bluuebunny/crossref_metadata_2025 huggingface dataset:
Consequences of Excessive Overhead Irrigation on Runoff during Container Production of Sweet Viburnum
Authors: Million Jeff , Yeager Tom , Albano Joseph
Published: August 2020

The effects of irrigation rate on volume and nutrient content of runoff were investigated. Runoff (leachate plus un-intercepted irrigation and rain) was collected weekly for 20 weeks during production of trade #1 (2.7-liter) sweet viburnum [Viburnum odoratissimum (L.) Ker-Gawl.] fertilized with a resin-coated, controlled-release fertilizer [Osmocote 18N–2.6P–10K (18–6–12), 8–9 month 21C (70F)]. Treatments were a factorial arrangement of two irrigation rates [1 (IRR1) or 2 (IRR2) cm/day (0.39 or 0.79 in)] and two fertilizer rates [15 (FRT15) or 30 (FRT30) g/container (0.53 or 1.06 oz)]. Total runoff volume was 970 liters/m2 (2380 gal/100 ft2) for IRR1 and 2220 liters/m2 (5450 gal/100 ft2) for IRR2 which was 49 and 69%, respectively, of total irrigation plus rainfall. Increasing the irrigation rate from 1 to 2 cm/day increased leaching losses of N, P, and K 34, 38, and 45%, respectively, with FRT15 and 21, 28, and 23%, respectively, with FRT30. Increasing the irrigation rate increased nutrient loads (g/m2) but decreased nutrient concentrations (mg/liter) in runoff.
Feeding Preferences of Dogwood Sawfly Larvae Indicate Resistance in Cornus
Authors: Klingeman W. E. , Chen F. , Kim H. J. , Flanagan P. C.
Published: August 2020

Dogwood sawfly (Macremphytus tarsatus Say) is a native, phytophagous insect that relies on Cornus sp. host plants for larval development. Feeding injury by dogwood sawflies is primarily aesthetic and seldom results in host plant death. Still, native and non-native dogwoods have not been evaluated for susceptibility to larval feeding by this aesthetically damaging wasp. Ten species or cultivars of dogwoods that are either naturalized native plants or economically significant landscape plants were assayed for host suitability to dogwood sawfly larvae in no-choice and choice experiments. Flowering, kousa and corneliancherry dogwoods were consistently ranked among the least susceptible host plants while ‘Sibirica’ tatarian, gray, and ‘Flaviramea’ golden-twig dogwoods were highly preferred hosts. Preliminary GC/MS comparisons of foliar metabolite extracts from all 10 species have identified five peaks of interest that varied between resistant and susceptible hosts. These results suggest that certain chemical constituents in foliage of dogwood species may be important predictors of host palatability. More research is needed to confirm this hypothesis before crossbreeding for sawfly resistance can proceed.
Methods of Auxin Application in Cutting Propagation: A Review of 70 Years of Scientific Discovery and Commercial Practice
Authors: Blythe Eugene K. , Sibley Jeff L. , Tilt Ken M. , Ruter John M.
Published: August 2020

The discovery of auxins as plant growth regulating chemicals in the 1930s and their ability to stimulate adventitious rooting in stem cuttings marked a major milestone in the modern history of plant propagation. Basic and applied research conducted during the past 70 years has provided information regarding absorption and translocation of auxin in cuttings, as well as the effects of timing of auxin application, methods of auxin application, type of auxin, and concentration of auxin on the rooting response of cuttings. The basal quick-dip method, the powder application method, and the dilute soak method have been the most commonly used methods for applying auxin to cuttings in commercial horticulture over the past 7 decades, with the first two methods still in common use today. In addition, a wide variety of other auxin application methods have been reported beginning in the 1930s and continuing to the present. Some of these methods remain primarily of historical interest, several find limited use in commercial horticulture, and others show potential for greater use in the future. Opportunities exist for further development of auxin application techniques that can enhance plant quality, efficiency and productivity of the cutting propagation process, and worker safety. This review provides horticulturists, from the academic researcher to the commercial propagator, with an exploration of auxin application methods over the past 70 years, along with an examination of the physiological response of cuttings to applied auxin and an overview of issues leading to future opportunities.
Effect of Preemergence Herbicides on the Cold Hardiness of Container-grown Kurume Hybrid Azalea (Rhododendron x hybrida ‘Tradition’)
Authors: Czarnota M.A. , Lindstrom O.M.
Published: August 2020

Since there is considerable use of preemergence herbicides in the containerized nursery industry, a study was conducted to determine if they affect the ability of plants to cold acclimate. Six preemergence herbicides with different modes-of-action were chosen for the study, and were applied to a Kurume type azalea (Rhododendron x hybrida ‘Tradition’) on October 8, 2004. Laboratory cold hardiness evaluations were conducted at 10, 17, and 24 weeks after treatment (WAT) to both stems and leaves. None of the preemergent herbicides tested caused a significant trend in cold acclimation with either stems or leaves when compared over all sampling dates and temperatures. However, some preemergence herbicides caused a significant increase or decrease in cold acclimation of stems and leaves at selected sampling dates and temperatures.
Plant Growth Retardants Affect Growth and Flowering of Coreopsis verticillata ‘Moonbeam’
Authors: Kessler J.R. , Keever G.J.
Published: August 2020

This investigation was conducted to determine the plant growth retardant type, application method, and rate required to produce a marketable greenhouse pot plant of Coreopsis verticillata L. ‘Moonbeam’. Pruned plants in 10 cm (4 in) pots received growth retardant treatments in two experiments consisting of one application of ancymidol or paclobutrazol medium drenches at 0, 2, 4, or 6 ppm; daminozide spray at 0, 2550, 5100, or 7650 ppm; paclobutrazol spray at 0, 12, 24, 36, 48, or 60 ppm; flurprimidol spray at 0, 25, 50, 75, 100, 150, or 200 ppm; or maleic hydrazide at 0, 360, 720, 1080, 1440, or 1800 ppm in the first experiment and sprays of daminozide at 0, 2550, 5100, or 7650 ppm; paclobutrazol at 0, 60, or 120 ppm; daminozide/paclobutrazol combinations at 0, 2550/16, 2550/32, 2550/48, or 2550/64 ppm, chloromequat at 0, 767, 1534, or 2301 ppm; or daminozide/chloromequat combinations at 0, 1275/1534, 2550/1534, 3825/1534, or 5100/1534 ppm in the second experiment. In the first experiment, there was a linear decrease in shoot height, growth index, and lateral shoot length with increasing rates of ancymidol and paclobutrazol drenches and flurprimidol sprays while daminozide decreased growth quadratically. There was a linear increase in shoot height and lateral shoot length with increasing rates of maleic hydrazide but no effect on growth index. Only daminozide and maleic hydrazide increased the number of days from treatment to flower with increasing rates. Quality ratings increased with increasing rates of ancymidol, daminozide, and flurprimidol with the highest ratings found at the two highest rates of daminozide and flurprimidol. Paclobutrazol spray did not affect the parameters measured. In the second experiment, chloromequat spray did not affect the parameters measured but when combined with increasing rates of daminozide, linearly decreased shoot height, growth index, and lateral shoot length while increasing the number of days to flower. Daminozide alone resulted in a quadratic change in growth index and lateral shoot length while linearly increasing the number of days to flower but with no effect on quality rating. The higher rates of paclobutrazol than were used in the first experiment decreased shoot height and lateral shoot length with no effect on growth index, the number of days to flower, or quality rating. Overall, the best quality ratings and the most compact plants resulted from spray applications of daminozide at 5100 ppm or 7650 ppm and flurprimidol at 150 ppm or 200 ppm, however flurprimidol is not currently registered for application to greenhouse crops but a newer product, Topflor, has the same active ingredient and greenhouse crop labeling.
Influence of Container Mulches on Irrigation and Nutrient Management
Authors: Altland James , Lanthier Mario
Published: August 2020

An experiment was conducted in 2005 and repeated in 2006 to determine the influence of mulch products and controlled release fertilizer (CRF) placement on irrigation and nutrition requirements of container-grown crops. Hydrangea (Hydrangea macrophylla ‘Fasan’ and ‘Endless Summer’) were grown in 2.7 liter (#1) containers with CRF placed above or below the mulch. Non-mulched controls were also maintained. Mulch products included geotextile discs, coco discs, plastic discs, hazelnut shells, sawdust, Biotop, and crumb rubber. Hydrangea growth, plant quality, foliar color, and foliar nutrition were measured, as well as water loss from containers. Controlled release fertilizer placed below mulch resulted in larger plants with higher quality ratings and foliar N levels compared to CRF placed above the mulch, and similar or superior size, quality and foliar N compared to non-mulched containers. After correcting for differences in plant size, there were few and minor differences in water loss from hydrangea between mulched and non-mulched containers.
Improving Early Field Growth of Leyland Cypress Liners by Grading and Potting
Authors: Eric Hinesley L. , Blazich Frank A.
Published: August 2020

Stem cuttings of Leyland cypress [Callitropsis × leylandii (A. B. Jacks. & Dallim.) D. P. Little; syn. × Cupressocyparis leylandii (A. B. Jacks. & Dallim.) Dallim. & A. B. Jacks.] were rooted beginning May 2004. In February 2005, liners were sorted into four grades [1 = firm root ball, top to bottom, 2 = good root ball, but loose in the upper one-third; 3 = no distinct root ball, but with enough roots to survive when potted and grown in irrigated containers; and 4 = roots ≤ 2 cm (0.8 in) in length (discarded)]. Liners from Grades 1 and 2 were transplanted to the field April 2005. Additional liners of Grades 1, 2, and 3 were grown in 3.8-liter (1-gal) containers in a nursery during 2005, and field planted early September 2005. Height and stem diameter were recorded after 1 and 2 years. Containerizing affected stem diameter more than height. Growth during the first 2 years was proportional to initial size, indicating the benefits of grading. After 2 years, the largest plants were Grade 1 liners that went directly to the field April 2005, with no intermediate potting.
Growth Control of ‘Taylortown Red’ and ‘Homestead Purple’ Verbena with Pistill in Nursery Production
Authors: Banko T.J. , Stefani M.A.
Published: August 2020

Verbena canadensis ‘Homestead Purple’ and ‘Taylortown Red’ were treated with one or two spray applications of the plant growth regulator (PGR) Pistill (ethephon) at 0, 250, 500, 750, or 1000 ppm. Plants were in 3.8 liter (1 gal) containers under outdoor nursery conditions. Plant widths of ‘Homestead Purple’ verbena were suppressed linearly with increasing Pistill concentrations up to 24% at 2 weeks after initial treatment (WAT) and up to 18% at 4 WAT. Widths of ‘Taylortown Red’ verbena were suppressed 22% at 2 WAT with a single application at 500 to 1000 ppm, and linearly up to 33% at 4 WAT with 2 applications. Two applications of Pistill suppressed heights and widths of both cultivars at 7 WAT compared to one application.
Seed Germination of Two Populations of Rhododendron vaseyi: Influence of Light and Temperature
Authors: LeBude Anthony V. , Blazich Frank A. , Walker Lela C. , Robinson Sonya M.
Published: August 2020

Seeds of two populations of Rhododendron vaseyi A. Gray (pinkshell azalea) were germinated at 25C (77F) or an 8/16 hr thermoperiod of 30/20C (86/68F) with daily photoperiods at each temperature of 0 (total darkness), ½, 1, 2, 4, 8, 12, or 24 hr. Germination was recorded every 3 days for 30 days. Light was required for germination regardless of population or temperature. As photoperiod increased, germination increased. The highest cumulative (30-day) germination percentages were realized at 30/20C with a 24-hr photoperiod; germination percentages for populations 1 and 2 were 45 and 50%, respectively. Temperature and photoperiod requirements for germination did not generally differ between the two populations.
Total Phenolic Content of Asian Elm Leaves and Host Plant Suitability for Gypsy Moth
Authors: Paluch Gretchen , Miller Fredric , Zhu Junwei , Coats Joel
Published: August 2020

The total phenolic content of foliage from 11 elm species and 2 cultivars was measured, and the relationship to gypsy moth developmental studies was determined. The 13 elms, Ulmus wilsoniana (Schneid.), U. japonica (Rehd.), U. glaucesens (Franch), ‘Accolade’, ‘Triumph’, U. davidiana (Planch), U. parvifolia (Jacq.), U. szechuanica (Fang), U. macrocarpa (Hance), U. chenmoui (Cheng), U. lamellosa (C. Wang et S.L. Chang, ex L.K. Fu), U. castaneifolia (Hemsl.), and U. gaussenii (Cheng), were grown at the Morton Arboretum, Lisle, IL and analyzed at the Pesticide Toxicology Laboratory, Iowa State University, Ames, IA. Significant differences were found in the phenolic content of the 13 elms surveyed. No significant differences were identified between gypsy moth larval longevity, pupal fresh weight, or percentage adult emergence with respect to total leaf phenolic content.
Influence of Irrigation Regime on Growth of Select Field-grown Tree Species in a Semi-arid Climate
Authors: Fox Lindsey , Montague Thayne
Published: August 2020

Over three growing seasons (2003 through 2005) we investigated stem area increase and shoot growth of field-grown (FG) trident maple (Acer buergeranum), hedge maple (A. campestre), autumn blaze maple (A. × freemanii ‘Autumn Blaze’), shantung maple (A. truncatum), Mexican redbud (Cercis canadensis mexicana), Texas redbud (C. canadensis texensis), white Texas redbud (C. canadensis texensis ‘Alba’), Oklahoma redbud (C. canadensis texensis ‘Oklahoma’), Washington hawthorn (Crataegus phaenopyrum), Arizona ash (Fraxinus velutina coriacea ‘Bonita’), Mexican plum (Prunus mexicana), chinquapin oak (Quercus muehlenbergii), English oak (Q. robur) trees subjected to three reference evapotranspiration (ETo) based irrigation regimes (100, 60, and 30% ETo). For maple trees, stem area increase did not differ between irrigation treatments. However, except for trident maple shoot elongation varied with irrigation level and species. Stem area did not differ between irrigation regimes for redbud trees, and shoot elongation was generally greatest for trees that received lower irrigation treatments. Depending upon species, oak stem area increase did not differ, or was greatest for trees that received greater irrigation. For each oak species, shoot elongation was influenced by irrigation level. For two of the three remaining species, stem area increase and shoot elongation differed according to irrigation volume. Despite three differing irrigation volumes, greatest growth was not always associated with increased irrigation volume. In addition, each species appears to be suited for regions with low precipitation and high pH soils.
Evaluation of Composted Poultry Litter as a Substrate Amendment for WholeTree, Clean Chip Residual, and Pinebark for Container Grown Woody Nursery Crops
Authors: Marble Stephen C. , Gilliam Charles H. , Sibley Jeff L. , Fain Glenn B. , Allen Torbert H. , Gallagher Tom V. , Olive John W.
Published: August 2020

WholeTree (WT) and clean chip residual (CCR) are potential new nursery substrates that are by-products of the forestry industry containing high wood content. Initial immobilization of nitrogen is one concern when using these new substrates; however the addition of composted poultry litter (CPL) to substrates containing high wood content could balance initial nitrogen immobilization and provide an inexpensive fertilizer source for growers. This study evaluated five woody nursery species being grown in WT, CCR, and pinebark (PB) with the addition of CPL or peat as a substrate amendment. Results indicate that these species can be grown successfully in WT and CCR substrates 6: 1 (by vol) with CPL. Use of CPL in WT and CCR substrates may provide an alternative to traditional PB plus peat based combinations in container plant production while providing poultry producers an environmentally sound means of waste disposal.
Vegetative Propagation of Oconee Azalea (Rhododendron flammeum) by Stem Cuttings and Mound Layering
Authors: Jones Jeff R. , LeBude Anthony V. , Ranney Thomas G.
Published: August 2020

Deciduous azaleas (Rhododendron L.) offer a range of desirable ornamental characteristics and can be valuable nursery crops. Availability in the nursery trade, however, can be limited by the lack of effective propagation protocols. Therefore, the objectives of this research were to develop and optimize vegetative propagation protocols for Oconee azalea, Rhododendron flammeum (Michx.) Sarg., utilizing stem cuttings or in-field mound layering. An optimal method for producing rooted stem cuttings with large root systems (> 20 cm2) was to collect softwood stem cuttings from hedged stock plants followed by treatment with 10,000 ppm of the potassium salt (K-salt) of indolebutyric acid (K-IBA). Mound layering was also effective. Fifty percent of the stems on each mound resulted in rooted layers and approximately six layers were produced per mound regardless of mounding season (March or June), with or without wounding, or application of 5000 ppm K-IBA to stems prior to mounding in June. Both softwood cuttings and mound layering can be utilized to produce high quality plants.
Growth Retardant Use on Herbaceous Perennials Grown Under Night-Interrupted Lighting Outdoors in the Southern United States
Authors: Keever Gary J. , Kessler J. Raymond , Stephenson James C.
Published: August 2020

A study was conducted in 2002 and 2003 to determine if growth retardants could be used to suppress stem elongation of ‘Moonbeam’ coreopsis (Coreopsis verticillata L. ‘Moonbeam’) and ‘Goldsturm’ coneflower (Rudbeckia fulgida Aiton ‘Goldsturm’) when grown outdoors under nursery conditions in the southern United States without negating the benefits of earlier flowering from night-interrupted lighting (NIL). Night-interrupted lighting accelerated flowering of both cultivars without adversely affecting flower and flower bud counts or plant quality. However, plants grown under NIL generally were taller than plants grown under natural photoperiod (NP). When several PGRs [Cutless, B-Nine, B-Nine/Cycocel, Bonzi (2002 only), and Sumagic (2003 only)] were applied to plants under NIL, results varied with PGR type and concentration and year. Height of ‘Moonbeam’ coreopsis was effectively suppressed by 5000 or 7500 ppm B-Nine + 1500 ppm Cycocel in both years of the study and with 40 or 60 ppm Sumagic in the one year it was tested. Higher concentrations of Cutless and B-Nine suppressed height growth in 1 of 2 years, while Bonzi was ineffective. None of the PGR types or concentrations suppressed height growth of ‘Goldsturm’ coneflower to the level of the NP control in 2002. However, in 2003 when an additional application of Cutless and B-Nine were made, and Bonzi was replaced with Sumagic, applications of Cutless, B-Nine, B-Nine/Cycocel, and Sumagic all resulted in heights similar to or less than that of plants under NP with minimal effects on time to flower or flower and flower bud counts.
Response of Five Hydrangea Species to Foliar Salt Spray
Authors: Barbara Conolly N. , Bassuk Nina L. , MacRae Patrick F.
Published: August 2020

Hydrangeas are popular seaside plants; however, other than in anecdotal reports, there are no studies measuring their relative tolerance to salt spray. We examined response of ten cultivars and one subspecies of Hydrangea representing five species to foliar-applied salt solutions to recommend selections for seaside landscapes. Objectives were to determine whether there are differences in responses to salt spray among cultivars and species, and to determine whether varying concentrations of sodium chloride differentially damaged the plants. Plants were treated with a full-strength (ion concentration approximate to seawater) salt solution, a half-strength salt solution, or a control of tap water. Plants were rated after seven once-weekly applications based on percentage necrotic leaf area, an aesthetically and physiologically important symptom of damage. Cultivars of Hydrangea macrophylla and Hydrangea serrata were more tolerant of full-strength salt spray than cultivars of H. paniculata, H. anomala and H. arborescens. At half strength but not full strength, H. anomala ssp. petiolaris was most tolerant. Hydrangea macrophylla and H. serrata were the second most tolerant of half-strength applications. Hydrangea macrophylla or Hydrangea serrata should be planted where maritime salt spray will occur.
Cyclanilide Differentially Affects Branching in Red Maple Cultivars and Hybrids
Authors: Mickelbart Michael V.
Published: August 2020

Development of the canopy is an important aspect of ornamental shade tree production. Branching can be induced by pruning the apical meristem, but this process is time consuming and costly to growers. Cyclanilide is an auxin transport inhibitor that has been successfully used to eliminate apical dominance and increase branching in a number of tree species. In this study, we tested the effects of cyclanilide application in two years on branching, canopy form, and trunk diameter. Cyclanilide did not cause phytotoxicity symptoms in any cultivar at any rate. Two cultivars, Celebration® (Acer × freemanii A.E. Murray ‘Celzam’) and Sienna Glen® (Acer × freemanii ‘Sienna’) Freeman maples responded to cyclanilide treatments with increased primary and secondary shoots, whereas Red Sunset® red maple (Acer rubrum L. ‘Franksred’) and Autumn Blaze® Freeman maple (Acer × freemanii A.E. Murray ‘Jeffersred’) did not respond to any treatments. Responsive cultivars had approximately double the number of growing points and larger total branch length after second year applications, but this did not result in an increase in trunk caliper. Despite the increased number of shoots produced, overall canopy ratings did not differ among treatments. Cyclanilide had a limited affect on branching in red and Freeman maple whips. Furthermore, if growers choose to utilize this product, they should be aware that cultivar response is likely to vary, and initial testing should be done before making large-scale applications.
Host Plant Relationships of Leptodictya plana (Hemiptera: Tingidae)
Authors: Carr E. R. , Braman S. K. , Hanna W. W.
Published: August 2020

Leptodictya plana Heidemann is an emerging pest on ornamental grasses in the southern United States. Thirty-two selections of commercially available ornamental grasses and sedges and five trial accessions of Pennisetum purpureum were evaluated for susceptibility to L. plana feeding and oviposition. No-choice studies were conducted in a greenhouse by securing four lace bugs to leaf blades of each plant using clip cages. Lace bugs stayed attached for five days. Damage and number eggs were recorded. Choice studies were conducted in the laboratory by placing leaf blades from each genus of plant species into a large petri dish in a spoke pattern. There were no plants tested that consistently received zero percent damage in either trial. Plants that sustained the least damage included Acorus spp., Cordyline spp., and Panicum spp. Pennisetum spp. entries exhibited the highest overall percent damage and were the only genera of plants that supported oviposition.
Late Fall and Early Spring Application of Granular Preemergence Herbicide on a Fertilizer Carrier for Season-Long Crabgrass Control
Authors: Reicher Zachary J. , Weisenberger Daniel V. , Melichar Michael W. , Loughner Daniel L. , Borger Jeffrey A. , Naedel Matthew B.
Published: August 2020

Though sprayable preemergence herbicides will provide season-long control of crabgrass when applied in fall or early spring in the northern states, little work has been done with the now popular granular formulations of preemergence herbicide on a fertilizer carrier. Dimension (dithiopyr) or Barricade (prodiamine) on a fertilizer carrier were applied in October, November, March, April, May, or June in three trials and crabgrass control was monitored the summer following application. A single granular application of 0.56 kg ai·ha−1 (0.5 lb ai·A−1) of Dimension in November or March can provide control equivalent to that expected from typical mid-April applications. Barricade at 0.72 kg ai·ha−1 (0.65 lb ai·A−1) applied in November or March provided season-long crabgrass control equivalent to traditional mid-April application timing, though season-long crabgrass control from a November application of Barricade at 0.72 kg ai·ha−1 (0.65 lb ai·A−1) can be improved by a sequential May application of 0.28 kg ai·ha−1 (0.25 lb ai·A−1). Adding a sequential May application of Dimension at 0.28 kg ai·ha−1 (0.25 lb ai·A−1) only minimally improved crabgrass control over a November Dimension application at 0.56 kg ai·ha−1 (0.5 lb ai·A−1). Granular formulations of preemergence herbicide on a fertilizer carrier applied in November or March can provide season-long control similar to when applied at the traditional timing in mid-April in the Midwest and Mid-Atlantic regions of the United States. However, it is important for season-long crabgrass control to use the high label rate or follow with a sequential application in early summer if lower rates are used in the fall.
Impact of Overseeded Grass Species, Seeding Rate and Seeding Time on Establishment and Persistence in Bermudagrass
Authors: Serensits Thomas , Cutulle Matthew , Derr Jeffrey F.
Published: August 2020

Cool-season grass species are often overseeded into bermudagrass turf for both aesthetics and functionality during the winter months. When the overseeded grass persists beyond the spring, however, it becomes a weed. Experiments were conducted to evaluate overseeded grass species and seeding rate on turf cover during the fall, spring, and summer. The ability of perennial ryegrass, Italian ryegrass, and hybrid bluegrass to then persist in bermudagrass one year after seeding was determined. Both perennial ryegrass and Italian ryegrass produced acceptable ground cover in the spring after fall seeding. Hybrid bluegrass did not establish well, resulting in unacceptable cover. Perennial ryegrass generally had the most persistence one year after seeding, either because of the survival of plants through the summer or because of new germination the following fall. The highest cover seen one year after seeding was 24% with perennial ryegrass in the 2005 trial. Maximum cover seen with Italian ryegrass and hybrid bluegrass 12 months after seeding was 19 and 8%, respectively. Seeding perennial or Italian ryegrass in February achieved acceptable cover in spring in the first trial but not the second. Persistence the following fall, however, was greater in the second trial, suggesting new germination. Percent cover 12 months after seeding tended to increase as the seeding rate increased, also suggesting new germination the following fall. Although quality is lower with Italian ryegrass compared to perennial ryegrass, it transitions out easier than perennial ryegrass, resulting in fewer surviving plants one year after fall seeding.
Cold Tolerance of Shade Tree Species and Cultivars in the Upper Midwest
Authors: Pellett H. , Moe S. , Vogel K.
Published: August 2020

Evaluation of shade tree species and cultivars for adaptability to Minnesota climatic conditions was initiated in 1978. Evaluation includes cultivars of Acer platanoides, Acer rubrum, Acer saccharinum, Acer saccharum, Fraxinus americana, Fraxinus pennsylvanica, Ginkgo biloba, Gleditsia triacanthos inermis, Tilia americana, Tilia cordata, and other shade tree species. Plantings were established at the University of Minnesota Landscape Arboretum, Chanhassen, MN. The severe winter of 1983–84 was especially damaging to clones' of Acer platanoides. Survival data are given for plants under evaluation.
Evaluation of a Substrate-applied Humectant to Mitigate Drought Stress in Young, Container-grown Plants
Authors: Roberts Bruce R. , Wolverton Chris , West Samantha
Published: August 2020

The efficacy of treating soilless substrate with a commercial humectant was tested as a means of suppressing drought stress in 4-week-old container-grown Zinnia elegans Jacq. ‘Thumbelina’. The humectant was applied as a substrate amendment at concentrations of 0.0, 0.8, 1.6 and 3.2% by volume prior to withholding irrigation. An untreated, well-watered control was also included. The substrate of treated plants was allowed to dry until the foliage wilted, at which time the plants were harvested and the following measurements taken: number of days to wilt (DTW), xylem water potential (ψx), shoot growth (shoot dry weight, leaf area) and root growth (length, diameter, surface area, volume, dry weight). For drought-stressed plants grown in humectant-treated substrate at concentrations of 1.6 and 3.2%, DTW increased 25 and 33%, respectively. A linear decrease in ψx was observed as the concentration of humectant increased from 0.0 to 3.2%. Linear trends were also noted for both volumetric moisture content (positive) and evapotranspiration (negative) as the concentration of humectant increased. For non-irrigated, untreated plants, stress inhibited shoot growth more than root growth, resulting in a lower root:shoot ratio. For non-irrigated, humectant-treated plants, the length of fine, water-absorbing roots increased linearly as humectant concentration increased from 0.0 to 3.2%. Using humectant-amended substrates may be a management option for mitigating the symptoms of drought stress during the production of container-grown bedding plants such as Z. elegans.
Impact of Fertilization on Vinca (Catharanthus roseus L.) Grown in Binary Mixtures of Sugarcane Filter Press Mud and Vermiculite
Authors: Larsen Nicholas A. , Moore Kimberly A.
Published: August 2020

Filter press mud (FPM) is a waste product of the sugar manufacturing industry that is primarily composed of soil, finely ground sugarcane (Saccharum spp.) stalks, and lime. It is widely used as a soil amendment wherever sugarcane is produced. This study sought to investigate the impact of fertilization with potassium nitrate on the growth of vinca (Cataranthus roseus L.) being grown in mixtures of FPM and vermiculite. The purpose of the study was to investigate the nutrient-supplying ability of the FPM-based growing medium. A completely randomized factorial design was installed into 18-count landscape trays, with each cell consisting of a different growing medium by fertilization treatment. While the bulk density of FPM-based growing media tended to be higher than FafardTM 2, plant growth was not stunted. Electrical conductivity and pH were not deleterious to the plants in any of the FPM treatments. Fertilization increased plant growth and development in all treatments in comparison to non-fertilized controls. The 1:1 FPM and vermiculite mixture by volume had the greatest increase in growth from fertilization while the least change in growth from fertilization occurred with the 100 percent FPM treatment. When using FPM as a growing medium, it appears that the fertilization practices might be decreased to take advantage of the nutrients released by the growing medium.
Japanese Maple Scale Activity and Management in Field Nursery Production
Authors: Addesso K.M. , Blalock A. , O'Neal P.A.
Published: August 2020

Japanese maple scale, Lopholeucaspis japonica Cockerell (Hemiptera: Diaspididae), is an armored scale found on the bark of many woody nursery and landscape plants. Scale crawler and male flight activity was monitored in middle Tennessee in fields of cherry (Prunus serrulata Lindl. ‘Kwanzan’) for two seasons. Two generations of crawlers were observed, with a large peak of activity in late May and a second, less pronounced peak in August. Male flights occurred twice a year, in April and July. Spray and drench applications of insecticides were trialed in 2014 and 2015. Dormant oil applications reduced overwintering scale populations by 76%. Drench applications of imidacloprid in 2014 suppressed scale populations by 58% by four months following application and the following summer those same trees had no observable scale infestation. Summer trunk applications of pyriproxyfen were effective at managing scale crawlers while horticultural oil alone had no measurable effect. When scale populations were high at the outset of spring 2014, a dinotefuran drench application was ineffective after 90 days. Dinotefuran gave greater control in 2015 when scale populations were low prior to application. Based on these results, a multiple component program for field management of Japanese maple scale is recommended.
Impact of Application Temperature on Broadleaf Herbicide Efficacy
Authors: Derr Jeffrey , Serensits Thomas
Published: August 2020

Cold air temperatures at the time of herbicide application are generally thought to decrease efficacy of systemic herbicides. Contact herbicides such as carfentrazone and sulfentrazone combined with systemic herbicides may provide an increased level of weed control when applied at cold air temperatures compared to products containing only systemic ones. Identical herbicide treatments were made at air temperatures of approximately 7 C (45 F) and 18 C (65 F) in four different trials. Control of ivyleaf speedwell, common chickweed, henbit, purple deadnettle, and white clover was evaluated. In general, warm temperature applications initially provided better weed control during the first week after treatment (WAT). By 2 to 3 WAT though, air temperature at the time of application generally did not affect overall weed control. In study 1, at 56 days after treatment (DAT) regardless of air temperature at application, all tested herbicides provided 86% or greater control of ivyleaf speedwell (Veronica hederifolia L.), and 98% or greater control of henbit (Lamium amplexicaule L.), with the exception of Trimec Classic, which did not provide acceptable control of henbit. Common chickweed (Stellaria media L.) control with combination treatments containing carfentrazone or sulfentrazone was similar at both temperature regimes, with control of 95% or greater, averaged across application air temperature. In study 2, after higher initial control with warm temperature treatments during the first WAT, Powerzone and Speedzone provided the highest level of control of ivyleaf speedwell and purple deadnettle at 35 DAT with no difference noted between air temperatures at application. Control of ivyleaf speedwell and purple deadnettle (Lamium purpureum L.) with Powerzone was 85 and 82%, respectively, averaged across temperature applications, while Speedzone controlled these two weed species 88 and 92%, respectively. In general, herbicides evaluated provided similar weed control at approximately 50 DAT when applied at warm or cold temperatures. Only for common chickweed control in trial 3 was there a significant interaction between temperature and herbicide treatment when evaluated 50 DAT. In that study, Speedzone and Trimec Classic gave greater control at warm compared to cold temperature application. Herbicides containing carfentrazone plus ester forms of 2,4-D or MCPA provided the highest levels of control.
The impact of substrate and irrigation interval on the post-transplant root growth of container-grown zinnia and tomato1
Authors: Roberts Bruce R. , Wolverton Chris , Janowicz Lauren
Published: August 2020

Substrate type and irrigation interval were studied to determine their impact on the post-transplant root growth of ‘Thumbelina' zinnia (Zinnis elegans Jacq.) and ‘Celebrity Hybrid' tomato (Lycopersicon esculentum Mill.). Seeds of both species were planted in 80 cm3 (2.7 fl oz) plug cells containing either Metromix 360™ (MM360) or Ball Professional Growing Mix™ (BPGM) and, following germination, the seedlings were transplanted into 450 cm3 (27.5 in3) plastic pots containing the same substrate. Evapotranspiration (ETO) was measured gravimetrically each day and the water lost via ETO added back to the substrate at intervals of 24, 48 or 96hr. For zinnia, root growth was consistently better for seedlings grown in BPGM, a substrate with greater water holding capacity and air-filled porosity. For plants grown in BPGM and irrigated every 48hr, root dry weight was significantly greater than it was for any of the remaining treatments. For tomato, root growth was greater for seedlings grown in BPGM and for transplants irrigated at 96 hr intervals; but, unlike zinnia, no significant interactions between substrate type and irrigation interval were observed. The results of this study show that root growth of plug-grown transplants can be improved by selecting a substrate with high porosity that allows for optimum oxygen and water exchange, and by extending the irrigation cycle to 48 hr (zinnia) or 96 hr (tomato).

Index words: irrigation scheduling, moisture stress, plant establishment, soilless growing media, transplant production

Species used in this study: ‘Thumbelina' zinnia (Zinnia elegans Jacq.); ‘Celebrity Hybrid' (Lycopersicon esculentum Mill.).
Decision Support Systems for Plant Disease and Insect Management in Commercial Nurseries in the Midwest: A Perspective Review1
Authors: Wallhead Matthew , Zhu Heping
Published: August 2020

Decision-support systems (DSS) are techniques that help decision makers utilize models to solve problems under complex and uncertain conditions. Predicting conditions that warrant intervention is a key tenet of the concept of integrated pest management (IPM) with the use of expert systems and pest models being characteristics of higher-level IPM. In this paper, potentials of four DSS including Ag-Radar, NEWA, RIMpro and Skybit to be used for ornamental nursery production are discussed. These systems were previously developed for orchard growers to effectively manage plant diseases and insects. Their development was based on the input of historical disease, insect pest and weather information. It will be an instrumental management aid to control insects and diseases in a timely manner if nursery growers can adaptively implement these orchard DSS into their production practices. In order to maximize effectiveness, however, next-generation DSS should consider the addition of consensus forecast models into user interfaces by combining the information generated from multiple independent models into a single spray-decision recommendation.

Index words: expert system, DSS, model prediction, forecast, insect, disease.
Poultry Litter Ash Rate and Placement Affect Phosphorus Dissolution in a Horticultural Substrate1
Authors: Wells Daniel E. , Beasley Jeffrey S. , Bush Edward W. , Gaston Lewis. A.
Published: August 2020

Poultry litter ash (PLA) is a byproduct of bioenergy production and an effective P source for horticultural crops since it reduces P losses from container production due to its low P solubility. Experiments were conducted to determine effects of rate and placement of PLA on P loss from greenhouse crop production and growth and quality of two commonly-grown greenhouse crops, Verbena canadensis Britton ‘Homestead Purple' and Lantana camara L. ‘New Gold', by comparing two rates (140 and 280 g·m−3 P or 0.4 and 0.8 lb·yd−3) and two application methods (post-plant topdressed and pre-plant incorporated). Leachate-dissolved reactive phosphorus (DRP) concentrations were reduced by an average of 24% as P rate was reduced from 280 to 140 g·m−3, but were 134% less on average when PLA was topdressed instead of incorporated. Foliar P concentrations were less 33% and 44% for verbena and lantana, respectively when plants were topdressed compared to incorporated. Shoot biomass of verbena and lantana was 9% and 24% greater, respectively, when incorporating instead of topdressing PLA. As a P source, PLA should be pre-plant incorporated within the substrate at a total P rate between 140 g·m−3 (0.4 lb·yd−3) and 280 g·m−3 (0.8 lb·yd−3).

Index words: phosphorus, poultry litter ash, Verbena canadensis Britton ‘Homestead Purple', Lantana camara L. ‘New Gold', dissolved reactive phosphorus.

Species used in this study: ‘Homestead Purple' verbena (Verbena canadensis Britton); ‘New Gold' lantana (Lantana camara L.).
Comparing Closed Chamber Measures of Ammonia Volatilization from Kentucky Bluegrass Fertilized by Granular Urea1
Authors: Schlossberg Maxim J. , McGraw Benjamin A. , Hivner Kyle R.
Published: August 2020

Easy handling and low unit N cost make prilled urea (46-0-0) a popular fertilizer. While incomplete recovery of granular urea applications by turfgrass is documented, practical guidance for small-plot field assessment of ammonia (NH3) volatilization remains limited. Our objectives were to (i) develop a method for field-implementation of closed flux/dynamic chambers to measure ammonia emission over a 3-day period following granular urea application to turfgrass, and (ii) infer the significance of said measures to levels arising from simultaneous static-chamber measures. A Kentucky bluegrass (Poa pratensis L. ‘Midnight’) lawn was treated with granular urea-N at a rate of 0 or 43 kg.ha−1 (38 lb/A) twice in both 2014 and 2015. Flux chamber measures of mean ammonia volatilization from urea-N fertilizer applied 3 days previous exceeded simultaneous static chamber measures by a factor of 17. Relative to static, the closed dynamic/flux chamber system described affords a more precise and efficient method for measuring ammonia volatilization from small field plots. Furthermore, over a 3-day period of dry conditions and ambient temperatures fluctuating between 10 and 31 C (50 and 88 F), as much as 23.1% of a granular urea application broadcast over a Kentucky bluegrass lawn can be volatilized as ammonia.

Index words: flux, gaseous emissions, methods, nitrogen, static, turfgrass.

Species used in this study: ‘Midnight' Kentucky bluegrass (Poa pratensis L.).
Green Lacewings and Water Sprays for Azalea Lace Bug Control1
Authors: Lee Jana C. , Finley Barry , Flores S. Michael , Graham Katerina Velasco , Woltz J. Megan , Wong Jessica S. , Rosetta Robin
Published: August 2020

The azalea lace bug, Stephanitis pyrioides, is a serious pest of azaleas and rhododendrons which is often controlled by systemic insecticides. However, the efficacy of softer approaches such as biological control and water sprays against this pest on rhododendrons is unknown. Therefore, we tested the commercially available green lacewing predator, Chrysoperla rufilabris, and water sprays on lace bug infestation in one laboratory and four field trials. First, 2nd instar predator larvae were confirmed to consume lace bug nymphs and sometimes adults. Second, tapping predator larvae from hexcel units over dry leaves of potted rhododendrons and shaking loose eggs over wet leaves were reliable application methods. Third, predator larvae released onto potted rhododendrons lowered lace bug counts for two weeks. Fourth, after four bi-weekly applications, plants receiving egg cards or water-sprays had reduced lace bug counts and fewer damaged leaves than control plants. Fifth, landscape plants receiving the sequential combination of water spray followed by predator egg releases had 44 to 90% lower lace bug abundance and fewer damaged leaves than the control. After lace bugs were initially dislodged, hatching predators might have consumed hatching lace bugs.

Index words: biological control, Chrysoperla rufilabris (Burmeister), mechanical control, rhododendron, Stephanitis pyrioides (Scott)

Species used in this study: Azalea lace bug (Stephanitis pyrioides Scott), green lacewing (Chrysoperla rufilabris Burmeister), Rhododendron (Rhododendron spp.)
Effects of Biochar on Nutrient Leaching and Begonia Plant Growth1
Authors: Crutchfield Elizabeth F. , McGiffen Milton E. , Merhaut Donald J.
Published: August 2020

Biochar is a highly adsorptive carbon substrate. A study was conducted to determine the ability of biochar to reduce fertilizer runoff from nurseries. Potting mix was augmented with biochar at different rates, ranging from 0% to 30% by volume, with some treatments planted with Begonia x semperflorens-cultorum hort. ‘Viva.' The pots were fertilized with a modified Hoagland solution and watered four times a week. The leachate was collected from each pot after watering and aggregated into weekly samples. Leachate from each week was analyzed photometrically for nitrate, ammonium and ortho-phosphate concentrations. Leaching of all three ions was reduced in the biochar-amended treatments. Biochar did not affect plant growth, nitrogen or phosphorus content of the plant material.

Index words: Ammonium nitrate, phosphate, biochar, begonia, Begonia x semperflorens-cultorum hort. ‘Viva,' media, container production

Species used: Begonia x semperflorens-cultorum hort. ‘Viva'
Production of Thuja (T. standishii x T. plicata) Using an Automated Micro-Irrigation System and Routine Leaching Fraction Testing in a Container Nursery1
Authors: Million Jeff B. , Yeager Thomas H.
Published: August 2020

A web-based, container irrigation scheduling program (CIRRIG) based on routine Leaching Fraction (LF=drainage/applied) testing and real-time weather monitoring was evaluated for its effect on plant growth and water use of Thuja (T. standishii x T. plicata) ‘Green Giant' in #15 [43 cm (17 inch)] containers in a commercial nursery in Florida. Independently-controlled irrigation zones each containing 830 plants were irrigated automatically with CIRRIG or with the nursery's traditional irrigation practice of a fixed daily rate. After 6 months, CIRRIG reduced the total volume of water applied by 51% [490 vs. 990 L/plant (129 vs. 262 gal/plant) but reduced growth in plant height and width by 15% and 10%, respectively. Routine LF testing indicated that the target LF of 25% was likely too low for the coarse pine bark substrate and spray-stake irrigation system. In light of stricter consumptive use permitting of water by governmental agencies, technologies such as CIRRIG may allow nurseries to produce more plants with less water.

Index words: CIRRIG, evapotranspiration, growth, landscape plant, programmable logic controller, water use

Species used in this study: Thuja Green Giant [Thuja (T. standishii x T. plicata) ‘Green Giant']
An Update of the Literature Supporting the Well-Being Benefits of Plants: A Review of the Emotional and Mental Health Benefits of Plants
Authors: Hall Charles , Knuth Melinda
Published: August 2020

Consumers have historically shown an inclination to purchase plants that enhance their quality of life, meaning they will purchase items that positively influence their social, physical, psychological, cognitive, environmental, and spiritual well-being. Plants in native and improved landscapes (and interiorscapes) have been documented to influence each of six quality of life constructs. This paper summarizes publications regarding the emotional and mental health benefits associated with plants, addressing reduced anxiety and stress, attention deficit recovery, fractals and visual response, decreased depression, enhanced memory retention, greater happiness and life satisfaction, mitigation of post-traumatic stress disorder (PTSD), increased creativity, enhanced productivity and attention, reduced effects of dementia, and improved self-esteem. This research should be strategically incorporated into both industry-wide and firm-specific marketing messages that highlight the quality of life value proposition in order to maintain the industry's sense of value and relevance to consumers of the future.

Index words: benefits of plants, emotional health, mental health.