bluuebunny/crossref_metadata_2025 huggingface dataset:
Susceptibility of Cornus Species to Two Genera of Powdery Mildew
Authors: Windham M.T. , Trigiano R.N. , Windham A.S.
Published: August 2020

Powdery mildew disease severity was assessed in fourteen species of Cornus. Seedlings of C. alternifolia, C. controversa and C. mas were not infected with powdery mildew. One cultivar of C. alba, ‘Bud's Yellow’, was also not infected, whereas ‘Ivory Halo’ was parasitized with Phyllactinia guttata. Cultivars of C. florida (‘Cherokee Brave’, ‘Cloud 9’, and ‘Cherokee Sunset’) and lines of C. kousa (seedlings and clones of C. kousa var. chinensis) significantly differed in their susceptibility to powdery mildew. All trees of C. florida and C. kousa had thalli and cleistothecia of Erysiphe pulchra on abaxial and adaxial surfaces. Location of mycelia and cleistothecia of P. guttata on leaves were variable for blue berry dogwood species.
Night-Interrupted Lighting Accelerates Flowering of Herbaceous Perennials Under Nursery Conditions in the Southern United States
Authors: Keever Gary J. , Raymond Kessler J. , Stephenson James C.
Published: August 2020

Night-interrupted lighting (NIL) outdoors in a southern nursery setting was evaluated as a system for accelerated production of herbaceous perennials requiring long days to flower. Treatments were NIL beginning February 1, February 15, March 1, or March 15, and a natural photoperiod control. Compared to plants under the natural photoperiod and depending upon initiation of NIL treatment and year, NIL accelerated and increased flowering of ‘Moonbeam’ coreopsis (Coreopsis verticillata L. ‘Moonbeam’) 7 to 36 days and 20 to 244%, ‘Early Sunrise’ coreopsis (Coreopsis grandiflora Hogg ex Sweet. ‘Early Sunrise’) 3 to 20 days and 26 to 64%, ‘Sunray’ coreopsis (Coreopsis grandiflora Hogg ex Sweet. ‘Sunray’) 6 to 13 days and 21 to 44%, ‘Autumn Joy’ stonecrop (Sedum x ‘Autumn Joy’) 26 to 57 days and 200 to 300%, and ‘Blue Queen’ salvia (Salvia x superba Stapf ‘Blue Queen’) 7 to 12 days and 56 to 83%. Flowering of ‘Red Beauty’ obedient plant (Physostegia virginiana (L.) Benth. ‘Red Beauty) was accelerated 20 to 54 days; however, inflorescence counts decreased 38 to 46% in one year and was not affected by treatments in the second year. Plants of all cultivars, except ‘Autumn Joy’ sedum and ‘Red Beauty’ obedient plant, were taller when exposed to NIL than when grown under the natural photoperiod, however plant quality rating of all cultivars was as high or higher under NIL.
Estimation of U.S. Bark Generation and Implications for Horticultural Industries
Authors: Lu Wenliang , Sibley Jeff L. , Gilliam Charles H. , Bannon James S. , Zhang Yaoqi
Published: August 2020

The historical, current, and projected supply of bark was evaluated. Since the 1980s more than 95 percent of the U.S. bark supply has been utilized in some way. Industrial fuel consumes the largest share of the market for bark, absorbing about 83 percent of softwood bark and 66 to 71 percent of hardwood bark. Current market share of bark for horticulture use (categorized in the miscellaneous group), is about 15 percent of softwood bark supply and about 30 percent of hardwood bark supply. In recent years, domestic timber harvest has been relatively stable or has slightly decreased. During the same time period, there has been an increasing demand for bark as an energy resource. Based on historical data, linear models were fitted between U.S. timber harvest and bark generation at the regional level. With those fitted models, projected bark generation was estimated based on the timber harvest data of the fifth Renewable Resources Planning Act (RPA) timber assessment. It is estimated that only a minor increase in the long term bark output will occur. For softwood bark which has the greatest demand, projected supply will be below the level of 2001 until about 2020. With expected horticulture industry growth, increased value of bark as a readily available energy source for wood processing mills, and a shift in pulp generation from domestic paper mills to international sources, the total amount and share of bark to the horticulture market will likely decrease.
Butterfly Feeding Preferences for Buddleja Selections in the Landscape
Authors: Bruner L.L. , Eakes D.J. , Keever G.J. , Baier J.W. , Stuart Whitman C. , Knight P.R. , Altland J.E.
Published: August 2020

In landscape studies conducted in 2002 and 2003, Buddleja davidii (Franch.) ‘White Profusion’, ‘Pink Delight’, and ‘Honeycomb’ were visited by native butterflies to a greater extent than to the remaining four Buddleja examined. In general, the lowest visitation was experienced by B. crispa (Benth.) and B. lindleyana (Fortune) ‘Miss Vicie’. Overall, B. davidii ‘Pink Delight’ was visited by the greatest number of species, while B. crispa and B. lindleyana ‘Miss Vicie’ were visited by the least. Total visit duration by one randomly selected butterfly was greater for B. davidii ‘White Profusion’, ‘Honeycomb’, ‘Pink Delight’, and ‘Royal Red’ in 2003, while no differences among cultivars were found in 2002. Differences in duration per visit were observed in 2003 with B. davidii ‘White Profusion’, ‘Pink Delight’, and ‘Royal Red’ having the greatest and B. crispa the least. Plant characteristics including inflorescence number, growth index, flower morphology, and flower color characteristics differed among cultivars. Through correlation analysis plant characteristics that contributed in part to cultivar differences in visitation were determined. Cultivar differences that consistently correlated with visitation preferences were inflorescence number and growth index. Based on correlation analysis, the cultivar characteristics that did not contribute to visitation differences included flower morphology and flower color characteristics.
Effect of Application Variables on Spray Deposition, Coverage, and Ground Losses in Nursery Tree Applications
Authors: Derksen Richard C. , Krause Charles R. , Fox Robert D. , Brazee Ross D. , Zondag Randy
Published: August 2020

An experimental cross-flow (CF) fan sprayer and a conventional, axial-fan (AF), orchard sprayer were used to treat multiple rows consisting of four year old, multi-stem, red maple trees, Acer rubrum L. and Turkish filbert trees, Corylus colurna L. The effects of sprayer type, fan orientation, application volume, and ground speed on canopy and ground spray deposits and canopy spray coverage across multiple target rows were evaluated. Variations in deposits and coverage across the canopies were generally smaller for the CF sprayer than the AF sprayer. The AF sprayer produced the highest overall deposits in the first row nearest the sprayer. Reducing fan speed kept more material in the tree row adjacent to the sprayer while decreasing spray volume did not affect the spray deposits in that row. Tower sprayer fan orientation did not affect canopy deposits but could be used to minimize spray drift. These results indicate that the most uniform spray distribution in a tree canopy is obtained by treating the canopy from each side. These findings also suggest growers should experiment with different spray volume and speed settings that can provide efficacious applications more efficiently.
Preemergence and Early Postemergence Control of Selected Container Nursery Weeds with BroadStar, OH2, and Snapshot TG
Authors: Judge Caren A. , Neal Joseph C.
Published: August 2020

Preemergence and early postemergence control of three common nursery weeds with BroadStar (flumioxazin), OH2 (oxyfluorfen + pendimethalin), and Snapshot TG (isoxaben + trifluralin) was compared in greenhouse and outdoor experiments. Hairy bittercress (Cardamine hirsuta), spotted spurge (Chamaesyce maculata), and common groundsel (Senecio vulgaris) were container-grown in the absence of ornamental crops and each herbicide was applied preemergence (labeled application) or postemergence to plants either at the cotyledon to one-leaf stage or at the two- to four-leaf stage. Each of the herbicides controlled hairy bittercress and spotted spurge preemergence and when applied to plants at the cotyledon to one-leaf stage. The herbicides were less effective on hairy bittercress and spotted spurge at the two- to four-leaf stage, yet control was 60 to 89%. Common groundsel was controlled preemergence by each herbicide; however, only BroadStar and OH2 controlled common groundsel ≥ 81% when applied at the cotyledon to one-leaf stage. No postemergence treatment controlled common groundsel when applied at the two-to four-leaf stage.
Herbicide-Treated Mulches for Weed Control in Nursery Container Crops
Authors: Case L.T. , Mathers H.M.
Published: August 2020

Weed control is the largest expense faced in the nursery and landscape industries. Nursery growers spend $967 to $2,228/A, depending on species, for supplemental hand weeding in addition to three to four yearly herbicide applications. Herbicide-treated mulches have utility in addressing many current nursery/landscape weed control issues such as non-target herbicide losses, leaching and off-site herbicide movement, and reduction of weed control costs. The objectives of this study were to compare seven types of mulches, including Douglas fir nuggets, pine nuggets, shredded hardwood, shredded Cypress, PennMulch™, rice hulls, and cocoa shells sprayed with Surflan [aqueous solution (AS) (oryzalin) at 1.12 (0.5×) and 2.24 (1×) kg ai/ha (1.0 and 2.0 lb ai/A)] and SureGuard [(water dispersible granular (WDG) (flumioxazin) at 0.19 (0.5×) and 0.38 (1×) kg ai/ha (0.17 and 0.34 lb ai/A)] to determine efficacy on common chickweed (Stellaria media), annual bluegrass (Poa annua) and spotted spurge (Chamaesyce humistrata) and phytotoxicity to Golden vicary privet (Ligustrum × vicaryi), creeping juniper (Juniperus horizontalis ‘P.C. Youngstown’), and wintergreen boxwood (Buxusmicrophylla ‘Wintergreen’) at 45 and 115 days after treatment (DAT). The herbicide-treated mulches were compared to untreated mulches, over-the-top sprays of the herbicides and a combination spray of Surflan + SureGuard each applied at the 1× rate, described above, an industry-standard granular formulation Rout (oxyfluorfen + oryzalin) at 3.41 kg ai/ha (3.0 lb ai/A), an industry standard nonchemical alternative Geodisc™, and an untreated control. The experiment was conducted in 2001 and repeated in 2002. In 2001, 17 of 43 treatments provided commercially acceptable visual ratings at 45 DAT; 14 were herbicide treated mulches. Four of five treatments in 2001 providing acceptable control at 115 DAT were herbicide treated mulches. In 2002, three treatments providing commercially acceptable control at 45 DAT were: PennMulch™ + 0.5 × Surflan, PennMulch™ + SureGuard, and Rout. Rout was the only treatment providing commercially acceptable control at 115 DAT in 2002. Golden vicary privet exhibited the greatest phytotoxicity in both years. In 2001-2002, the over-the-top sprays of Surflan + SureGuard were the most phytotoxic treatments to Golden vicary privet when averaged across 45 and 115 DAT. The data indicated a significant herbicide × mulch interaction and that some combinations, such as hardwood + SureGuard or pine nuggets + SureGuard, increased and extended efficacy and reduced phytotoxicity versus mulches or herbicides applied alone.
Substrate pH Suppression Using Incorporated Sulfur-based Compounds in Nursery Container Production
Authors: Giblin Chad P. , Gillman Jeffrey H.
Published: August 2020

Container production of ericaceous plants requires maintenance of a long-term substrate pH of 4.0 to 5.5. The objective of the study was to examine the effects of incorporated elemental sulfur, ferrous sulfate, and aluminum sulfate on long-term pH suppression in an acidic container substrate irrigated with highly alkaline water. ‘Northcountry’ blueberry liners were planted into a peat/pine bark based container substrate containing one of six different commercial amendments for pH reduction at three different rates of actual sulfur: 0.89 kg S/m3 (1.5 lb S/yd3), 1.78 kg S/m3 (3 lb S/yd3), and 2.67 kg S/m3 (4.5 lb. S/yd3). After fourteen weeks, only one elemental sulfur treatment had a substrate pH significantly lower than untreated substrate pH. Elemental sulfur particle size played a role in ability to control substrate pH.
Evaluating North and South Florida Landscape Performance and Fruiting of Ten Cultivars and a Wild-type Selection of Nandina domestica, a Potentially Invasive Shrub
Authors: Knox Gary W. , Wilson Sandra B.
Published: August 2020

A wild-type selection of heavenly bamboo (Nandina domestica) and ten cultivars were evaluated for plant performance, growth, flowering, and fruiting in north and south Florida. Onset of flowering generally began by March and April in south Florida and 4 to 8 weeks later in north Florida. Fruit was first noted 8 to 16 weeks after most selections began flowering. Landscape performance and fruit production varied widely among taxa and locations. The dwarf selections ‘Filamentosa’ and ‘Firepower’ failed to flower or fruit in either location; while the medium-sized selection, ‘Moon Bay’, did not flower or fruit in south Florida, and the medium-sized selection, ‘Gulf Stream’, flowered but did not fruit in south Florida. Large-sized selections produced more fruit than did dwarf and medium-sized cultivars. Greater plant survival with generally heavier fruiting was observed in north Florida than in south Florida. In north and south Florida, ‘Monum’ and ‘Compacta’ produced more fruit than did the wild-type selection. Seed viability was fairly consistent among cultivars, ranging from 73 to 86%.
Influence of Biostimulants and Water-Retaining Polymer Root Dips on Survival and Growth of Newly Transplanted Bare-Rooted Silver Birch and Rowan
Authors: Barnes Sally , Percival Glynn C
Published: August 2020

The influence of five commercially available biostimulant products (Trade names; Generate, Resistim, Fulcrum CRV, Bioplex, Maxicrop) in combination with a water-retaining polymer applied to the root system of silver birch (Betula pendula Roth.) and rowan (Sorbus aucuparia L.) during the winter period under field conditions was investigated. The short and long-term efficacy of biostimulants on growth was quantified by assessing root and shoot vigor and survival rates at week 8 and 20 post bud break. Improvements in tree vitality were also assessed by measurement of leaf photosynthetic rates, chlorophyll fluorescence emissions and chlorophyll content. Significant effects of species, biostimulant and concentration were found on the majority of growth and tree vitality parameters measured. Only two of the biostimulants tested induced significant growth responses in both tree species. Regardless of species, applications of a water retaining polymer alone had no significant effect on tree survival rates or tree vitality. However, growth of birch was significantly reduced compared to controls indicating a detrimental effect of polymer application alone on this species. Results conclude that use of commercially available biostimulant product in combination with a water retaining polymer can be of use to reduce transplant losses and improve tree vitality and growth over a growing season in silver birch and rowan. Selection of an appropriate biostimulant(s), however, is important as effects on growth and vitality varied widely between species and concentration of biostimulant applied.
Pendimethalin Influence on Azalea Shoot and Root Growth
Authors: Derr Jeffrey F. , Simmons Lori D.
Published: August 2020

Preemergence herbicides, especially members of the dinitroaniline class, are commonly applied to container-grown nursery stock. Dinitroaniline herbicides inhibit the development of new roots in susceptible plants, and can injure nursery crops. The effect of pendimethalin on root and shoot growth of ‘Tradition’ azalea was evaluated at 4 and 8 weeks after treatment. Pendimethalin was applied to azalea tops (shoot exposure), the growing medium (root exposure), or to the tops plus growing medium. Initial plant heights and root volumes were used to calculate percent increase in growth as affected by application method. Four weeks after treatment, plant height of shoot-only and shoot plus root treatments increased by 17 and 25%, respectively, while height in root-only and untreated control plots increased by 34%. Eight weeks after treatment (WAT), plant height of shoot-only and shoot plus root treatment increased by 61 and 63%, respectively, compared to root-only and untreated control plots, which increased by 105 and 108%, respectively. Greatest reductions in root growth were found in the shoot plus root and root-only treatments at 4 and 8 WAT, likely due to pendimethalin movement into the upper 3 cm of the growing mix. Pendimethalin can directly affect azalea shoot growth following exposure to only the foliage, and directly reduce root development following application to the growing medium. Any stunting of growth following over-the-top application of a sprayable pendimethalin formulation likely results from impacts on both the root and shoot systems.
Growth Stage and Time of the Year Effects on Nursery Crop Tolerance to Diuron
Authors: Simpson C.V. , Gilliam C.H. , Wehtje G.R. , Sibley J.L. , Altland J.E.
Published: August 2020

Four experiments were conducted to evaluate the tolerance of three landscape crops to over the top spray applications of diuron. Rates ≥ 0.56 kg ai/ha (0.5 lb ai/A) provided excellent (100%) yellow woodsorrel control regardless of the time of year the treatment was made. Diuron applications ≤ 1.12 kg ai/ha (1.0 lb ai/A) in fall and spring caused slight to no injury to dormant abelia, barberry, and spirea. Plants leafed out normally in the spring after application and there was no difference in growth 180 days after treatment (DAT). Application at 2.24 kg ai/ha (2.0 lb ai/A) caused slight to no injury on abelia, moderate injury to spirea, and severe injury to barberry by the following spring. Spring application to actively growing abelia and spirea caused slight to moderate injury from which plants treated with ≤ 0.56 kg ai/ha (0.5 lb ai/A) completely recovered by 90 DAT. Abelia treated with 1.12 kg ai/ha (1.0 lb ai/A) were slightly injured 90 DAT, and spirea were moderately injured 90 DAT. Abelia and spirea treated with 2.24 kg ai/ha (2.0 lb ai/A) were severely injured with many dead plants 60 DAT. Actively growing barberry treated with 0.28 kg ai/ha (0.25 lb ai/A) remained moderately injured by 90 DAT. Rates ≥ 0.56 kg ai/ha (0.5 lb ai/A) caused death to actively growing barberry by 60 DAT.
Growth Response of Crapemyrtle to Geographical Area and Production Light Level
Authors: Brooks K.M. , Keever G.J. , Altland J.E. , Sibley J.L.
Published: August 2020

The effects of geographic location and production light level on vegetative growth and flowering were evaluated as a means of accelerating the development of tree-form crapemyrtles. By the end of the first year of the experiment, Dynamite™, ‘Muskogee’, ‘Natchez’, and ‘Tuscarora’ grown in Oregon were as much as 42, 51, 43, and 92% taller, respectively, than plants in Alabama, while plants generally had less trunk diameter in Oregon. ‘Muskogee’ and ‘Natchez’ in both locations and ‘Tuscarora’ in Alabama were generally taller when grown under 50% shade than plants in full sun, while height of Dynamite™ was not affected by production light level. Trunk diameter of ‘Natchez’ in both locations and of Dynamite™ in Alabama was less when plants were grown under shade, while trunk diameter of ‘Muskogee’ and ‘Tuscarora’ was not affected by production light level. Flowering of plants grown under shade in Alabama was delayed, while no plants in Oregon flowered the first year. In the second year of the experiment when all plants were grown in full sun, all cultivars continued to be taller in Oregon, while trunk diameter remained greater in Alabama. The height advantage gained from growing plants under shade the previous year was not evident in any cultivar by the end of the second year, while trunk diameter was similar for all cultivars previously grown in full sun and under 50% shade. There was no difference in flowering of plants in Alabama previously grown under 50% shade and in full sun, while 50 to 100% of the four cultivars in Oregon flowered with no obvious difference due to prior production light level.
Cyclanilide Alterations In Growth Of Five Landscape Plant Species During Container Production Are Location Specific
Authors: Mackay Wayne A. , Arnold Michael A. , McDonald Garry V. , Sankhla Narendra
Published: August 2020

Five species of tropical and warm temperate shrubs, bush morning glory (Ipomoea carnea N. von Jacquin subsp. fistulosa (K. von Martinus ex J. Choisy) D. Austin), Indian hawthorn (Raphiolepis indica (L.) J. Lindley), tropical hibiscus (Hibiscus rosa-sinensis L. ‘Brilliantissima’), jatropha (Jatropha integerrima N. von Jacquin), and nandina (Nandina domestica C.P. Thunberg), were grown in 2.8-liter (#1) black plastic containers at two contrasting nursery locations and regimes. In College Station, TX, plants were grown in full sun under high fertility conditions, while in Dallas, TX, plants were grown under 40% light exclusion and a lower fertility level. Plants at each location were sprayed to runoff, either once or twice, with a distilled water only control, a Latron B-1956 spreader sticker surfactant at 0.063 mg/liter (0.063 ppm) in distilled water, or cyclanilide [1-(2,4-dichlorophenyaminocarbonyl)-cyclopropane carboxylic acid] at 56, 112, or 223 mg/liter (56, 112, or 223 ppm, respectively) with the Latron surfactant in a distilled water carrier. Half of the plants in all treatments received a single application, while the other half received a second application two to three weeks later. Although growth responses and release of dormancy varied among species and with cyclanilide concentration, plants of most species had greater release of lateral buds from a dormant or quiescent state under the high irradiance and fertility conditions in College Station, compared to the lower irradiance and fertility conditions in Dallas. However, phytotoxicity symptoms as evidenced by lower quality ratings were also more prevalent in College Station. Phytotoxicity was moderate to severe on nearly all jatropha and tropical hibiscus plants exposed to cyclanilide. Toxicity symptoms and significant growth reductions were present on several species at 112 or 223 mg/liter (112 or 223 ppm, respectively). A second application usually increased the effects on growth responses at all concentrations and often induced phytotoxicity symptoms at 56 mg/liter (56 ppm). The disparate responses between the two locations suggest the importance of local growing conditions on the potential efficacy and predictability of responses to cyclanilide applications.
Effect of Root-zone Temperature on Survival, Growth, and Root Morphology of Kalmia latifolia and Ilex crenata ‘Compacta’
Authors: Wright Amy N. , Warren Stuart L. , Blazich Frank A.
Published: August 2020

Root-zone temperature (RZT) is an important environmental factor affecting growth and performance of woody ornamental plants in the landscape. Research was conducted to compare the effects of RZT on survival, growth, and root morphology of a difficult-to-transplant species, mountain laurel (Kalmia latifolia L.), and an easy to transplant species, Japanese holly (Ilex crenata Thunb.). Seedlings of mountain laurel or micropropagated liners of mountain laurel (Kalmia latifolia L. ‘Sarah’) and rooted stem cuttings of Japanese holly (Ilex crenata Thunb. ‘Compacta’) were grown hydroponically for 12 weeks in controlled environment conditions under long days at 9-hr days/15-hr nights of 26/22C (79/72F) with RZTs of 16, 24, or 32C (61, 75, or 90F). Compared to 16 and 24C (61 and 75F), percent survival of mountain laurel was reduced by a RZT of 32C (90F), whereas percent survival of Compacta holly was unaffected by RZT. Root dry weight of mountain laurel was reduced 72% at 32C (90F) while top dry weight was unaffected by RZT. Top and root dry weights of Compacta holly were unaffected by RZT. Root: top ratio of mountain laurel was reduced by increasing RZT, whereas root: top ratio of Compacta holly was unaffected by RZT. Root area of mountain laurel and Compacta holly were reduced 80 and 64%, respectively, at 32C (90F) compared with 16C (61F). Number of lateral roots in the apical 2 cm (0.8 in) of primary roots of both taxa increased with increasing RZT. Results of this research indicate that reducing RZT in the landscape may increase survival and root growth of transplanted mountain laurel.
Efficacy of Non-Chemical Weed Control during Plug Establishment of a Wildflower Meadow
Authors: Watkinson Jonathon I. , Pill Wallace G.
Published: August 2020

The efficacy of non-chemical weed control during plug establishment of a wildflower meadow on glyphosate-killed turf grass was studied. Each field sub-block (not-tilled or twice-tilled to 15 cm (6 in) depth) on killed grass received the following sub-plot soil cover treatments: no cover, woven polypropylene weed fabric, double shredded hardwood/softwood mulch at 7.5 cm (3 in) depth, or fabric covered by mulch. Each 3 × 3 m (10 × 10 ft) subplot was planted in late spring with 100 plugs on 30 cm (1 ft) centers at the following frequency: Baptisia australis (10), Coreopsis lanceolata (20), Solidago speciosa (10), Panicum virgatum (20), and Schizachyrium scoparium (40). Tillage of the killed grass not only failed to benefit wildflower establishment, but increased weed shoot biomass during the second growing season. Greater wildflower shoot dry weights at 120 days after transplanting with mulch (with or without underlying fabric) than with fabric alone or no cover was associated with greater soil moisture, reduced soil temperature range, and reduced weed cover and shoot biomass. Weed fabric compared to no cover failed to affect wildflower shoot dry weights during either growing season but decreased weed growth during the second growing season. Fabric under mulch compared to mulch alone generally failed to affect wildflower growth and had no effect on weed growth during either growing season. During the second growing season, weed shoot dry weights remained low in mulched plots and remained high in non-mulched plots. Regardless of cover, wildflower shoots underwent considerable dry weight gain, while weed shoot dry weights generally remained constant or declined during the second growing season compared to the first. We conclude that, at least under our experimental conditions, applying a 7.5 cm (3 in) layer of wood chip mulch directly over glyphosate-killed turf was the most efficaceous and cost effective method of establishing a wildflower meadow using wildflower plugs. Neither placing weed fabric under the mulch nor twice-tilling the killed turf before mulch application benefitted wildflower shoot growth.
Efficacy of Metarhizium anisopliae as a Curative Application for Black Vine Weevil (Otiorhynchus sulcatus) Infesting Container-Grown Nursery Crops
Authors: Bruck Denny J.
Published: August 2020

The black vine weevil (BVW), Otiorhynchus sulcatus (F.) is a serious pest of nursery crops. The fungus, Metarhizium anisopliae (F52), is registered by the U.S. Environmental Protection Agency for BVW control. The objectives of this study were to determine the efficacy of a curative drench application of M. anisopliae for controlling BVW larval infestations in container-grown nursery plants and the effect of temperature on the rate of fungal growth and speed of kill. Trials evaluating the efficacy of M. anisopliae as a curative application were performed in the spring of 2004 and 2005 as well as the fall of 2006. Laboratory studies were performed to quantify the impact of temperature (10, 15, 20, 24 and 28C) on fungal growth and speed of kill. Metarhizium anisopliae applied in the greenhouse and outdoors in 2004 were 92 and 30% effective, respectively. Fungal applications to container-grown plant material maintained outdoors in the spring of 2005 were nearly 100% effective 28 days after application. Fall applications in 2006 provided statistically significant reductions in the number of live BVW larve per pot, but were not as effective as spring applications in 2005. The mean media temperature of containers maintained outdoors in the fall of 2006 dropped considerably (10–12C) over the course of the experiment and were likely the cause for the reduced efficacy. Laboratory experiments demonstrated that temperatures below 20C (68F) significantly slowed fungal growth and the speed at which M. anisopliae infected BVW larvae. In the field, drench applications of M. anisopliae were very effective at eliminating BVW larvae in container-grown nursery plants when media temperatures were adequate (> 15C (59F)). The use of M. anisopliae as a curative drench application has similar temperature-dependent limitations as the use of entomopathogenic nematodes for BVW control. Therefore, applications should occur as early in the fall as possible once egg laying has ended or in late spring just prior to pupation when media temperatures would be most conducive to fungal infection.
Synthetic and Biorational Fungicides Compared for the Control of Three Foliar Diseases of Flowering Dogwood
Authors: Hagan A.K. , Akridge J.R.
Published: August 2020

The biorational fungicides Neem Concentrate, SunSpray Ultra Fine Oil®, Rhapsody® were compared with the synthetic fungicides Eagle® 40W, Immunox®, Liquid Systemic Fungicide®, and 3336™ 50W for the control of spot anthracnose, Cercospora leaf spot, and powdery mildew on ‘Rubra’ flowering dogwood. In 2003, 2004, and 2005, fungicide treatments were applied at label rates at 1- and/or 2-week intervals over a period that coincided with the onset spot anthracnose and powdery mildew but before the appearance of Cercospora leaf spot. With few exceptions, the synthetic fungicides gave better control of the above diseases than biorational fungicides. Eagle 40W, Immunox, Liquid Systemic Fungicide, and 3336 50W gave equal control of the bract and leaf spot phases of spot anthracnose. Most notable was the carryover of control of the bract spot phase of spot anthracnose into the spring of the following year with the synthetic fungicides. While some control of spot anthracnose was seen in at least one year with the biorational fungicides, none was as effective as the synthetic fungicides. In 2003 and 2004, Neem Concentrate, SunSpray Ultra Fine Oil, and Rhapsody, when applied weekly controlled powdery mildew as effectively as the synthetic fungicides. Efficacy of the biorational fungicides declined under severe powdery mildew pressure in 2005. While Cercospora leaf spot development was slowed by the Eagle 40W, Liquid Systemic Fungicide, and 3336 50W, the biorational fungicides as well as the retail product Immunox also gave some control. An objectionable mottling of the leaves was noted on the flowering dogwood treated with SunSpray Ultra Fine Oil. Control of these diseases with the synthetic or biorational fungicides did not result in an increase in tree height or trunk diameter. While the biorational fungicides demonstrated sufficient efficacy for controlling powdery mildew on flowering dogwood in the landscape, they often failed to provide the level of control of this disease as well as spot anthracnose and Cercospora leaf spot needed to produce quality container- and field-grown nursery stock.
Growth and Landscape Performance of Ten Herbaceous Species in Response to Saline Water Irrigation
Authors: Niu Genhua , Rodriguez Denise S. , Aguiniga Lizzie
Published: August 2020

Ten herbaceous perennials and groundcovers were grown in raised beds from June to September in a dry, hot desert environment and micro-spray drip irrigated with synthesized saline solutions at electrical conductivity of 0.8 (tap water), 3.2, or 5.4 dS/m. Plant height and two perpendicular widths were recorded monthly to calculate the growth index. Landscape performance was assessed monthly by visual scores. Salinity did not affect the visual scores in Achillea millefolium L., Gaillardia aristata Pursh, Lantana x hybrida ‘New Gold’, Lonicera japonica Thunb. ‘Halliana’, and Rosmarinus officinalis L. ‘Huntington Carpet’ throughout the experiment. Glandularia canadensis (L.) Nutt. ‘Homestead Purple’ performed better than Glandularia x hybrida (Grönland & Rümpler) G. L. Nesom & Pruski. Lantana montevidensis (Spreng.) Brig. had lower visual scores at 5.4 dS/m compared to the control and 3.2 dS/m. Most plants of Rudbeckia hirta L. did not survive when irrigated at 3.2 dS/m or 5.4 dS/m. Shoot biomass of A. millefolium, G. aristata, L. x hybrida, L. japonica, R. officinalis, and V. macdougalii was not influenced by the salinity of irrigation water. Therefore, A. millefolium, G. aristata, L. x hybrida, L. japonica, and R. officinalis can be irrigated with non-potable water at salinity up to 5.4 dS/m with little reduction in growth and aesthetic appearance.
Cyclanilide Promotes Lateral Branching in Nursery Production of Woody Landscape Species
Authors: Banko Thomas J. , Stefani Marcia A.
Published: August 2020

During nursery production of landscape trees and shrubs it is desirable to promote the development of well-branched plants to achieve a uniform, full appearance. Branching may be promoted with multiple prunings but this is labor-intensive and expensive. In this study, spray applications of the bioregulator, cyclanilide (CYC), were evaluated for promotion of lateral branching on several container-grown landscape species. CYC spray concentrations of 0, 54, 106, and 212 ppm resulted in a linear increase in new lateral shoots for ‘Muskogee’ crape myrtle, ‘Pinkie’ and Eleanor Taber™ Indian hawthorn, and ‘Girard Rose’ azalea, and a quadratic increase in lateral shoots for ‘Compacta’ inkberry holly. Treatments to crape myrtle also caused a delay in flowering. CYC applications to Fraser photinia caused phytotoxic symptoms of leaf yellowing, blotching and curling, and increased susceptibility to entomosporium leaf spot.
Cyclanilide Spray Increases Branching in Containerized Whip Production
Authors: Sternberg Petra , Struve Daniel K.
Published: August 2020

A major goal in the production of tree whips is to produce appropriately sized, well-branched liners with a crown form similar to that of a mature tree. Pruning is used to induce lateral branching. This can result in poor tree quality, reduced growth and the practice is labor intensive. An alternative to mechanical pruning, foliar Cyclanilide® (CYC) sprays at 0, 56, 1 12 and 223 ppm were applied to container grown whips to determine its effect on branching of Amelanchier; Cercis, Malus and Tilia whips. Most species responded to CYC sprays with increased lateral branching if treated during active shoot elongation. Cyclanilide® sprays of 1 12 ppm produced the greatest number of branches. Sprays at 56 ppm resulted in reduced branching (relative to 112 ppm), while sprays of 223 ppm did not increase the number of branches, relative to sprays of 112 ppm, but reduced growth. Cyclanilide® sprays reduced height growth, relative to untreated whips, but did not alter height diameter growth. Cyclanilide® foliar applications to container -grown whips during periods of active shoot elongation increased branching in one-year-old whips that normally do not branch until the second year of production. Further, the origin of lateral branching can be controlled by timing of CYC application. The results indicate that CYC foliar sprays can be an important tool in the production of one-year-old branched whips.
Impact of Mulches on Landscape Plants and the Environment — A Review
Authors: Chalker-Scott Linda
Published: August 2020

Mulches provide aesthetic, economic and environmental benefits to urban landscapes. Mulching is especially useful in the establishment of trees in landscapes that receive minimal care, such as restoration sites. In general, mulches improve soil health, creating healthy populations of plants and associated animals. These biodiverse, stable landscapes are more resistant to stress, are more aesthetically pleasing, require fewer applications of pesticides and fertilizers, and are ultimately more sustainable than those without mulch cover. All mulches are not created equally, however, and this review compares the costs and benefits of landscape mulches as reported in the scientific literature. It also presents real and perceived problems associated with various landscape mulches.
Cyclanilide Foliar Applications Induce Greater Lateral Branching than Pruning in Container-Grown Whips
Authors: Sternberg Petra , Struve Daniel K.
Published: August 2020

A major goal in the production of ornamental whips is to produce small well-branched liners with a crown form similar to that of a mature tree. Pruning is used to induce lateral branching and regulate height. Pruning may result in poor tree quality, reduced whip growth and is labor intensive. This study was done to determine the effects of foliar Cyclanilide (CYC) applications with and without pruning on branching in container grown whips. Four taxa were used: Diospyros virginiana L., Eucommia ulmoides Oliv., Malus × ‘Prairie Fire’ and Tilia cordata ‘Greenspire’. In a two factorial experiment, CYC concentrations of 0, 50 and 100 ppm were applied to Diospyros and Eucommia (2005) and 0, 56 and 112 ppm to Malus and Tilia (2006), with half of the whips of each species receiving terminal shoot pruning, the remaining whips were left intact. Pruning reduced whip height in two out of four species tested. Cyclanilide sprays significantly increased branching and reduced height in Malus and Tilia whips. An interaction between CYC sprays and terminal shoot pruning occurred with branching in Tilia. Here, the combination of CYC spray and terminal shoot pruning significantly reduced the number of new lateral branches compared to CYC sprays alone. Overall CYC was more successful in inducing branching than terminal shoot pruning, but failed to induce branching in the strongly decurrent species Eucommia. Cyclanilide sprays are a more effective method for inducing branching and reducing height than terminal shoot pruning, but the combination of both, as done in this experiment, is not recommended.
Influence of Spray Volume on Spray Deposition and Coverage within Nursery Trees
Authors: Zhu H. , Zondag R.H. , Derksen R.C. , Reding M. , Krause C.R.
Published: August 2020

Information on better utilizing airblast sprayers to achieve high pesticide spray application efficiency in nursery tree production is needed. Foliar spray deposition and coverage at different heights inside crabapple tree canopies were investigated for a conventional airblast sprayer operating at four different application rates ranging from 230 to 900 liters/ha [24 to 94 gallons per acre (GPA)]. Deposition on the ground at various distances from the sprayer was also measured at the 700 liters/ha (73 GPA) application rate. Foliar deposition and coverage on targets below 2.6 m (8.5 ft) inside tree canopies increased as the application rate increased, but the increase in the coverage was much lower than the deposition. For trees taller than 2.6 m (8.5 ft), the sprayer could not deliver uniform spray deposition and coverage across the tree height. The portion of trees below 2.1 m (6.9 ft) was well covered by the spray deposits with 230 liters/ha (24 GPA) application rate while higher application rates resulted in over spray application. Less than 30% of total spray volume was deposited on target trees while over 34% of the total spray volume was lost on the ground. The tree-row volume method should include foliage density and tree-row gaps to avoid excessive estimation of spray application rates for nursery tree crops.
Postharvest Longevity and Viability of Cooler-stored Lotus Propagules
Authors: Tian Daike , Tilt Ken M. , Woods Floyd M. , Raymond Kessler J. , Sibley Jeff L.
Published: August 2020

Storage of enlarged lotus rhizomes used as a vegetable crop has been extensively studied, but little is known about the viability of lotus propagules (rhizomes with shoots) during storage. In this study, ornamental lotus, Nelumbo nucifera ‘Embolene’, was used to evaluate the effects of gum acacia, sphagnum moss and Terra-Sorb® hydrogel on the physiology and postharvest longevity or viability of stored lotus propagules. After 45 days of storage at 5C (42F) and 95% RH, there were no decayed propagules, and 94% of total propagules maintained their viability after planting. Water retention and shelf-life of rhizomes were similar among all treatments during storage. However, more water loss occurred with treatments at higher concentrations of gum acacia. After harvest, large differences in total sugar were found among individual samples, while starch content remained unchanged. A strong quadratic relationship was observed between total sugar and storage time for all treatments, but there was no significant effect of treatment on total carbohydrate change in lotus propagules after 45 days of storage.
Consumer Preferences for Native Plants in Montana Residential Landscapes and Perceptions for Naturalistic Designs
Authors: Zadegan Yousef R. , Behe Bridget K. , Gough Robert
Published: August 2020

In a preliminary study, consumer perceptions of native plants in traditional and naturalistic settings was investigated. In Montana, 361 participants in an internet study reported their familiarity with both woody and herbaceous native plant species. Additional data were collected to determine their perceptions of native plants used in naturalistic designs through a conjoint study. Nearly half of the study participants recognized or had purchased most of the native plants shown in photographs. Results of the conjoint study showed that participants placed the greatest relative importance (62%) on landscape style as the most important factor in landscape design. They also preferred a naturalistic style over a more traditional style and mixed plant species to single species. Across all comparisons, the high relative importance of landscape style remained constant and was consistent with prior studies. Plant material (21.9%) and species diversity (16.2%) were half the relative importance of design style and remained relatively consistent through most comparisons. Even among those participants not familiar with native plants and those who had not purchased native plants, native plants were preferred in the landscapes. The demand for native plants may be reaching a critical stage for both commercial growers and the landscape profession. Although this study was limited to one state, results show that consumer interest is present and further investigation is warranted.
Paclobutrazol Effects on Bedding Plants During Production, Shipping, and the Retail Environment When Applied in Production
Authors: Keever G.J. , Kessler J.R.
Published: August 2020

Foliar sprays of 10, 15, or 20 ppm paclobutrazol followed by a second application of 50 ppm were applied to ‘Bravo Lavender’ and ‘Celebrity Blue’ petunias and ‘Salvador Red’ and ‘Vista Red’ salvia during production to determine their effects on plant growth, flowering and market quality during production, simulated shipping, and while in a simulated retail environment. Paclobutrazol effectively suppressed shoot growth and enhanced market quality of all cultivars during production, while minimally or not affecting time to first flower. Growth suppression and enhanced market quality continued through simulated shipping and the period plants were in the retail environment. While in the simulated retail environment, plants were exposed to six or seven wilt/hydration cycles. The % wilted plants of all four cultivars previously treated with paclobutrazol during production was much less than that of the controls: ‘Bravo Lavender’ petunia, 21 vs. 67%; ‘Celebrity Blue’ petunia, 10 vs. 88%; ‘Salvador Red’ salvia, 15 vs. 69%; and ‘Vista Red’ salvia; 13 vs. 74%.
Effects of Fall Fertilization on Freeze Resistance, Flowering, and Growth of ‘Hinodegiri’ Azalea
Authors: Henning Frank P. , Smalley Timothy J. , Lindstrom Orville M. , Ruter John M.
Published: August 2020

Five fertigation treatments were initiated August 1, 2002: 1) no additional fertilizer, 2) N at 75 mg·L−1 from August 1 to September 29, 3) N at 125 mg·L−1 from August 1 to September 29, 4) N at 75 mg·L−1 from August 1 to November 28, and 5) N at 125 mg·L−1 from August 1 to November 28. Freeze resistance of stems and leaves was analyzed monthly, November to February. Flower counts began prior to budbreak, and continued to flower expression. Fall fertigation increased azalea leaf and stem dry weights (DWs) compared to azaleas that received no additional fertigation after July 31. Fertigation N applied at 75 or 125 mg·L−1 from August 1 to November 28 did not increase leaf or stem DWs compared to plants fertigated at the same N rate from August 1 to September 29. High N treatments (N at 125 mg·L−1 from August 1 to September 29 or November 28) increased above ground DW, but reduced stem freeze resistance in November and March compared to plants that received N at 75 mg·L−1 from August 1 to September 29. Early flower budbreak and decreased total flower production resulted when N was applied at 125 mg·L−1 from August 1 to November 28 compared to 75 mg·L−1 from August 1 to September 29.
Nursery Container Weed Control with Pinebark Mininuggets
Authors: Richardson Ben , Gilliam Charles H. , Fain Glenn , Wehtje Glenn
Published: August 2020

The market for large plants is increasing steadily; however, weed control in large containers present new production problems for growers. Experiments were conducted to evaluate pine bark mini-nuggets for weed control in 11 and 27 liter (#3 and #7) containers. In October 2004, Gardenia jasminoides (August Beauty gardenia) were seeded with oxalis, and Lagerstroemia indica ‘Natchez’ (crapemyrtle) with bittercress in 27 liter (#7) containers. In March 2005, Hydrangea quercifolia (oakleaf hydrangea) were seeded with oxalis and Ternstroemia gymnanthera (ternstroemia) with bittercress in 11 liter (#3) containers. Treatments consisted of mulch applied at depths of 0, 3.8, and 7.6 cm (0, 1.5 and 3.0 in), with seed applied either above or below the mulch. A separate group of treatments were included similar to the above except that a granular preemergence herbicide was applied after mulch application. Growth of crapemyrtle and ternstroemia were similar regardless of mulch depth. With gardenia and oakleaf hydrangea growth differences existed but there were no consistent trends among treatments. Season long weed control was obtained in all treatments that included 7.6 cm (3.0 in) mulch depth.
Optimum Nitrogen Fertilization for Production of Containerized Raphiolepis × delacourii ‘Snow White’
Authors: Tillman Amy L. , Warren Stuart L. , Blazich Frank A.
Published: August 2020

Rooted stem cuttings of ‘Snow White’ raphiolepis (Raphiolepis × delacourii Andre ‘Snow White’) were grown in 3.8-liter (#1) black plastic containers containing a pine bark:sand (8:1, by vol) substrate. Plants were fertilized at every irrigation, for 17 weeks, with a 4:1:2 nitrogen (N):phosphorus (P):potassium (K) nutrient solution containing N at 20, 60, 100, 140, 180, 220, or 240 mg·L−1 (ppm) supplied as ammonium nitrate (NH4NO3). Maximum top and root dry weights were achieved with N at 145 mg·L−1. Substrate solution electrical conductivity increased linearly with increasing nitrogen application rate (NAR) with maximum growth occurring at 1.28 dS·m−1, whereas substrate solution pH decreased linearly with increasing NAR with a pH of 5.3 at 145 mg·L−1. Increasing the N rate beyond 145 mg·L−1 had minimal effect on top or root dry weight. Leaf area peaked at a NAR of 171 mg·L−1 with a plateau at 524 cm2. Leaf area increased 275% as the NAR increased from 20 to 171 mg·L−1. Specific leaf area increased linearly with increasing NARs. Carbon allocation between tops and roots was unaffected by NARs from 60 to 280 mg·L−1. Root:top ratio decreased 56% between the pooled NARs (60 to 240 mg·L−1) and N at 20 mg·L−1. Leaf area ratio increased linearly with increasing NARs. Foliar mineral nutrient concentrations of N, P, and sulfur increased linearly with increasing NAR, whereas concentrations of K, calcium, magnesium, and copper responded quadratically to increasing NARs. Top growth increased from inadequate at a NAR of 60 mg·L−1 to optimum at 145 mg·L−1, whereas root growth was relatively similar over the same range. At 145 mg·L−1, mineral nutrient concentrations of the top are well within or exceed accepted levels reported, and growers can expect rapid growth of rooted cuttings.