region. Differential responses among genetically improved and non-improved sources were less pronounced when genotypes were grown in a region from which they did not originate. Fall and spring transplanted seedlings had substantially greater growth and survival than did summer transplants regardless of genotype. This study demonstrates a potential for regional market segregation of seed-propagated landscape trees.
Growth of Viburnum dentatum and Syringa × prestoniae ‘Donald Wyman’ in Sphagnum Peat and Coir Dust-Based Substrates
Authors: Evans Michael R. , Iles Jeffery K.
Published: August 2020

Bare-root viburnum (Viburnum dentatum L.) were grown in 25:0:75, 50:0:50, 75:0:25, 100:0:0, 0:25:75, 0:50:50, 0:75:25, and 0:100:0 peat:coir:sand (by vol) substrates, and Preston lilac (Syringa × prestoniae McKelv. ‘Donald Wyman’) were grown in 25:0:65:10, 50:0:40:10, 75:0:15:10,0:25:65:10, 0:50:40:10, and 0:75:15:10 peat:coir:bark:sand (v/v) substrates over two seasons. After one season of growth, viburnum grown in 25% and 50% coir were taller than plants grown in comparable peat-based substrates, and overall, plants grown in coir-based substrates were taller than plants grown in peat-based substrates. Lilac plants grown in coir-based substrates had similar heights as plants grown in peat-based substrates. After two seasons, viburnum grown in 100% coir had greater plant width than plants grown in 100% peat. No significant difference occurred between plants grown in 25% and 50% peat or coir. No significant difference occurred in shoot fresh mass between viburnum plants grown in coir and peat-based substrates. However, those grown in 50% and 100% coir had greater root fresh mass than those grown in comparable peat-based substrates. Overall, root fresh mass was greater for plants grown in coir-based substrates than peat-based substrates. After two seasons, height and root fresh mass were not significantly different between substrates for lilac. Plant width was greater for plants grown in 25% and 50% coir than for plants grown in 25% or 50% peat. Plants grown in 75% coir had greater shoot fresh mass than plants grown in 75% peat.
Recycled Waste Paper as a Landscape Mulch
Authors: Smith D. R. , Gilliam C. H. , Edwards J. H. , Eakes D. J. , Williams J. D.
Published: August 2020

Two studies were conducted to evaluate recycled waste paper mulch for landscape plantings. In the first study, two recycled paper products (pellet and crumble) were applied at three depths. Application of recycled paper mulch at a depth of 25 or 50 mm (1 or 2 in) controlled prostrate spurge. However, in experiment 1, all four bedding plant species exhibited stunting of roots and shoots. In the second study, three annual species were mulched with the two recycled paper products applied at 25 mm (1 in) depth and treated with phosphorus (P) at 0, 3.75, or 7.5 mgL−1 (ppm) to bind suspected excess aluminum (Al). When no P was added, growth of ageratum was approximately half that of the non-mulched control plants. Addition of P at either rate resulted in similar growth compared to control plants. Shoot dry weight of geranium was greater than that of the control plants with 7.5 mg L−l of P. Shoot dry weight of marigold was unaffected by the addition of P. This research indicates that recycled paper mulch at a 25 mm (1 in) depth, provides weed control equal to or better than standard landscape treatments, and causes little or no growth suppression when amended with P.
Effects of Primo Rate and Application Volume on Selected Herbaceous and Woody Landscape Plants
Authors: Keever Gary J. , Olive John W.
Published: August 2020

Primo (cimectacarb) was applied to four herbaceous and six woody landscape plants at rates and in volumes recommended for turfgrass application. Phytotoxic symptoms, including bleaching or bronzing of foliage or bleaching of flowers, occurred in coleus, petunia, butterfly bush and azalea (Southern Indica cultivar). In general, symptoms were more severe with increasing Primo rate, while application volume had less effect. Effects on shoot growth were minimal and not considered of practical significance in a landscape setting.
Root Pruning Red Maple and Washington Hawthorn Liners Does Not Affect Harvested Root Length After Two Years of Field Production
Authors: Roger Harris J. , Fanelli Jody
Published: August 2020

Root pruning field-grown trees during production can increase harvested root length, but it is a time consuming and expensive practice. Root pruning before lining out instead of during production is much faster and cheaper. This study tested the effect of root pruning red maple (Acer rubrum L.) and Washington hawthorn (Crataegus phaenopyrum (L.f.) Medic.) trees. Bare-root liners were root pruned before planting in nursery rows, and top growth, shoot: root ratios, and harvested root length within rootballs were measured after two years of field growth. Pruning root systems back 25%, 50%, or 75% had little effect on top growth or shoot:root ratios for either species.
Greenhouse Conditioning Affects Landscape Performance of Bedding Plants
Authors: Latimer Joyce G. , Oetting Ronald D.
Published: August 2020

Conditioning treatments were evaluated for effects on growth of bedding plants during greenhouse production and carryover effects on plant performance in the landscape. Treatments included two fertilization regimes using a complete water soluble fertilizer applied three times/week at 500 ppm N, designated ‘high N’, or at 50 ppm N, designated the ‘low N’ treatment. Other treatments included: ebb and flow irrigation, drought stress for up to 2 h wilt/day, 5000 ppm B-Nine (daminozide), 45 ppm Bonzi (paclobutrazol; 180 ppm on columbine), and brushing (40 strokes twice daily). Unless otherwise noted all plants, including controls, were maintained well-irrigated and fertilized with 250 ppm N three times/week. Marigolds and New Guinea impatiens grown under low N during greenhouse production exhibited reduced plant height and width relative to control plants at 4 weeks after planting (WAP) in the landscape. Plant quality ratings of all species conditioned with low N were lower than those of controls 2 and 4 WAP. Plant height of New Guinea impatiens conditioned with high N was greater than that of controls 4 WAP in the landscape. Marigolds subjected to drought in the greenhouse were still shorter than controls 2 and 4 WAP. Persistent height reductions in the landscape in response to B-Nine were observed in ageratum 2 and 4 WAP and to Bonzi in New Guinea impatiens through 8 WAP. Brushing reduced the height of all species except ageratum in the greenhouse, but had no carryover effect on plant growth in the landscape. At 4 weeks after treatment, plant height of columbine treated with low or high N, drought, brushing, or B-Nine was reduced relative to controls, but all plants were similar in size in the landscape.
Influence of Storage Temperatures on Long-term Seed Viability of Selected Native Ericaceous Species
Authors: Glenn Christopher T. , Blazich Frank A. , Warren Stuart L.
Published: August 2020

Following harvest of capsules, drying, and seed extraction, seeds of Kalmia latifolia L. (mountain laurel), Leucothoe fontanesiana (Steud.) Sleum (drooping leucothoe), Rhododendron carolinianum Rehd. (Carolina rhododendron), Rhododendron catawbiense Michx. (Catawba rhododendron), and Rhododendron maximum L. (rosebay rhododendron) were stored for 0, 1, 2, 3, 4 or 5 years at −18,4 or 23C (0, 39 or 73F) and then germinated at 25C (77F) or an 8/16 hr thermoperiod of 25/15C (77/59F) with daily photoperiods of 0, 1 or 24 hr. Storage at −18 or 4C (0 or 39F) were most effective for maintaining seed viability of all species. After 5 years storage at −18 or 4C (0 or 39F), viability of L. fontanesiana, R. catawbiense, and R. maximum was relatively unchanged with total germination of 59%, 87%, and 88%, respectively. The same was noted for seeds of K. latifolia and R. carolinianum with total germination of 77% and 91%, respectively, after storage for 4 years at the same temperatures. Storage at 23C (73F) was the least effective for maintaining viability. After storage for 1 year at 23C (73F), germination decreased significantly for all species except R. carolinianum. By year 3, storage at 23C (73F) reduced seed viability of L. fontanesiana to essentially zero. The same occurred by year 4 for seeds of R. catawbiense and R. maximum stored at 23C (73F). Viability of K. latifolia also decreased under storage at 23C (73F) with germination of 14% noted by year 4. Viability of R. carolinianum did not decrease as rapidly as the other species when stored at 23C (73F) with total germination of 77% occurring by year 4. Regardless of storage duration, the photoperiod and temperature requirements for maximum germination of all species did not change.
Characteristics of Garden Writers and Their Information Sources
Authors: Garber M. P. , Bondari K.
Published: August 2020

A national survey of members of the Garden Writers Association of America (GWAA) indicated that Garden Writers tend to distribute their gardening communications within their state of residence and to a lesser extent, nationally. The most widely used media by Garden Writers were newspapers, magazines and television. The three types of plant material information that generated greatest consumer response for Garden Writers were low maintenance plants, herbaceous perennials, and new plant varieties. The type of services or information that Garden Writers valued the most were new plant releases, current pest problems in their area, and a listing of local suppliers of new plant varieties. Garden Writers maintain home gardens (97.3%) and most evaluate new plant varieties (88.1%) in their garden.
Evaluation of Ornamental Grasses for the Northern Great Plains
Authors: Davidson C.G. , Gobin S.M.
Published: August 2020

A total of 160 grass or grass-like species/cultivars were evaluated under field conditions for a period of four years. Detailed assessments of survival, growth and development are presented. Horticultural evaluations were completed on all material, providing a basis for making recommendations for utilization of grasses in the landscape in colder regions (USDA zone 3) of the Great Plains. Thirty accessions were identified with very good to outstanding visual appeal. Plants that were rated very high for horticultural value included: big bluestem (Andropogon gerardii), feathertop (Calamagrostis epigejos), many of the sedges (Carex sp.), plumegrass (Erianthus ravennae), Hervier's fescue (Festuca hervierri), Leman's fescue (Festuca lemanii), tall purple rhoorgrass (Molinia caerulea spp. arundinacea cv. Skyracer), switchgrass species and cultivars (Panicum virgatum cv. Haense Herms, Heavy Metal and Strictum), ravenna grass (Saccharum ravennae) and variegated cordgrass (Spartina pectinata cv. Aureo-marginata). Eighteen accessions were removed from the test mainly due to their invasive nature (e.g., Bromus inermis cv. Skinner's Golden, Elymus spp., Glyceria maxima and Phragmites australis). Of the remaining 142 accessions, 71.8% had at least one plant remaining at the end of the test period (1996).
Herbicide Adsorption and Release Properties of Five Oxadiazon-Coated Fertilizers
Authors: Keel Kevin R. , Gilliam Charles H. , Wehtje Glenn R. , Grey Tim L. , Keever Gary J. , Eakes Donald J.
Published: August 2020

Laboratory experiments were conducted to determine the release of oxadiazon coated on control-release fertilizers. Five fertilizers and glass beads (nonabsorbent control) were coated with 14C-oxadiazon + formulated oxadiazon at a herbicide-to-fertilizer concentration of 0.3 mg ai/g. Coated fertilizers were subjected to 14 consecutive daily water leaching events. For the control-release fertilizers, Nutricote, Meister and Osmocote, 70%–80% of the coated oxadiazon was released in the first 3 leaching events; each leaching event after the 7th leaching event contained less than 1% of total applied oxadiazon. In contrast, 56% of the total applied oxadiazon was leached from Polyon 24N–1.7P–10K (24–4–12) in the first 3 leachings and similar percentages of oxadiazon were leached over each of the last 11 leaching events. Coating the five fertilizers with isoxaben produced similar results. A second experiment evaluated the effects of the addition of Prime Oil, Complex (sticker), Plex (sticker), and Intac (sticker) on release rates of oxadiazon-coated Osmocote 17N–3.1P–10K (17–7–12). Oxadiazon-coated Osmocote alone and oxadiazon-coated Polyon alone were also evaluated. Eighty-five percent of the total applied oxadiazon was leached from oxadiazon-coated Osmocote alone during the first leaching event and less than 1% was recovered with each consecutive leaching after the third leaching. Oxadiazon-coated Osmocote treated with Plex responded similarly to oxadiazon-coated Osmocote. Oxadiazon-coated Osmocote treated with Complex, Intac, or Prime Oil and oxadiazon-coated Polyon lost 21%, 20%, 16%, and 24%, respectively, of the applied herbicide after the first leaching event. Thereafter, nearly equal amounts of oxadiazon (5%) were leached from Complex, Prime Oil, Intac and Polyon alone from the 6th through the 11th leaching events.
Cold Hardiness of Weigela Cultivars
Authors: McNamara Steve , Pellett Harold
Published: August 2020

Laboratory freezing tests of stem hardiness were conducted to develop cold hardiness profiles for 18 weigela (Weigela sp.) cultivars during the fall and winter of 1994–95. Tests were performed on containerized plants held in a temperature-controlled greenhouse to prevent exposure to potentially lethal temperatures. No cultivar survived below −6C (21F) in the October 3 test. Subsequent differences in rates of acclimation resulted in cultivars differing in hardiness by as much as 13C (23F) on November 14. Taxa also differed greatly in their maximum midwinter low temperature tolerance with ‘Centennial’ and ‘Eva Supreme’ hardy to −44C (−47F) and −28C (−18F) in mid-January, respectively. None of the cultivars deacclimated substantially in response to a week of artificially-imposed diurnal freeze/thaw cycles in early February. Taxa with the greatest midwinter hardiness also maintained the greatest hardiness in early March. Overall, ‘Centennial’, ‘Java Red’, and ‘Samba’ were the most cold hardy cultivars tested, while ‘Boskoop Glory’, ‘Bristol Snowflake’, and ‘Variegata’ were the least hardy. Cold injury of susceptible weigela cultivars appears to be a consequence of late hardening and/or insufficient midwinter hardiness rather than rapid deacclimation in response to periods of warm temperatures in mid-to late-winter.
Secondary Seed Dormancy of Rhododendron catawbiense and Rhododendron maximum
Authors: Glenn Christopher T. , Blazich Frank A. , Warren Stuart L.
Published: August 2020

Seeds of Rhododendron catawbiense Michx. (Catawba rhododendron) and Rhododendron maximum L. (rosebay rhododendron) were germinated at 25C (77F) or an 8/16 hr thermoperiod of 25/15C (77/59F) with constant light after imbibed seeds were maintained in total darkness for 0, 9, 18, 27, 36, 45, 54 or 63 days at the same temperatures. Maintenance of imbibed seeds of R. catawbiense in darkness at 25C (77F) for up to 63 days caused no induction of secondary dormancy while induction occurred for seeds in darkness at 25/15C (77/59F). When imbibed seeds of R. catawbiense were subjected immediately to light following imbibition, 30-day germination at 25C (77F) was 98% compared to 95% for imbibed seeds maintained in darkness for 63 days and then exposed to light. If germinated at 25/15C (77/59F), immediate light exposure resulted in 99% germination which decreased significantly to 76% after 63 days of dark treatment. Seeds of R. maximum maintained in darkness developed secondary dormancy at both temperatures. Thirty day germination of seeds subjected immediately to light following imbibition at 25C (77F) was 82% which decreased to 29% after dark treatment for 9 days. Further reductions in germination continued as the length of dark treatment increased with < 10% germination after maintenance in darkness for 27 days. At 25/15C (77/59F) induction of secondary dormancy was not as dramatic as that at 25C (77F). Without dark treatment, 30-day germination at 25/15C (77/59F) was 99% which decreased significantly to 88% after dark treatment for 18 days. Reductions in germination continued up to 63 days with 67% germination. Partial removal of secondary dormancy in seeds of R. maximum was achieved by subjecting seeds to moist-chilling.
Micronutrient Fertilization of Woody Seedlings Essential Regardless of Pine Bark pH
Authors: Wright Amy N. , Niemiera Alex X. , Harris J. Roger , Wright Robert D.
Published: August 2020

The objective of this study was to determine the effect of micronutrient amendments to pine bark on seedling growth over a wide pine bark pH range. Koelreuteria paniculata (Laxm.) was container-grown from seed in pine bark amended (preplant) with 0, 1.2, 2.4 or 3.6 kg/m3 (0, 2, 4, 6 lb/yd3) dolomitic limestone and 0 or 0.9 kg/m3 (1.5 lb/yd3) Micromax™ (micronutrient fertilizer). Initial pine bark pH for each lime rate was 4.0, 4.5, 5.0, and 5.5, respectively. Final pH (week 10) ranged from 4.7 to 6.4. Seedlings were harvested 10 weeks after planting and shoot dry mass and height determined. Pine bark solution was extracted using the pour-through method at 3, 7, and 10 weeks after planting. Solution pH was measured, and solutions were analyzed for Ca, Mg, Fe, Mn, Cu, and Zn. Shoot dry mass and height were greater in Micromax™ amended bark than in bark without Micromax™. Lime had no effect on shoot dry mass or height. In general, adding Micromax™ increased pine bark solution Ca, Mg, and micronutrient concentrations. Adding lime increased pine bark solution pH and Mg concentration and either had no effect on or decreased solution Ca and micronutrient concentrations. Regardless of pine bark pH, Micromax™ additions resulted in better growth, and adding lime was not necessary.
Assessment of New Fungicides for the Control of Southern Blight on Aucuba
Authors: Hagan A. K. , Olive J. W.
Published: August 2020

Drenches of Lynx 3.6F, ProStar 50W, Fluazinam 500F, Terraguard 50W, and Curalan DF were compared with Terraclor 75W for the control of southern blight on container-grown aucuba (Aucuba japonica) ‘Variegata’. Over the three-year test period, ProStar 50W and Fluazinam 500F across a range of rates completely protected aucuba from attack by the causal fungus, Sclerotium rolfsii. Also, both fungicides gave better disease control in two of three years than the current industry standard Terraclor 75W. Lynx 3.6F at the 0.54 g a.i./liter rate proved as effective in controlling southern blight as ProStar 50W and Fluazinam 500F. Terraclor 75W, which was applied at over twice the labeled drench rate, gave inconsistent disease control. Terraguard 50W and Curalan DF failed to provide effective control of southern blight on aucuba. No symptoms of phytotoxicity were observed.