bluuebunny/crossref_metadata_2025 huggingface dataset:
Spray Delivery to Nursery Trees by Air Curtain and Axial Fan Orchard Sprayers
Authors: Derksen Richard C. , Krause Charles R. , Fox Robert D. , Brazee Ross D. , Zondag Randy
Published: August 2020

Two types of air-assist sprayers were used to treat, from one side only, a single row of hedge-pruned, red maple (Acer rubrum L. ‘Red Sunset’) trees in a commercial Ohio nursery. A traditional orchard type sprayer and a prototype air curtain sprayer using crossflow fans and hydraulic nozzles were evaluated for differences in canopy deposits, spray coverage, and downwind ground deposits. The air curtain sprayer produced more uniform deposits vertically but not higher mean deposits than the traditional orchard type sprayer. The air curtain sprayer also produced somewhat higher ground deposits downwind of the treatment area. There were no differences in spray coverage between sprayers despite differences in the droplet spectrum produced by each sprayer. Evidence from the coverage and ground target samples indicate that slower fans on the air curtain sprayer might be needed to reduce air speed to retain more spray within the tree canopy. As operated, neither of the sprayers can be expected to produce uniform spray deposits around the nursery stock if treatments are made from one side of the row only. Canopy and ground target deposits indicate that alternate row spraying will not necessarily produce uniform deposits across two tree rows as planted at the test site.
Fall Subsurface Insecticide Treatments Control European Chafer Grubs Damaging Field-Grown Nursery Crops
Authors: Reding Michael E. , Klein Michael G. , Brazee Ross D. , Krause Charles R.
Published: August 2020

Third instar European chafer (EC), Rhizotrogus majalis (Razoumowsky), were found to be killing field-grown Rhododendrons ‘P.J.M.’ and Eastern hemlocks in two commercial nurseries in northeastern Ohio. Apparently, 1 or 2 grubs per plant were sufficient to severely damage young plants (rhododendrons). Subsurface applications of Dursban TNP were tested as rescue treatments against the grubs in these fields. Three novel single-point subsurface applicators were tested for delivery of Dursban in the rhododendron trial. A subsurface treatment of Dursban TNP was compared to surface applied drench treatments of Dursban TNP and Dylox 80 T & O in the hemlock trial. We found that EC grubs killed young plants of both species by removing most of the fibrous roots and/or girdling the stems. The subsurface treatments of Dursban TNP, significantly reduced (95%) the number of EC grubs compared to untreated hemlocks and rhododendrons when treatments were applied early or late fall, respectively. There were no differences in suppression of grubs among the applicators in the rhododendron trial.
Evaluation of Nutrient Phosphite for the Control of Phytophthora Shoot Blight on Annual Vinca
Authors: Banko T.J. , Hong C.X.
Published: August 2020

Annual vinca (Catharanthus roseus) were grown in containers in a greenhouse and irrigated with a complete nutrient solution containing phosphite (0, 0.1, 0.3 mM), phosphate (0, 0.3, 0.5 mM), or combinations of these two compounds as a source of phosphorus. After 2 weeks, the plants were sprayed with a Phytophthora nicotianae zoospore inoculum to evaluate the potential for phosphite to protect annual vinca from Phytophthora shoot blight. To determine the extent and duration of protection from shoot blight provided by phosphite foliar applications, the plants were treated with phosphite foliar sprays (0.5 mM) at various intervals, and then inoculated. Application of phosphite to the soil/roots provided no protection from Phytophthora shoot blight. However, foliar applications of phosphite at a concentration of 0.5 mM at three to six day intervals gave protection similar to foliar applications of Aliette fungicide at 3 g/liter (2.5 lb/100 gal) applied at 14 day intervals.
Nursery Floor Affects Containerized Plant Growth
Authors: Warren Stuart L. , Bilderback Ted E.
Published: August 2020

Rooted stem cuttings of ‘Skogholm’ cotoneaster (Cotoneaster dammeri ‘Skogholm’) potted into 14.2 liter (#5) containers in a pine bark: sand substrate were used to determine the effects of the nursery floor on plant growth, water use efficiency, substrate and plant canopy temperature, winter protection, and mineral nutrient efficacy. Four nursery floors were evaluated: black plastic, black ground fabric over black plastic, white plastic, and gravel from May 10, 2001, to April 23, 2002. Plants grown on gravel or ground fabric/black plastic had greater top and root dry weights compared to plants grown on white plastic. Water use efficiency was similar across all nursery floors, requiring an average 391 ml (13.2 oz) of water to produce a gram (0.04 oz) of plant material. Net photosynthetic rates of plants grown on black plastic, gravel, or ground fabric/black plastic were significantly greater than cotoneaster grown on white plastic. Plants grown on white plastic had significantly higher plant canopy [1 to 2C (1.8 to 3.6F)] and substrate temperatures [1 to 4C (1.8 to 7.2F)] daily from 1000 HR to 2000 HR throughout the summer months compared to all other nursery floors. Plant canopy and substrate temperatures were unaffected by the nursery floor during the winter months. Nitrogen efficiency was 42% on ground fabric/black plastic, 40% on gravel, 37% on black plastic and 33% on white plastic. Phosphorus efficiency was 53% on gravel, 52% on ground fabric/black plastic, 49% on black plastic and 43% on white plastic.
Seasonal Effects of Transplanting on Northern Red Oak and Willow Oak
Authors: Richardson-Calfee Lisa E. , Harris J. Roger , Fanelli Jody K.
Published: August 2020

Seasonal effects on transplant establishment of balled-and-burlapped (B&B) shade trees are not well documented. Early post-transplant root growth and aboveground growth over a 3-year period were therefore determined for November-and March-transplanted northern red oak (Quercus rubra L.) and willow oak (Q. phellos L.). Survival of red oak was 100% for both treatments. Survival of November-and March-transplanted willow oak was 67% and 83%, respectively. No new root growth was observed outside or within the root balls of either species upon excavation in January. New root growth was evident when trees of both species were excavated in April, indicating that root system regeneration of November-transplanted trees occurs in late winter and/or early spring, not late fall and/or early winter. November-transplanted red oak, but not willow oak, grew more roots by spring bud break than March-transplanted trees. However, little difference in height growth and trunk expansion was evident between the November-and March-transplanted red oaks throughout the 3 years following transplant. While height growth of willow oak was nearly identical between treatments after 3 years, November transplants exhibited greater trunk diameter increase for all 3 years. Overall, season of transplant had little effect on height and trunk diameter increase of red oak, even though November-transplanted trees grew more roots prior to the first bud break following transplant. Among the willow oaks that survived, season of transplant had little effect on new root growth and height growth, but November transplanting resulted in greater trunk expansion. However, when the mortality rate of November-transplanted willow oak is taken into consideration, March may be a better time to transplant willow oak in climates similar to southwest Virginia.
Midwinter Cold Hardiness of Leitneria floridana from Three Provenances
Authors: Sharma Jyotsna , Graves William R.
Published: August 2020

Leitneria floridana Chapman (Florida corkwood) is native to the southeastern and south-central United States. This rare shrub has been cultivated north of its natural habitats. However, the cold hardiness of the species, and potential differences in hardiness among geographical provenances, have not been established. Our objective was to determine midwinter cold hardiness of stem segments from indigenous plants in Texas and Missouri, and from plants that had been cultivated for many years in northern Illinois, but were originally native to Missouri and Arkansas. After exposure to controlled low temperatures, the cortex and phloem were stained with 2,3,5-triphenyltetrazolium chloride (TTC) and compared with discoloration of the same tissues to determine midwinter cold hardiness. The two assays correlated positively, and marked provenance differences in cold hardiness were found. The estimated temperature at which 50% of stems were injured (T50) was ≈ −20C (−4F) in December and−10C (14F) in January for samples from Texas. The estimated T50 for stems from Missouri and Illinois was at or below the lowest temperature tested [−35C (−31F) in December and-60C (−76F) in January]. Stems from cultivated plants in Illinois and from plants indigenous to Missouri were similarly hardy within the range of temperatures used. Autumnal acclimation and vernal deacclimation of L. floridana remain uncharacterized, but midwinter cold hardiness of L. floridana seems sufficient to permit its use north of its natural habitat. Substantial provenance differences in cold hardiness should be considered when selecting plants for landscaping outside the native range of L. floridana.
Short Term Drought Conditioning Influences Adventitious Rooting of Firebush and Fraser's Photinia Stem Cuttings
Authors: Fox Lindsey , Montague Thayne
Published: August 2020

Experiments investigated the influence of drought conditioning stock plants and an auxin-based plant growth regulator (PGR) on adventitious root formation of terminal stem cuttings taken from containerized firebush and Fraser's photinia stock plants. Drought conditioning (DC) treatments were initiated in a glass greenhouse and included: irrigation every day (no DC), irrigation every other day (medium DC), and irrigation every fourth day (high DC). Plants were subjected to DC for 16 consecutive days. Following DC treatments, all plants were irrigated and left overnight. Terminal stem cuttings were taken the following day and an 0.3% auxin talc formulation was used as the PGR. Plant growth regulator/DC treatments included: no DC ± PGR, medium DC ± PGR, and high DC ± PGR. Cuttings were placed under intermittent mist and heating pads maintained media temperature. After 21 and 78 days cuttings were evaluated for rooting percentage, number of roots, and length of the longest root. For firebush, rooting percentage was near 100% for all treatments. Number of roots and length of longest root for firebush cuttings was greatest for cuttings treated with PGR. For Fraser's photinia cuttings, rooting percentage was highest for cuttings treated with high DC + no PGR treatments. Cuttings treated with medium DC or high DC ± PGR treatment produced the greatest number of roots, while mean root length was longest for cuttings treated with medium DC + PGR and high DC + no PGR.
Effect of Transplanting and Paclobutrazol on Root Growth of ‘Green Column’ Black Maple and ‘Summit’ Green Ash
Authors: Watson Gray
Published: August 2020

‘Summit’ green ash (Fraxinus pennsylvanica ‘Summit’) and ‘Green Column’ black maples (Acer nigrum ‘Green Column’) were transplanted and treated with paclobutrazol (PBZ) to study its effect on root growth after transplanting. PBZ increased root extension growth of transplanted ‘Green Column’ maples in the first year after treatment, prior to the onset of above-ground growth regulation. Root growth of transplanted ‘Summit’ ash was not affected by PBZ. Transplanting reduced extension growth of regenerated roots in the first year for ‘Green Column’ maples with no effect on root dry weight. In ‘Summit’ green ash transplanting increased root extension growth in the second year, and root dry weight in both years.
Harvest Season Influences Fertilizer Effects on Seed Production of Lanceleaf Coreopsis
Authors: Norcini Jeffrey G. , Aldrich James H. , Martin Frank G.
Published: August 2020

Seasonal and fertilization effects on seed production were investigated for a north Florida ecotype of lanceleaf coreopsis (Coreopsis lanceolata L.) grown in containers. Since containerized ecotypes of native, herbaceous species are frequently grown using nutrient regimes lower than those for production of typical garden plants, Osmocote 18N–2.6P–10K (18–6–12; 8–9 month formulation) was incorporated into the soilless substrate at one-half the low, low and medium label rates for container-grown plants [1.8, 3.6, and 5.4 kg/m3 (3.0, 6.0, and 9.0 lb/yd3], respectively. Seed were harvested in June, and then again from July–October after plants had been cut back and reflowered. Seed production was greatest for the June harvest based on the number and mass of filled seed per seed head as well as the number of mature seed heads per plant. Number of mature seed heads was directly related to fertilizer rate but this effect varied by harvest season. Seed head production was substantially more responsive to increasing fertilizer rate for the June harvest than for the July–October harvest, which was one of the primary reasons for greater seed production in June. There were also 37% more filled seed per seed head for the June harvest than for the July–October harvest. Seed in June were 67% viable but only 21% of the viable seed germinated. The July–October seed were only 24.7% viable but half of them germinated. Seed harvested during July–October germinated faster than seed harvested in June.
Propagation of Vinca minor by Single-node Cuttings
Authors: Lando Amelia L. , Banko Thomas J.
Published: August 2020

Stems of three Vinca minor L. cultivars (‘Bowles Variety’, ‘Dart's Blue’, and ‘Sterling Silver’) were collected on four dates (January, April, July, and October) and prepared as single-node cuttings, either from the distal 10 cm (4 in) of the stem or from the section of the stem just proximal to that. The cuttings were treated with mixtures of indolebutyric acid (IBA) and naphthaleneacetic acid (NAA) in 50% ethanol at concentrations of 0, 1000 + 500, 2000 + 1000, or 3000 + 1500 ppm (0, 0.1 + 0.05, 0.2 + 0.1, or 0.3 + 0.15%) (IBA + NAA). They were then placed under intermittent mist for rooting. Highest rooting percentages occurred with the 1000 + 500 ppm IBA + NAA treatment. For cuttings taken in October, the proximal cuttings rooted at somewhat higher percentages than the distal cuttings (85 vs. 77%) but at other times, stem position had little effect on rooting. Optimum time of year for rooting varied with cultivar but all cultivars rooted well in October.
Micropropagation of a Cold Hardy Selection of Cercis canadensis L. Through Single-Node Culture
Authors: Dai Wenhao , Jacques Victoria , Herman Dale , Cheng Zong-Ming
Published: August 2020

A cold hardy eastern redbud (Cercis canadensis L., TS 0092) was propagated using single-node micropropagation. In vitro shoot cultures were initiated from rapidly growing shoot tips of a mature tree. The effects of basal media and plant growth regulators on proliferation were investigated. Maximum proliferation rate was obtained from all three tested media, Murashige and Skoog (MS), Woody Plant Medium (WPM), and Driver-Kuniyuki walnut (DKW), supplemented with 0.5 μM thidiazuron (TDZ). Shoots produced on WPM medium appeared stressed showing yellowish and thin leaves compared to those on MS and DKW media. Shoots were in vitro rooted in auxin-free half strength WPM medium after being pulsed for 1 to 16 days in half strength WPM medium with 12.5 to 100 μM indole-3-butyric acid (IBA). In vitro rooting rate was influenced by IBA concentration, pulsing time, and shoot sources (media in which shoots were produced). Shoots produced in DKW medium rooted best after being pulsed in 25 to 100 μM IBA for 8 days although root numbers were similar among treatments. Direct ex vitro rooting was achieved by quick-dipping the microshoots in 10 μM IBA or NAA solutions and inserting them in Jiffy Mix potting medium.
Propagation of Rhamnus alnifolia and Rhamnus lanceolata by Seeds and Cuttings
Authors: Sharma Jyotsna , Graves William R.
Published: August 2020

Rhamnus alnifolia L'Her (Alderleaf Buckthorn) and Rhamnus lanceolata Pursh ssp. lanceolata (Lanceleaf Buckthorn) are native shrubs that are uncommon in the wild. Seed germination of both species and vegetative propagation of R. alnifolia was studied. Germination was low (≤ 13%) among moist-prechilled seeds of R. alnifolia collected in mid-season, but 48% germination was observed among seeds collected late in summer and moist-prechilled for 30 days. Nontreated seeds did not germinate, nor did seeds first scarified with sulfuric acid or hot water followed by moist-prechilling. Germination was ≤ 5% among seeds of R. lanceolata and occurred only after seeds were moist-prechilled for at least 90 days. Seedling survival among both species ranged from 90 to 100% and was not influenced by pregermination treatment. Rooting among softwood cuttings of R. alnifolia was 85% within 35 days after application of 3 g/kg (3000 ppm) or 8 g/kg (8000 ppm) indole-3-butyric acid (IBA) in talc. When IBA was applied in acetone solution at 3 and 8 g/liter (3000 and 8000 ppm), rooting was ≤ 15%. While 75% of the nontreated cuttings rooted, these cuttings had fewer roots than those treated with IBA. Rooting was more extensive in vermiculite compared to a medium of equal volumes of vermiculite and perlite. Talc-based IBA and vermiculite should be used to induce root formation on softwood stem cuttings of R. alnifolia. Both R. lanceolata and R. alnifolia can be propagated from moist-prechilled seeds, but Rhamnus lanceolata is recalcitrant and merits further assessment of drupe phenology, timing of seed collection, and barriers to germination.
Fertilizing Containerized Atlantic White Cedar Seedlings
Authors: Derby Scott A. , Hinesley L. Eric
Published: August 2020

Containerized Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] seedlings were fertilized with five rates (0.0, 2.4, 4.8, 7.2, and 9.6 kg/m3) (0, 4, 8, 12, and 16 lb/yd3) of controlled-release fertilizers (CRF) [Osmocote 15N–4.0P–10.0K (15N–9P2O5–12K2O), 12–14 month southern formulation, with micros; and Polyon 18N–2.6P–10.0K (18N–6P2O5–12K2O), 9-month formulation, with micros]. Height, stem diameter, dry mass, and foliar nutrient concentrations were evaluated after 16 weeks. Growth was affected by fertilizer source and application rate, with no interaction. In general, the response to increasing fertilization was quadratic. Osmocote yielded larger plants than Polyon, probably owing to its higher P content. Osmocote (4.8 to 7.2 kg/m3) (8 to 12 lb/yd3) or Polyon (7.2 kg/m3) (12 lb/yd3) is suggested for container-grown seedlings the first year.
Developmental Stage Influences Plant Response to Benzyladenine
Authors: Oates Jayme M. , Keever Gary J. , Raymond Kessler J.
Published: August 2020

A study was conducted to determine the effects of developmental stage (DS) on plant response to benzyladenine (BA), a synthetic cytokinin that promotes lateral shoot development. Beginning in March, April, or June 2003, three applications of 1750 or 3500 ppm BA were applied at 7-day intervals to ‘Conor’ (Eleanor Taber™) Indian hawthorn (Rhaphiolepis Lindl.) at three stages of increased shoot development (DS 1–3). At 30 and 60 days after last treatment (DALT), new shoot counts were highest on DS 2 plants, and new shoot counts increased with increasing BA rate. Plants treated at DS 1 and DS 2 incurred foliar injury, but not those treated at DS 3. A second experiment with ‘Nigra’ inkberry holly (Ilex glabra L.), ‘Harbour Dwarf’ nandina (Nandina domestica Thunb.), and ‘Conia’ (Olivia™) Indian hawthorn determined how plant DS affected severity of injury following BA application. Extensive foliar injury to ‘Nigra’ inkberry holly occurred when BA was applied to actively growing, immature foliage, but not when applied to mature foliage. Olivia™ Indian hawthorn showed moderate injury following BA treatment of plants with the most immature foliage, but not when plants were treated at more advanced stages of development. ‘Harbour Dwarf’ nandina foliage was unaffected by BA treatment regardless of DS.
Effect of Copper Hydroxide on Slug Feeding
Authors: Thompson Jody M. , Sibley Jeff L. , Foshee Wheeler G. , Keever Gary J. , Appel Arthur G.
Published: August 2020

Kocide® 2000 (53.8% copper hydroxide) and Kocide® 4.5 LF (37.5% copper hydroxide) were examined for their effectiveness at reducing slug feeding using rates found on the Kocide® label. The marsh slug, Deroceras laeve (Müller), was given a choice among two untreated lettuce leaf plugs, one untreated leaf plug and one leaf plug treated with Kocide® 2000 at the rate of 4600 ppm Cu(OH)2 (3.0 tbsp/gal), and one untreated leaf plug and one leaf plug treated with Kocide® 2000 at the rate of 9200 ppm Cu(OH)2 (6.0 tbsp/gal). In a follow-up trial, D. laeve were exposed to Kocide® 4.5 LF at rates of 3100 ppm Cu(OH)2 (1.33 pt/A) and 6200 ppm Cu(OH)2 (2.66 pt/A). A second species, the three-banded slug, Lehmannia valentiana (Férussac), was presented with one untreated lettuce leaf plug and three treated leaf plugs using Kocide® 2000 at the rates of 3100, 6300, and 9400 ppm Cu(OH)2 (2.0, 4.0, and 6.0 tbsp/gal). In each study, D. laeve and L. valentiana showed a preference for the untreated lettuce, indicating that Kocide® 2000 and Kocide® 4.5 LF effectively reduce feeding in these common pest species.
Comparison of Fungicides for the Control of Powdery Mildew on Dogwood
Authors: Hagan A. K. , Olive J. W. , Stephenson J. , Rivas-Davila Maria
Published: August 2020

Efficacy of selected registered fungicides and trifloxystrobin, was evaluated for the control of powdery mildew (Erysiphe pulchra) on container-grown flowering dogwood (Cornus florida). Bare-root trees were transplanted into a pine bark/peat moss substrate and maintained under a 47% shade cloth. All fungicide treatments significantly reduced the incidence of powdery mildew compared with the untreated control. During the trial period, the most consistent control of powdery mildew was given by azoxystrobin [Heritage® 50W] at 0.16 g ai/liter or propiconazole [Banner MAXX®] at 0.07 g ai/liter, respectively. In two of three years, myclobutanil [Eagle® 40W] at 0.24 g ai/liter was equally effective in controlling this disease as the above fungicides. Copper sulfate pentahydrate [Phyton 27®] at 0.74 g ai/liter gave similar control of powdery mildew in three of four years as propiconazole but was not quite as effective in controlling this disease as azoxystrobin. Paraffinic oil at 1% v/v [Sunspray Ultrafine Oil®] was slightly less effective in controlling powdery mildew than azoxystrobin or myclobutanil. However, no more than 6% leaves on the paraffinic oil-treated dogwood were colonized in any year by E. pulchra, compared with 75% colonization for the untreated controls. Although thiophanate methyl [3336™ 4.5F] at 0.84 g ai/liter and triadimefon [Bayleton® WSP] at 0.16 g ai/liter reduced powdery mildew incidence compared with the untreated control, the level of leaf colonization in three of four years was significantly higher than other fungicides. Trifloxystrobin [Compass™ 50W] at the 0.04 g ai/liter rate gave better control of powdery mildew when applied at 1- and 2-week intervals than on a monthly schedule. In contrast, the 0.08 and 0.16 g ai/liter rate of this fungicide were almost equally effective in controlling this disease at 1-, 2-, and 4-week intervals. When applied on the same schedule, myclobutanil (0.24 g ai/liter) gave the same level of powdery mildew control as all three rates of trifloxystrobin. In 1999, moderate to excellent control of powdery mildew with trifloxystrobin, propiconazole, and azoxystrobin resulted in a significant gains in tree dimensions and trunk caliper over those recorded for the untreated flowering dogwood. No symptoms of phytotoxicity were associated with the use of any of the fungicides screened.
Use of Mushroom Compost to Suppress Artillery Fungi
Authors: Davis Donald D. , Kuhns Larry J. , Harpster Tracey L.
Published: August 2020

Mushroom compost (spent mushroom substrate, SMS, mushroom soil) exhibits suppressive characteristics against various fungi, as well as against plant diseases caused by fungi. In addition, mushroom compost has physical and chemical characteristics that make it ideal for blending with landscape mulch to enhance growth of horticultural plants. There is currently an oversupply of used compost in mushroom-growing areas, where it represents a major disposal and regulatory problem. Concurrently, artillery fungi (Sphaerobolus spp.), which commonly live in landscape mulch, have recently become a plague for many homeowners due to the sticky spore masses they expel onto houses and cars. There is increasing interest among homeowners to control artillery fungi without the use of chemical fungicides. Therefore, we have explored the use of aged mushroom compost as a biocontrol agent for artillery fungi. The abundance of mushroom compost, as well as its antagonistic nature to fungi, made it an ideal candidate to blend with landscape mulch to suppress artillery fungi without the use of fungicides. We previously reported that 100% aged mushroom compost suppressed artillery fungi. In the current 3-year field study, we examined the suppressive nature of lower percentages of aged mushroom compost blended with wood landscape mulch. Lower percentages of compost did suppress artillery fungi, but the high variability in the data precluded detailed statistical analyses. Nevertheless, blending mushroom compost with landscape mulch may yield a possible solution for both the compost disposal and the artillery fungi problems.
Feeding, Weight Change, Survival, and Aggregation of Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae) in Seven Varieties of Differentially-Aged Mulch
Authors: Pinzon O.P. , Houseman R.M. , Starbuck C.J.
Published: August 2020

Seven commercially-available mulches were aged outdoors for 0, 6 and 12 months then compared for suitability to the subterranean termite Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae) in non-choice and multi-choice tests under laboratory conditions. Mean differences in mulch consumption, individual termite weight change, and termite worker survival were examined in non-choice tests while mulch consumption and termite aggregation were measured in multi-choice tests. Non-choice tests did not reveal differences in consumption between mulches of the same age. However, mulch consumption and survival increased with mulch age and termite weight loss decreased with mulch age. In multi-choice tests feeding and aggregation preferences shifted with mulch age.
Micropropagation of ‘Amethyst’ Purple Raspberry (Rubus occidentalis L. x R. idaeus L. ‘Amethyst’)
Authors: Dai Wenhao , Magnusson Victoria A. , Hatterman-Valenti Harlene , Carter Jack F.
Published: August 2020

A micropropagation method was developed for a cold hardy purple raspberry cultivar (Rubus occidentalis × R. idaeus ‘Amethyst’). In vitro shoot cultures were initiated from shoot tips of a 30-year old ‘Amethyst’ plant. The effects of basal medium, plant growth regulator, and temperature on shoot proliferation were investigated. Shoots were produced from explants in both Murashige and Skoog (MS) and Driver-Kuniyuki Walnut (DKW) media supplemented with different concentrations of thidiazuron (TDZ) and benzyladenine (BA), solely or combined. One micro molar TDZ gave rise to the maximum proliferation rate. Interactions between BA and medium or TDZ were significant. Shoots produced on media with 1.0 μM TDZ had thick stems and small, dark green leaves whether BA was absent or present. Shoots can be rooted both in vitro and ex vitro with or without IBA at 0 to 1.0 μM. However, combination of rooting and shoot multiplication by adding a low level of TDZ to rooting medium produced multi-cane plants resulting in shortening propagation time, increasing survival rate, and lowering the production cost.
Axillary Shoot Growth, Rooting and Overwinter Survival in Stem Cuttings of Viburnum dentatum ‘Chicago Luster’
Authors: Wilson Philip J. , Struve Daniel K.
Published: August 2020

The effects of stock plant and cutting manipulation on propagation success of Viburnum dentatum ‘Chicago Luster’ were studied. One-node semi-hardwood stem cuttings were harvested from greenhouse-grown stock plants. Cuttings from plants decapitated 21 days before harvest (compared to non-decapitated plants), and one-leaf (compared to two-leaf) cuttings, had relatively high rooting potential and a high initial percentage of axillary shoot flushing. However, subsequent shoot growth, and overwinter survival, were less. A second stock plant decapitation resulted in the flushing and initial growth of all axillary shoots by the time cuttings were stuck. These cuttings all survived the propagation phase and soon resumed shoot growth, even after transplanting, and the plants all survived the following winter. In cuttings with actively growing axillary shoots, shoot extension growth was greatest in cuttings reduced at sticking to one leaf and one shoot in the leafless axil, but the radial distribution of roots was not uniform, being concentrated in the same 180° sector of the stem as the shoot. Incorporating controlled-release fertilizer (CRF) in the rooting substrate during the propagation phase tended to reduce initial survival but promoted rooting and shoot growth among the survivors, even after transplanting and increased overwinter survival.
Harvest Season and Fertilizer Effects on Seed Production of Leavenworth's Coreopsis
Authors: Norcini Jeffrey G. , Aldrich James H. , Martin Frank G.
Published: August 2020

Effects of season and fertilization on seed production were investigated for a central Florida ecotype of Leavenworth's coreopsis (Coreopsis leavenworthii Torr. & A. Gray) grown in containers. Since container-grown ecotypes of native, herbaceous species are frequently grown using nutrient regimes lower than those for production of typical garden plants, Osmocote 18N–2.6P–10K (18–6–12;8–9 month formulation) was incorporated into the soilless substrate at one-half the low, low, and medium label rates for container-grown herbaceous plants [1.8, 3.6, and 5.4 kg/m3 (3.0, 6.0, and 9.0 lb/yd3], respectively. Seed were harvested from mature heads (capitulescences) in late May to mid-July, and then again from late July to late October after plants had been cut back and reflowered. Seed yield and quality were greatest for the May–July harvest. Averaged over fertilizer rate, there were 3-fold more filled seed per mature head for the May–July harvest than during July–October. Mature head production was most responsive to increases in fertilizer rate during May–July. Percent germination of viable seed was nearly 90% or more for both harvests, but there were more viable seed for May–July than for July–October (75 vs. 57%). Seed also ripened much more uniformly during May–July then during July–October. Based on these conditions and results, the best time to harvest seed was from May to early July.
Long-Term Growth of Live Oak Propagated from Rhizomic Shoot Cuttings or Seeds
Authors: Wang Yin-Tung , Niu Genhua
Published: August 2020

Rhizomic shoot cuttings of live oak (Quercus virginiana Mill.) were taken from a single tree about 50 years old in late August 1990, rooted, and planted into 2.6 liter (#1) plastic pots. Concurrently, acorns were collected from the same tree and germinated. Trees from both sources were planted into 13 liter (#5) plastic pots in July 1991 and then to the field in July 1992 either directly in the ground, in 37 or 46 cm (14 and 18 in) diameter polypropylene fabric bags buried in the ground, or in 13 liter pots (#5) placed on the surface. Trunk circumference 10 cm (4 in) above the soil line was measured yearly between 1993 and 1999. Initially, trees from rhizomic shoot cuttings grew slower than seedlings based on trunk circumference, diameter, and cross-sectional area. However, there were no statistical differences after 1996 in trunk circumference, diameter and cross-sectional area between the trees propagated from rhizomic shoot cuttings and seeds. Only in 1993, trees in 37 cm (14 in) bags and plastic pots had greater growth than trees in the ground. About one-third of the seedling trees produced rhizomic shoots in comparison to none of the trees from rhizomic shoot cuttings.
Effect of Potting Media Components on the Infectivity of Metarhizium anisopliae against the Black Vine Weevil (Coleoptera: Curculionidae)
Authors: Bruck Denny J.
Published: August 2020

The black vine weevil (BVW), Otiorhynchus sulcatus (F.) is a serious pest of nursery crops, particularly in the Pacific Northwest. The fungus, Metarhizium anisopliae (F52), has recently been registered by the U.S. Environmental Protection Agency for BVW control. The objective of this study was to determine the persistence of M. anisopliae in five common soilless potting media components (coir, fir bark, hemlock bark, peat moss and perlite), which was measured as pathogenicity against BVW larvae. Fungal granules (½ lb/yd3) were incorporated with each media component at potting and fungal persistence determined for 133 days. Experiments were performed with and without plants to determine if the presence of a plant impacted fungal persistence. Overall, the fungus persisted well in all of the potting media components tested up to 133 days post application. Persistence was somewhat lower in the first experiment, likely due to fluctuating media moisture. In the second experiment, with more stable media moisture levels, the percentage of larval infection did not drop below 88% in any media at 133 days post application. It is likely that M. anisopliae will persist well and provide high levels of BVW larval control in most of the commercial potting media used in containerized nursery production, particularly those comprised primarily of the media components tested in these studies.
Use of Thermal Dissipation Probes to Estimate Water Loss of Containerized Landscape Trees
Authors: Montague Thayne , Kjelgren Roger
Published: August 2020

Granier style thermal dissipation probes (TDPs) have been used to estimate whole plant water use on a variety of tree and vine species. However, studies using TDPs and load cells (gravimetric water loss) to estimate water use of landscape tree species are rare. This research compared gravimetric water loss (estimated with load cells) of four containerized landscape tree species with water loss estimated with TDPs. Over a 66 day period, an experiment compared water loss of three established, 5.0 cm (2 in) caliper poplar (Populus nigra ‘Italica’) trees in 75-liter (20 gal) containers on load cells to TDP estimated water loss. Each tree had a single 30 mm (1.2 inch) TDP inserted into the trunk at four heights above soil level (15, 30, 45, and 60 cm (6, 12, 18, and 24 in, respectively)). Data revealed TDP estimated water loss was less than load cell estimated water loss regardless of TDP height, but TDP estimated water loss at the 30 cm height was closest to actual load cell estimated tree water loss. Over the next three years, similar sized Bradford pear (Pyrus calleryana ‘Bradford’), English oak (Quercus robur x Q. bicolor ‘Asjes’), poplar (Populus deltoides ‘Siouxland’), and sweetgum (Liquidambar styraciflua ‘Rotundiloba’) trees in containers were placed on load cells and one 30 mm TDP was placed into the trunk of each tree 30 cm above soil level. Over an extended time period, tree water loss was estimated using load cells and TDPs. Hourly TDP water loss estimates for each species over a three day period indicate TDP estimated water loss followed similar trends as load cell estimated water loss. However, TDP estimates were generally less than load cell estimates, especially during peak transpiration periods. For each species, mean total daily water loss estimates were less for TDP estimated water loss when compared to load cell estimated water loss. Although TDP estimated water loss has been correlated with actual tree water loss for many species, these data suggest errors may arise when using TDPs to estimate water loss of small, containerized landscape tree species.
Growth Response of Crapemyrtle to Coppicing and Production Light Level
Authors: Brooks K.M. , Keever G.J. , Sibley J.L. , Altland J.E.
Published: August 2020

The effects of production light level on coppicing and coppice timing were evaluated as means of accelerating the development of tree-form crapemyrtles. By the end of the growing season, ‘Fantasy’ and ‘Tuscarora’ coppiced in March and grown under 80% shade were 23 and 18% taller, respectively, than coppiced plants in full sun, but similar in height to plants under 50% shade. Coppiced Dynamite™ under 80% shade and coppiced ‘Carolina Beauty’ under 50% shade were 11 and 26% taller than coppiced plants in full sun, respectively, by the end of the growing season. Height of ‘Fantasy’ and ‘Tuscarora’, but not ‘Natchez’, at the end of the growing season decreased as coppicing was delayed from January to June. ‘Natchez’ coppiced in March were taller than plants coppiced in January or February and 68% taller than plants coppiced in June by the end of the growing season. Cross-sectional stem area of coppiced Dynamite™ and ‘Fantasy’ grown in full sun was greater than that of plants under 50 or 80% shade. Stem area of coppiced ‘Tuscarora’ under 50% shade was greater than that under 80% shade, but similar to that of coppiced plants in full sun. Stem area of coppiced ‘Carolina Beauty’ was greatest when grown in full sun, followed by growth under 50% shade, and least in plants grown under 80% shade. Stem area of ‘Fantasy’, ‘Natchez’, and ‘Tuscarora’ at the end of the growing season decreased linearly as coppicing was delayed from January to June. Visually, coppiced plants had straighter shoots, more uniform shoot diameters, and less branching off the main trunks than non-coppiced plants.
Controlling Height and Seedling Emergence of French Marigold and Celosia Plugs with Plant Growth Regulators
Authors: Magnitskiy Stanislav V. , Pasian Claudio C. , Bennett Mark A. , Metzger James D.
Published: August 2020

Soaking French marigold seeds in growth regulator solutions produced larger reductions in seedling height than foliar sprays. Seeds soaked in 1 to 5 ppm uniconazole solutions for 0.15, 5, or 45 min resulted in plants that were up to 23% shorter than controls at 30 DAS, whereas foliar applications of 10 to 20 ppm uniconazole solutions resulted in plants 18% shorter than controls at 14 DAS. French marigold seedlings from seeds soaked in 60 pm ancymidol for 5 or 45 min were 5 or 6%, respectively, shorter than controls. Foliar spray applications of 25 or 100 ppm ancymidol to French marigold seedlings resulted in plants 8% shorter than controls. Chlormequat solutions applied either as a seed soak (1000–5000 ppm) or foliar spray (500–3000 ppm) did not reduce French marigold seedling height. Emergence of French marigold seedlings from seeds soaked in uniconazole, ancymidol, or chlormequat solutions was not different from that of control seeds. No effect on seedling height or emergence was found when soaking celosia seeds in uniconazole, ancymidol, or chlormequat solutions. Spraying celosia seedlings with uniconazole, ancymidol, or chlormequat solutions did not reduce seedling height.
Ground Pine Chips as a Substrate for Container-grown Woody Nursery Crops
Authors: Wright Robert D. , Browder Jake F. , Jackson Brian E.
Published: August 2020

The objective was to compare pine wood chips (PC) to pine bark (PB) for use as a container substrate for the production of a wide range of woody species. The PC substrate was prepared by grinding coarsely ground [approximately 2.5 cm × 2.4 cm × 0.6 cm (1 in × 1 in × ¼ in)] debarked pine logs (Pinus taeda L.) in a hammer mill to pass a 6.35 mm (0.25 in) screen. Plants of several woody taxa were potted on two different dates (April 4 and May 18, 2005) in each of the two substrates in 3.8 liter (1 gal) containers and grown in a glass house or on outdoor beds in Blacksburg, VA, until late August. Shoot dry weight (SDW) of 13 of 18 species in the April planting was not different between PB and PC, with SDW of four species in this planting being higher when grown in PB and one being higher when grown in PC. Shoot dry weight for 6 of 10 species in the May planting was higher in PB compared to PC. Instances of reduced growth with PC compared to PB were attributed to reduced nutrient availability in PC compared to PB. Results suggest that with adjustments to fertility, PC can be a suitable substrate for container production of woody ornamental plants.
Evaluating a Line Source Irrigation System for Determining Water Requirements of Herbaceous Perennials
Authors: Kjelgren Roger , Cerny-Koenig Teresa
Published: August 2020

We investigated wind effects on the water distribution pattern of a line source irrigation system experimental design that creates a decreasing linear moisture gradient and the growth of twelve perennial wildflower species. Species were randomly assigned to rows perpendicular to a main line of spray irrigation heads, parallel to the decreasing irrigation rates, and irrigated at 110% of evapotranspiration at the heads. At low wind speed (0.44 m/s, 1.4 ft/s), application rates decreased linearly from 50 mm/hr (2 in/hr) for positions closest to the irrigation line to zero at 4 m (12 ft) from the irrigation line. Application rates at positions farthest from the irrigation line were affected by wind speeds as low as 1 m/s (3.3 ft/s). At high wind speeds (3.8 m/s, 12.5 ft/s), application rates at all positions averaged the same across all positions but with extremely high variability. We detected a water stress response in several species known to be drought sensitive. A line source irrigation design offers a potential way to efficiently assess the response of a large number of perennial species to varying irrigation rates by creating a linear moisture gradient, but only when applied under low wind speeds.
Effectiveness of Copper Sulfate Pentahydrate, Mancozeb, and Hydrogen Dioxide in Controlling Anthracnose on Wintercreeper Euonymus
Authors: Boyer Cheryl R. , Cole Janet C. , Conway Kenneth E.
Published: August 2020

Plants of three cultivars of wintercreeper euonymus (Euonymus fortunei (Turcz.) Hand.-Mazz. ‘Emerald Gaiety’, ‘Emerald ‘n Gold’ and ‘Canadale Gold’) were sprayed to runoff weekly with one of three fungicide treatments in 2003 or one of four fungicide treatments in 2004 or water (control) to determine fungicide effectiveness in controlling anthracnose caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Copper sulfate pentahydrate was applied at 0.4 or 0.6 g ai/liter (0.05 or 0.08 oz/gal) or mancozeb was applied at 1.8 g ai/liter (0.2 oz/gal) in 2003 and 2004 while hydrogen dioxide was applied at 1.1 mL ai/liter (0.1 fl oz/gal) in 2004. Plants were rated for disease symptoms monthly. Cultivars differed at every rating date at both sites in both years with ‘Emerald ‘n Gold’ typically having the highest (worst) disease ratings. ‘Canadale Gold’ usually had the lowest (best) disease ratings while ‘Emerald Gaiety’ was intermediate in disease ratings. No differences in disease rating occurred among fungicide treatments in 2003, but plants treated with mancozeb had the lowest disease ratings in 2004. Inhibition of mycelial growth of two isolates of C. gloeosporioides from wintercreeper euonymus by mancozeb or copper sulfate pentahydrate was tested in vitro at 0, 1, 3.2, 10, 31.6, 100, 316, and 1000 ppm ai. Mycelial growth inhibition of both isolates increased curvilinearly as mancozeb or copper sulfate pentahydrate log10 concentration increased. Copper sulfate pentahydrate caused less than 50% inhibition of mycelial growth at all rates tested. The effective concentration to provide 50% inhibition (EC50) of mancozeb on isolate 415 was 645.7 ppm and on isolate 423 was 602.6 ppm.
Management of Poplar Twiggall Fly on Nursery-grown Aspen
Authors: Cranshaw Whitney , Camper Matthew
Published: August 2020

The poplar twiggall fly (PTGF), Hexomyza schineri (Giraud) (Diptera: Agromyzidae), makes smoothly rounded galls on current season twigs of aspen that persist and continue to expand into large swellings years after insect emergence. Early season observations noted that adults make feeding puncture wounds in foliage with their ovipositor that are good indicators of early season activity. Oviposition in twigs results in an observable swelling of tissues within days. However, full development of galls does not occur until approximately two months following oviposition. Adults typically were active for a period of about two to three weeks subsequent to bud break and its primary parasitoid, the eurytomid Eurytoma contractura Bugbee, was trapped at the end of the PTGF flight period. Efforts to prevent adult emergence by painting galls two weeks prior to adult emergence with either sealants (shellac, polyurethane) or insecticides (imidacloprid, abamectin) did not reduce adult emergence. Soil drench treatments of imidacloprid prior to and immediately following bud break significantly reduced PTGF gall production. High rates of thiamethoxam also provided suppression of galling. Foliar applications tested were ineffective in control of gall production by this insect.
Effects of Kaolin Particle Film on the Viburnum Leaf Beetle During Container Production of Viburnum dentatum under Different Levels of Nitrogen Fertilization
Authors: Schultz Hillary S. , Manley Reeser , Halteman William , Susan Erich M. , Schwintzer Christa R. , Stubbs Constance
Published: August 2020

We investigated two pest management strategies for Pyrrhalta viburni (Paykull), a non-native leaf beetle that has invaded New England and is defoliating susceptible wild and cultivated species of Viburnum. SurroundWP (kaolin wettable powder) was tested as a barrier spray during container production of V. dentatum, to determine if it would affect P. viburni leaf damage, oviposition and plant growth. The effect of added N (nitrogen) was also tested. SurroundWP significantly lowered leaf damage and numbers of egg masses in amended plants, without a negative effect on plant growth. Nitrogen use significantly increased leaf damage by adults, numbers of egg masses, and plant growth. These results suggest that commercial growers of susceptible Viburnum species in areas where P. viburni is found could benefit from the use of SurroundWP, and that N amendment should be kept to a minimum.
Residual Toxicity of Imidacloprid to Hawthorn Lace Bug, Corythuca cydoniae, Feeding on Cotoneasters in Landscapes and Containers
Authors: Szczepaniec Adrianna , Raupp Michael J.
Published: August 2020

Cotoneasters are important and valuable landscape plants. They are severely attacked by hawthorn lace bug (Corythuca cydoniae) in landscapes and nurseries. Imidacloprid has a wide range of activity against many kinds of insect pests. We were interested in determining if cotoneasters treated with soil applications of imidacloprid in landscapes and containers remained toxic to hawthorn lace bugs for more than one growing season. Cotoneasters planted in landscapes were less damaged by lace bugs in the year that imidacloprid was applied and in the following year. We suspect that residual toxicity of leaves of cotoneasters particularly to the nymphs of lace bugs as the cause. Cotoneasters grown in containers demonstrated toxicity to lace bugs for almost 800 days after the application of imidacloprid to the soil. These data greatly extend the known period of efficacy for imidacloprid in controlling hawthorn lace bug on cotoneasters. Clearly, lace bugs are controlled for a minimum of two years. By reducing the need for repetitive applications, a single application of imidacloprid can reduce time, labor and material costs associated with managing this important pest of cotoneasters.