bluuebunny/crossref_metadata_2025 huggingface dataset:
Tolerance of Ornamental Grasses to Preemergence Herbicides
Authors: Derr Jeffrey F.
Published: August 2020

Tolerance of ornamental grasses to preemergence herbicides commonly-used in nursery crop production and turfgrass maintenance was evaluated in container studies. Gallery controlled the broadleaf weeds tested but did not control large crabgrass. Surflan at 2.2 kg ai/ha (2.0 lb ai/A) controlled all weeds except rice flatsedge. Pennant at 2.2 kg ai/ha (2.0 lb ai/A) controlled rice flatsedge but not eclipta. Pendulum, Ronstar, Barricade and OH2 also did not control eclipta at the lower use rate. Although growth suppression and stand reduction was observed in certain herbicide/ornamental grass combinations, the species tested generally exhibited good tolerance to the chemicals tested. Ornamental grass tolerance improved by the second herbicide application. After two applications, no rate of Surflan, Pendulum, or Barricade caused a significant reduction in growth of any of the five ornamental grass species tested.
Methods to Evaluate Host Tree Suitability to the Asian Longhorned Beetle, Anoplophora glabripennis
Authors: Ludwig Scott W. , Lazarus Laura , McCullough Deborah G. , Hoover Kelli , Montero Silvia , Sellmer James C.
Published: August 2020

Two procedures were evaluated for assessing tree susceptibility to Anoplophora glabripennis. In the first procedure, adult beetles were caged with a section of sugar maple, northern red oak, white oak, honeylocust, eastern cottonwood, sycamore or tulip poplar wood. Results showed that females laid viable eggs on sugar maple, red oak, white oak and honeylocust. Oviposition did not occur on cottonwood, sycamore, or tulip poplar. Eighty-seven percent of the first instar larvae survived in white oak, followed by sugar maple (82%), honeylocust (50%), and red oak (39%). In the second procedure, first instar larvae were manually inserted into potted sugar maple, green ash, and red oak trees and allowed to feed for 60 or 90 days. Significantly more larvae survived for 90 days within the red oak (67%) compared to green ash (17%). Larvae recovered from red oak weighed significantly more than larvae from sugar maple or green ash. Larval survival was positively related to height of insertion. These results indicate: 1) controlled laboratory and greenhouse-based procedures can be used to assess tree suitability to A. glabripennis and 2) A. glabripennis will oviposit and larvae can develop in northern red oak for up to 90 days, suggesting that this species may be a potential host.
Suitability of Various Species of Viburnum as Hosts for Pyrrhalta viburni, an Introduced Leaf Beetle
Authors: Weston Paul A. , Desurmont Gaylord
Published: August 2020

Viburnum leaf beetle [(Pyrrhalta viburni (Paykull)], a newly introduced pest of viburnums in the United States, feeds selectively on plants in the genus Viburnum. We measured in the laboratory the ability of larvae of viburnum leaf beetle to complete development and propensity of adults to feed on a number of species of Viburnum ranging in susceptibility from completely susceptible to quite resistant as determined by earlier field observations. As expected, larvae completed development on viburnums rated as ‘susceptible,’ but were largely unable to do so on those rated as ‘moderately’ or ‘highly’ resistant. The pattern of host acceptance by adults was less consistent, with some adults feeding considerably on species not found to be susceptible in the field. Several accessions were not fed on at all by adults, indicating the presence of deterrent or toxic factors. Our results suggest that the species previously identified as resistant in the field are unsuitable hosts for viburnum leaf beetle, and will not likely be devastated by the pest even if all susceptible hosts are eliminated from an area.
Evaluation of Experimental Extended-Delivery Granular Preemergent Herbicide Formulations for Direct Application to Nursery Containers
Authors: Fain Glenn B. , Gilliam Charles H. , Wehtje Glenn R. , Grey Timothy L. , Osborne Jason A. , Tilt Ken M.
Published: August 2020

Studies evaluated the efficacy of experimental extended-delivery herbicide formulations for direct application to containers. The purpose for direct application to containers is to reduce non-target loss from the current practice of broadcast applications. A separate laboratory study was also conducted to evaluate the rate response of oryzalin on germination of large crabgrass (Digitaria sanguinalis L.). Results of the laboratory study indicate that crabgrass germination is reduced when seeds are exposed to the preemergence herbicide oryzalin at concentrations of ≥0.025 parts per million. Experimental herbicides were produced by formulating polymeric exchange resins and cellulose complex carriers with oryzalin. Experimental herbicides reduced weed shoot dry weight at 120 DAT and 150 DAT when compared to Rout®, Surflan® and the untreated control.
Propagation of Catnip by Terminal and Single-node Cuttings
Authors: St. Hilaire Rolston
Published: August 2020

Adventitious rooting and subsequent development of rooted cuttings were evaluated for terminal, single-node, and tip cuttings of catnip (Nepeta cataria L.). During an eight-week production period, cuttings were treated with indole-3-butyric acid (IBA) at 0, 1, 3, and 8 g/kg (0, 1000, 3000, and 8,000 ppm), rooted for one to four weeks, and then grown in the greenhouse for four to seven weeks. At harvest, a first experiment showed that terminal cuttings propagated for four weeks accumulated less shoot dry weight (24 g) than cuttings propagated for two (36 g) or three (31 g) weeks. Terminal cuttings treated with 3 g/kg of IBA and propagated for four weeks had the highest root dry weight, which averaged 12.1 g. In the second experiment, length of the longest shoot and primary root and the number of roots and shoots were greater in single-node cuttings propagated for two or three weeks than those propagated for one week. A third experiment revealed that the development of primary roots in single-node and tip cuttings was similar during a 15-day rooting period.
Screening Commercial Peat and Peat-based Products for the Presence of Ericoid Mycorrhizae
Authors: Gorman Nicole R. , Starrett Mark C.
Published: August 2020

Pieris floribunda (Pursh) Benth. & Hook., a known host of ericoid fungi, was used as a model plant to investigate the presence of ericoid mycorrhizal fungi in select peat and peat-based products. After growing in each medium for 75 days, roots of seedlings were examined and average percent colonization was determined for each sample. Results indicate that these fungi are present in the majority of peat and peat-based media tested. Seedlings grown in some of the selected media had a greater percentage of root cells colonized by ericoid mycorrhizae than others in the study.
Molecular Assessment of Remontant (Reblooming) Hydrangea macrophylla Cultivars
Authors: Lindstrom Jon T. , Pelto Matthew C. , Dirr Michael A.
Published: August 2020

Randomly amplified polymorphic DNA (RAPD) markers were used to distinguish five remontant and two cold-hardy Hydrangea macrophylla (Thunb.) Ser. taxa. Eleven primers generated sufficient polymorphisms to separate these seven cultivars into two groups. One group contained ‘Penny Mac’, ‘Dooley’ and ‘Nikko Blue’, while the remaining taxa, ‘David Ramsay’, ‘Endless Summer’, ‘Decatur Blue’ and ‘Oak Hill’ were clustered in the second group. All hydrangea cultivars examined are closely related; the most divergent cultivars exhibited 88% similarity based on RAPD markers.
Effects of Auxin Concentration and Medium Temperature on Four Woody Plant Taxa Propagated by Stem Cuttings using Recirculating Subirrigation in a Growth Chamber
Authors: Owen James S. , Johnson William A. , Maynard Brian K.
Published: August 2020

Four woody plant taxa (‘Sparkleberry’ holly, ‘Mariesii’ viburnum, ‘Shasta’ viburnum, and Red Sunset® maple) were propagated from softwood stem cuttings in a recirculating subirrigation propagation system to evaluate the effect on adventitious root formation of three auxin (Dip-n-Grow®) concentrations [0 (water), 20: 1, or 10: 1] and three medium temperatures [20C (68F), 23C (74F), or 26C (79F)]. All taxa showed a positive rooting response to auxin treatment. Compared to cuttings treated with water, root number of all taxa doubled when treated with the highest auxin concentration (10: 1 Dip-n-Grow® dilution). Length of the longest root of rooted cuttings increased with auxin treatment of two taxa. Medium temperature also affected rooting of all taxa. The intermediate temperature evaluated, 23C (74F), was optimal for all rooting parameters on cuttings of ‘Mariesii’ viburnum, and for root length and percentage rooting on cuttings of ‘Shasta’ viburnum and Red Sunset® maple. A propagation medium temperature of 26C (79F) resulted in the greatest root number on cuttings of ‘Shasta’ viburnum, while 20C (68F) was optimal for root number on cuttings of Red Sunset® maple. Root numbers on cuttings of ‘Mariesii’ viburnum were reduced at 20C (68F) and 26C (79F), which appeared to be sub-and supra-optimal temperatures, respectively, for root initiation. All rooting parameters on cuttings of ‘Sparkleberry’ holly increased with propagation medium temperature. Temperature-auxin interactions were apparent for root number and length on cuttings of ‘Mariesii’ and ‘Shasta’ viburnum. The recirculating subirrigation system was useful for evaluating the basal temperature and auxin dose interactions and was effective for rooting softwood stem cuttings without intermittent mist irrigation.
Multiple Benzyladenine Applications Increase Shoot Formation in Nandina
Authors: Keever Gary J. , Morrison Teresa A.
Published: August 2020

A study conducted from 2000 to 2002 determined the effects of multiple applications of benzyladenine (BA) applied at different concentrations on shoot formation, whole plant size, and phytotoxicity in Nandina domestica Thunb. In 2000, shoot counts increased in ‘Harbour Dwarf’ by up to 107% and 480% as the number of weekly BA applications at 2500 and 5000 ppm, respectively, increased to five. Likewise, the number of shoots per plant increased as BA rate increased. In response to five weekly foliar BA applications in 2001 and 2002, the number of new shoots on ‘Harbour Dwarf’ increased linearly 10-fold over the control as BA rate increased to 5000 ppm in 1250 ppm increments. In 2002, shoot formation increased linearly by up to six additional shoots per plant with increasing BA rate in ‘Harbour Dwarf’ and quadratically by up to two additional shoots per plant in ‘Firepower’ by 90 days after initial treatment (DAT) with five applications of up to 5000 ppm BA. Shoot formation in the tall, upright cultivars ‘Royal Princess’ and ‘Moyer's Red’ also increased linearly with increasing BA rate, by two and <1 shoot per plant, respectively, in 2002 only. Five foliar applications of 2500, 3750, and 5000 ppm BA injured upper, immature foliage, but did not adversely affect plant appearance by 90 DAT. Treatment effects on plant size were minimal.
Response of Lagerstroemia x ‘Tuscarora’ to Multiple Applications of Pistill
Authors: Morrison Teresa A. , Keever Gary J. , Gilliam Charles H.
Published: August 2020

Profuse flowering, followed by heavy fruit set and cessation of vegetative growth, extends the production cycle of many crapemyrtle cultivars, particularly ‘Tuscarora’. A study was conducted in 2002 to determine the effect of multiple applications of 1000 ppm Pistill (ethephon) on flower abortion and subsequent axillary shoot growth in Lagerstroemia indica xfauriei ‘Tuscarora’ when applied to open flowers in July and August before fruit set. In one experiment, Pistill was applied 0, 1, 2, 3, 4, or 5 times during the two flowering periods, and at 7-, 14-, and 21-day intervals (DI) during each period in a second experiment. In the first experiment, two applications made during the July flush led to 48% flower abortion, whereas by the fifth application, made during the August flush, the abortion rate had increased to 58%. Axillary shoot formation occurred predominantly following the July flush, with 34 and 60 new shoots developing on plants receiving one and two applications, respectively. Pistill applications every 7, 14, or 21 days to open flowers during the first floral flush prompted flower abortion of 81, 51, and 18%, respectively, compared to no abortion in untreated trees. The same Pistill treatments applied during the August flush resulted in 96, 96, 54, and 0% abortion, respectively. Trees receiving Pistill at 7 DI, 14 DI, and 21 DI, respectively, formed 96, 108, and two new shoots following the July flower flush and 13, 27, and two new shoots following the August flush.
Technical Information Requested by Hispanic Nursery Employees – Survey Results from Oregon and Ohio
Authors: Mathers H.M.
Published: August 2020

The demographics of the nursery industry in the United States have changed dramatically in the past 10–15 years. Today, the majority of the worker level of nursery staff is Spanish-speaking. Approximately 90% of the Oregon and 60% of the Ohio nursery industry work forces are composed of Hispanic employees. Many of these employees understand little English, and Spanish is their primary language. In Oregon and Ohio 375 and 250 surveys, respectively, were distributed to Spanish-speaking nursery employees. One-hundred-ninety-three surveys were completed in Oregon, as compared to 127 in Ohio. The purpose of these surveys was to determine the backgrounds, experience level and work activities of Hispanic nursery employees, their technical information interests, and what resources were available to these employees. The survey responses came from 3 sources: Interviews at training programs, on-farm visits and mailed surveys in a newsletter format. The three sources were pooled and analyzed. The survey targeted nursery workers filling primarily manual labor positions; however, we found this staff level was predominantly Hispanic. Also, the majority of those surveyed were Hispanic employees who had risen to supervisor or crew leader level, such as propagation area supervisors. Plant identification (95%) and weed control (90%) were the foremost technical topics of interest of Ohio surveyed employees. This was significantly different from the survey results in Oregon where 81% chose insect control, 77% weed control, and 66% disease control as leading topics of interest. In Oregon, plant identification rated only 45%. Ninety-three percent of Ohio and 97% of Oregon newsletter readers wanted to receive future issues of the Spanish language newsletter. This finding was consistent with responses from nursery visits and training programs in the two states where respondents indicated their positive reception to receiving technical information in Spanish.
Effect of Commercial Arbuscular Mycorrhizal Fungi on Growth, Survivability, and Subsequent Landscape Performance of Selected Container Grown Nursery Crops
Authors: Carpio Lucila Amaya , Davies Fred T. , Arnold Michael A.
Published: August 2020

This research evaluated the effects of commercially available arbuscular mycorrhizal fungi (AMF) on growth of selected ornamental plant species grown under a nursery-container production system. Subsequent plant survivability and growth in the landscape was also evaluated for two seasons. Acacia greggii, Chilopsis linearis, Diospyros virginiana, Platanus occidentalis, Ipomoea carnea and Plumbago auriculata were inoculated with commercial AMF: EndoNet®, MycorisePro®, or non-inoculated (NonAMF). Platanus occidentalis had a fourth mycorrhizal treatment, which included BioterraPLUS®. EndoNet® and MycorisePro® enhanced growth of C. linearis, I. carnea and P. auriculata during nursery-container production. Growth enhancement of P. occidentalis was significant with BioterraPLUS®, EndoNet® and MycorisePro® compared to NonAMF. During the container phase, greatest colonization (total arbuscules, vesicles/endospores, and intraradical hyphae) occurred with I. carnea and P. auriculata inoculated with EndoNet® and MycorisePro®. After the 1st growing season following out planting, AMF inoculated P. occidentalis and C. linearis had greater growth and AMF inoculated P. auriculata had higher survival than NonAMF plants. However, by the end of the 2nd growing season there were no differences in survival or growth among AMF treatments. The similarity in plant growth during the 2nd season was due in part to a high and active indigenous AMF population in the landscape site that colonized the NonAMF plants after transplanting.
Models for Predicting the Risk of Naturalization of NonNative Woody Plants in Iowa
Authors: Widrlechner Mark P. , Thompson Janette R. , Iles Jeffery K. , Dixon Philip M.
Published: August 2020

Nursery and landscape professionals have introduced many useful non-native woody plants for managed landscapes, but the potential exists for new introductions to escape from cultivation and become pests. The objective of this study was to develop a comprehensive strategy to assess the risk of naturalization of non-native woody plants in Iowa. We examined life-history traits and native distributions of 100 woody plant species, including 28 species known to naturalize in Iowa and 72 other species not known to naturalize in the state. We tested three approaches to predict naturalization of woody plants in Iowa: (1) direct application of a previously developed decision tree designed to predict naturalization on a continental scale within North America; (2) application of the continental model modified to include traits important on a regional scale, and (3) development of a new regional model that included a geographic-risk component along with life-history traits. Our modifications to the continental model and the new regional model all were more powerful than the unmodified, continental model, as measured by their ability to classify species (classification rate) based on risk of naturalization, without reducing accuracy, as measured by the frequency of misclassification (error rate). Classification rates ranged from 65% for the unmodified continental model to 90% for the modified continental model. Error rates varied from 6% for the new regional model to 20% for the unmodified continental model, including horticulturally limiting error rates of 4 to 17%, respectively.
Effect of Chilling Duration on Growth of Hosta plantaginea and 11 Related Cultivars
Authors: Warr Jennifer C. , Keever Gary J. , Raymond Kessler J. , Findley Douglas A. , Amling Jason W.
Published: August 2020

Hosta plantaginea and 11 selections with H. plantaginea parentage were chilled at 4C (39F) for 0, 1, 2, 3, or 4 weeks to determine the effect of chilling duration on subsequent plant growth. At 6 and 12 weeks after chilling treatment (WAT), response to chilling duration was selection dependent with three trends evident. At 6 WAT, eight of the 12 selections showed a decrease in new leaf formation with one or two weeks of chilling, but an increase in new leaf formation with additional chilling. In three of the 12 selections, new leaf formation increased linearly with increased chilling. New leaf formation of H. plantaginea ‘Grandiflora’ was not affected by chilling duration at 6 or 12 WAT. At 12 WAT, growth response of four of the 12 selections changed quadratically with increased chilling, similar to the response at 6 WAT, while leaf formation in seven of the 12 selections increased linearly with increasing chilling duration. At 18 WAT, leaf counts increased linearly in all H. plantaginea selections with increasing chilling duration, demonstrating increased vigor. All selections showed increases in new leaf formation over the 18-week period following chilling, demonstrating that chilling, though beneficial, was not required, and in the short-term, the response to chilling was selection dependent.
Propagation of Ulmus parvifolia ‘Emerald Prairie’ by Stem Cuttings
Authors: Griffin Jason J. , Schroeder Kenneth R.
Published: August 2020

Stem cuttings of Ulmus parvifolia Jacq. ‘Emerald Prairie’ (‘Emerald Prairie’ lacebark elm), consisting of 7.5 to 10 cm (3 to 4 in) terminal shoot portions, were collected four times throughout the year from mature stock plants and treated with the potassium (K) salt of indole-3-butyric acid (K-IBA) ranging from 0 to 20,000 ppm (2.0%). Rooting percentages were affected greatly by K-IBA treatment and stock plant growth stage. Little to no rooting was observed without K-IBA application, whereas overall rooting for treated softwood, early semi-hardwood, late semi-hardwood, and hardwood, cuttings was 92, 86, 87, and 8%, respectively. Mean root number varied by growth stage and K-IBA concentration. Higher concentrations of K-IBA increased the number of roots on rooted cuttings except for hardwood cuttings. In general, rooting percentage and mean root number were highest at the softwood stage with 15,000 or 20,000 ppm (1.5 or 2.0%) K-IBA, resulting in 97% rooting and 15 or 22 roots per rooted cutting, respectively. However, leaf abscission was high on softwood cuttings. Semi-hardwood cuttings achieved similar rooting percentages and may exhibit better survival and growth due to greater leaf retention.
White Grub (Coleoptera: Scarabaeidae) Population Density in Relation to Root Damage to Fraser Fir Seedlings in Transplant Beds
Authors: Williamson R. Chris
Published: August 2020

A field experiment was conducted in 2002 to evaluate the effect of five grub densities of second instar Phyllophaga anxia (LeCont) Glasgow larvae on feeding damage to roots of young seedlings of Fraser fir, Abies fraseri (Pursh) Poir., Christmas trees in a transplant bed. Larval densities were equivalent to approximately 0, 31, 62, 93, and 124 larvae per m2 (≈ 0, 3, 6, 9, and 12 larvae per ft2). Larval survival and variations in larval and seedling weight were also evaluated. Regardless of the larval density, when P. anxia grubs were present, all Fraser fir seedlings experienced significant root damage as well as subsequent plant injury (i.e., decline or mortality). Larval density as low as one grub per 0.11 m2 (≈ 3 larvae per ft2) caused heavy to severe root damage to young, two-year-old, P2-0 Fraser fir seedlings. An inverse relationship was observed between plant weight and root damage.
Effect of Pruning, Defoliation, and Promalin on New Shoot Development of Boxwood
Authors: Musselwhite Sheri , Harris Roger , Latimer Joyce , Wright Robert
Published: August 2020

The objective of this study was to determine if summer dormancy of the boxwood species Buxus sempervirens L. ‘Suffruticosa’, B. sempervirens ‘Vardar Valley’, and B. sinica var. insularis Nakai ‘Justin Brouwers’ could be overcome by pruning, defoliation or growth regulator applications. Promalin (benzyladenine (BA) + GA 4+7) alone and in combination with pruning increased new shoot growth; however, results were not consistent across experiments. Pruning alone (shearing or tip removal) was also inconsistent in inducing new shoot growth. Defoliation (removal of leaves from new spring growth) dramatically increased new shoot development, especially when applied ten weeks after spring budbreak instead of closer to budbreak. This response was tempored by Promalin application.
Regeneration of Mugwort (Artemisia vulgaris) from Rhizome Sections in Sand, Pine Bark, and Soil Substrates
Authors: Klingeman William E. , Robinson Darren K. , McDaniel Gary L.
Published: August 2020

Regenerative potential of mugwort (Artemisia vulgaris L.) rhizome sections has not been quantified when rhizomes are transplanted into substrates encountered in landscapes and nursery fields, container nurseries, or propagation beds. Mugwort regeneration in pine bark, sand, and soil substrates was analyzed by rhizome color, length, and the presence or absence of a leaf scale. Color of rhizomes, which darken with time, did not account for differences in growth among treatments. Contrary to previous research, 85, 78, and 69% of 2 cm-long rhizome sections produced both roots and shoots when grown in pine bark, sand, and soil substrates, respectively, during 45-day trials. Slightly less than 31% of rhizome fragments 0.5 cm long without a leaf scale produced both roots and shoots in soil. Though fewer rhizomes survived in soil, root and shoot fresh weights were greater than in pine bark and sand. When rhizome sections included a leaf scale, survival, fresh weights of roots and shoots, shoot height, leaf number and root lengths were greater, regardless of substrate type. Root initials emerged both adjacent to leaf scales and in the internode between leaf scales. Shoot emergence preceded root emergence from rhizome sections.
Evaluation of 19 American Elm Clones for Tolerance to Dutch Elm Disease
Authors: Townsend A. M. , Bentz S. E. , Douglass L. W.
Published: August 2020

Rooted stem cuttings of 19 American elm (Ulmus americana L.) cultivars and selections, and rooted cuttings of two non-American elm selections, U. carpinifolia Gleditsch 51 and 970 (U. glabra Huds. x (U. wallichiana Planch. x U. carpinifolia)), along with a group of American elm seedlings, were planted in a randomized block design. When the trees were nine years old, they were inoculated with a mixed spore suspension of Ophiostoma ulmi (Buisman) C. Nannf. and Ophiostoma novo-ulmi Brasier, the causal fungi for Dutch elm disease (DED). Analyses of variance showed highly significant variation among clones in foliar symptoms 4 weeks after inoculation and in crown dieback one and two years after inoculation. After two years, 13 of the American clones showed significantly less dieback than the American elm seedlings, and 18 American clones showed significantly less injury than a randomly chosen, unselected American elm clone, 57845. The American clones with the most DED-tolerance were cultivars ‘Valley Forge,’ ‘Princeton,’ ‘Delaware,’ and ‘New Harmony,’ and selections N3487, R18-2, 290, 190, and GDH. The non-American selections 51 and 970 also exhibited high levels of disease tolerance. Most susceptible were American clones 57845, ‘Augustine,’ Crandall, W590, and the American elm seedlings. The most disease-tolerant American elm selections identified in this study are being evaluated further for possible naming and release to the nursery industry.
Response of ‘Moonbeam’ Coreopsis and ‘Goldsturm’ Rudbeckia to B-Nine and Cycocel
Authors: Amling J.W. , Keever G.J. , Kessler J.R. , Eakes D.J.
Published: August 2020

Coreopsis verticillata ‘Moonbeam’ and Rudbeckia fulgida ‘Goldsturm’ were sprayed with tank mixes of B-Nine and Cycocel in all combinations of 0, 2500, 5000 or 7500 ppm B-Nine and 0, 1000, 1500 or 2000 ppm Cycocel. B-Nine was more effective in controlling height of both cultivars than Cycocel or B-Nine/Cycocel tank mixes. B-Nine alone suppressed height of coreopsis 26-52% (over all concentrations and all data collection dates), in contrast to a 17–41% height suppression when B-Nine was combined with Cycocel. Cycocel alone suppressed height of coreopsis 6–16% over all concentrations and data collection dates. B-Nine suppressed height of rudbeckia 20–40% over all data collection dates, while Cycocel suppressed height of rudbeckia only in the last two weeks of data collection (10 and 12% at weeks 8 and 9, respectively). Tank mixes applied to rudbeckia were not as effective as B-Nine alone for height suppression. Flowering of coreopsis was delayed 6 days by B-Nine and 12–14 days by tank mixes of B-Nine and Cycocel; Cycocel accelerated flowering up to 5 days when used alone. Flowering of rudbeckia was delayed up to 9 days with increasing B-Nine concentrations but was unaffected by Cycocel alone or tank mixes of B-Nine/Cycocel. No phytotoxicity was observed at the concentrations used.
Influence of Selected Surface Disinfestants, Fungicides, and Temperature on Seed Germination and Initial Growth of Southern Seaoats (Uniola paniculata)
Authors: Burgess Tyler L. , Blazich Frank A. , Nash David L. , Randall-Schadel Betsy
Published: August 2020

Seeds of southern seaoats (Uniola paniculata L.) were removed from storage at 4C (39F) and treated with the following selected surface disinfestants, fungicides, or combinations of these chemicals: nontreated (control), 1.3% sodium hypochlorite [NaOCl (chlorine bleach)], 2.6% sodium hypochlorite, RTU® (12.6% thiram + 0.34% thiabendazole), RTU®-PCNB (24% pentachloronitrobenzene), 1.3% sodium hypochlorite and RTU®, 2.6% sodium hypochlorite and RTU®, 1.3% sodium hypochlorite and RTU®-PCNB, or 2.6% sodium hypochlorite and RTU®-PCNB. Following treatment, seeds were germinated at an 8/16 hr thermoperiod of 35/20C (95/68F). The seed treatments and germination thermoperiod utilized were based on three preliminary trials that investigated the influence of selected surface disinfestants, fungicides, and temperature on seed germination of the species. Germination was recorded every 3 days for 30 days. Seed treatment was highly significant (P = 0.0001) for both total percentage germination and total percentage of decayed seeds. Germination of nontreated seeds was 45%, and four treatments resulted in germination > 80% [RTU®-PCNB (81%), 2.6% sodium hypochlorite and RTU® (83%), 1.3% sodium hypochlorite and RTU® (87%), and 1.3% sodium hypochlorite and RTU®-PCNB (89%)]. A subsequent experiment investigated the effects of the aforementioned treatments with the exception of 1.3% sodium hypochlorite and RTU®, both used alone, on initial seedling growth of the species. Following treatment, seeds were sown in containers filled with a peat-based medium and the containers placed in a growth chamber maintained at an 8/16 hr thermoperiod of 35/20C (95/68F) with long day conditions. Emergence data were recorded every 3 days for 45 days. After 45 days, the study was terminated and additional data recorded to include plant height (height of main stem), leaf number, length and width of the two longest leaves, and top and root dry weights. Surface disinfestant, fungicide, and combination treatments were highly significant (P = 0.0004). Percentage emergence of nontreated seeds was 35% and five of the seven treatments resulted in emergence ≥ 75% [2.6% sodium hypochlorite (75%), 1.3% sodium hypochlorite and RTU® (75%), 1.3% sodium hypochlorite and RTU®-PCNB (76%), 2.6% sodium hypochlorite and RTU®-PCNB (81%), and 2.6% sodium hypochlorite and RTU® (83%)] with negligible effects on seedling growth. There were significant treatment differences regarding some of the variables used to evaluate seedling growth. In most cases these differences were due to seedlings from nontreated seeds having lower values for each measured variable than values for the same variables from treated seeds. Results of both experiments demonstrate the potential value of chemical seed treatment during production of seedling transplants of U. paniculata.
A New System to Monitor Water and Nutrient Use in Pot-inpot Nursery Production Systems
Authors: Zhu H. , Krause C.R. , Zondag R.H. , Brazee R.D. , Derksen R.C. , Reding M.E. , Fausey N.R.
Published: August 2020

Techniques are needed to monitor nursery production practices for proper use of water resources and nutrient management. An experimental system to examine water quality, irrigation efficiency and drainage from pot-in-pot nursery container production was established in a commercial nursery. The system mainly consisted of 50 pot-in-pot containers with 50 trees irrigated with micro spray stakes, drainage water measurement devices, container-substrate moisture probes, thermocouples, a weather station, and data loggers. Tests indicated the system was capable to measure irrigation and rainfall inputs, drainage water loss, container substrate moisture content and temperature, leachate of nitrogen, phosphate and potassium in drainage water, and tree growth in pot-in-pot nursery production. The system provided a method to not only monitor the loss of water and nutrients but also continuously monitor the substrate temperature and moisture content during four seasons of a year to evaluate potentials of winter injury or summer heat damage to roots for pot-in-pot nursery production.
Initial Plant Size and Landscape Exposure Affect Establishment of Transplanted Kalmia latifolia ‘Olympic Wedding’
Authors: Wright Amy N. , Warren Stuart L. , Blazich Frank A. , Harris J.Roger , Wright Robert D.
Published: August 2020

Effects of plant size and landscape exposure on survival and subsequent growth of transplanted, container-grown mountain laurel (Kalmia latifolia L. ‘Olympic Wedding’) were studied at two locations. Plants of ‘Olympic Wedding’ mountain laurel grown in 1, 7.5, or 19 liter (1 qt, 2 gal, or 5 gal) containers for 1,2, or 3 years, respectively, were transplanted in Raleigh, NC, and Blacksburg, VA, in tilled beds amended with pine bark along four exposures (north, south, east, and west). In Raleigh, survival increased with increasing container size with plants grown initially in 19 liter containers having the highest rate of survival whereas, survival was greatest on the east and north exposures and lowest on the west exposure. There was no difference in survival between container sizes or exposures for plants grown in Blacksburg. After three growing seasons in the landscape, visual ratings in Raleigh were higher for plants grown initially in 7.5 liter (2 gal) containers than for plants grown in 1 (1 qt) or 19 liter (15 gal) containers. Visual ratings were higher on north and east exposures than on south and west exposures regardless of container size. In Blacksburg, percent leaf scorch was lower for 1 and 7.5 liter (1 qt and 2 gal) plants, than for 19 liter (5 gal), and was highest on west exposures. Growth index (GI) increased 118% from 1999 to 2001 in Raleigh and 225% from 1999 to 2002 in Blacksburg for 1 liter (1 qt) plants and 51% in Raleigh and 78% in Blacksburg for 7.5 liter (2 gal) plants over the course of the experiment. There was an initial increase in GI for 19 liter (5 gal) plants in both locations, but in subsequent years GI decreased due to stem dieback. In Raleigh, GI of 7.5 liter (2 gal) and 19.5 liter (50 gal) plants grown on the east exposure was greater than plants grown on the south exposure with no difference due to exposure at Blacksburg. Results suggest that in climates similar to Raleigh, initial container size and exposure affect survival of transplanted mountain laurel, but in cooler climates like Blacksburg, initial container size and exposure may not be critical factors except in windy exposures.
Cotton Gin Compost as a Substrate Component in Container Production of Nursery Crops
Authors: Jackson Brian E. , Wright Amy N. , Cole David M. , Sibley Jeff L.
Published: August 2020

Shoot and root growth of plants grown in substrate blends containing cotton gin compost (CGC) were compared to plants grown in a traditional pine bark (PB) blend. In 2002 ‘Winter Gem’ boxwood, ‘Firepower’ dwarf nandina, and ‘Midnight Flare’ azalea were potted in four substrate blends containing by volume 6:1 PB:sand (S), 4.5:1.5:1 PB:CGC:S, 1:1 PB:CGC, or 1.5:4.5:1 PB:CGC:S. Plants were grown for nine months on a container pad in Auburn, AL. In 2003–2004 this study was repeated with ‘Renee Mitchell’ azalea as a replacement for ‘Midnight Flare’ azalea. Periodic growth measurements and a final visual root ball evaluation were conducted in each experiment. Substrates were analyzed to determine physical properties (air space, water holding capacity, total porosity, and bulk density) and chemical properties (pH and electrical conductivity). In both experiments, growth indices of all cultivars in substrates containing CGC were similar to or greater than those of the PB:S control blend. Visual quality of root systems was similar for all plants across all substrates.
Effects of Long-Term Recycled Wastewater Irrigation on Visual Quality and Ion Concentrations of Ponderosa Pine
Authors: Qian Y.L. , Fu J.M. , Klett J. , Newman S.E.
Published: August 2020

Recycled wastewater (RWW) has become a common water source for irrigating golf courses and urban landscapes. Ponderosa pine (Pinus ponderosa) is commonly used in urban landscape settings in the Rocky Mountain West. To evaluate the effects of RWW irrigation on quality and needle ion accumulations of ponderosa pine, eight landscape facilities near metropolitan Denver, CO, were selected for the experiment. Among these sites, four had been irrigated exclusively with domestic RWW [electrical conductivity (EC) = 0.84 dS/m] for 5, 6, 15, and 20 years, respectively. The other four with similar turf species, age ranges, and soil textures had been irrigated with surface water (EC = 0.23 dS/m). Ponderosa pines grown on sites irrigated with RWW exhibited 10 times higher needle burn symptoms than those grown on sites irrigated with surface water (33% vs. 3%). Tissue analysis indicated that ponderosa pine needles collected from sites receiving RWW exhibited 11 times greater Na+ concentration, 2 times greater Cl−, and 50% greater B concentrations than samples collected from the control sites. Stepwise regression analysis revealed that the level of needle burn was largely influenced by leaf tissue Na+ concentration. Tissue Ca level and K/Na ratio were negatively associated with needle burn symptoms, suggesting that calcium amendment and K addition may help mitigate the needle burn syndrome in ponderosa pine caused by high Na+ in the tissue.
Seedling Growth, Leaf Injury and Ion Uptake Response of Cold-Resistant Palm Species to Salinity
Authors: Khurram S. , Miyamoto S.
Published: August 2020

Palms are becoming popular landscape plants in the upper desert region of the Southwest where water used for irrigation has elevated salinity. An experiment was conducted in a greenhouse to evaluate leaf damage and growth response of nine cold-resistant palm species to salinity. One-year-old potted seedlings were transplanted to 10-liter containers filled with loamy sand and irrigated with saline solutions containing 800, 2000, 5000, and 7500 mg/liter of predominantly NaCl salts. The corresponding electrical conductivity was 1.2, 4.4, 9.4, and 13.7 dS/m, respectively. Seedlings were irrigated at a leaching fraction of 30 to 35% for six months, and leaf growth, leaf injury, and leaf mineral contents measured. Under this irrigation regime, salinity of irrigation solutions approximately equals salinity of the soil saturation extract. Leaf growth and leaf injury were highly species-dependent. A significant growth reduction and leaf injury of Sabal palmetto, Butia capitata, and Trachycarpus fortunei appeared when irrigated with the 4.4 dS/m solution, those of Trithrinax brasiliensis, Brahea armata, and Sabal minor when grown with the 9.4 dS/m solution, and Washingtonia filifera, Washingtonia robusta and Phoenix canariensis, using the 13.7 dS/m solution. Injured leaves of poorly-tolerant species contained unusually large amounts of Na (10 to 70 g/kg) when irrigated with the 9.4 dS/m solution. W. filifera, W. robusta, and P. canariensis seem to be ideal species for saline areas.
Root Pruning and Transplant Success for Cathedral Oak® Live Oaks
Authors: Gilman Edward F. , Anderson Patti J.
Published: August 2020

Trees that were root pruned regularly throughout the production period grew at a slower rate than trees that were not root pruned, but root pruning only in the last year of production did not affect trunk and canopy growth. Trees with root-pruning fabric installed under liners at planting grew at the same rate as trees without fabric during 39 months of field production. Hand spade root pruning throughout the production period increased the number of small diameter (< 3mm) roots and decreased the number of large diameter roots in the root ball compared to trees that were not root pruned. Root pruning only in the last year of production reduced the number of large diameter roots but did not increase the number of small diameter roots. Fabric had no impact on the root system. Root pruning with a hand spade throughout production or only in the last year of production reduced water stress significantly in trees following digging compared to trees not root pruned during production. Root-pruning fabric installed under liners at planting reduced stress following digging 39 months later, but only on two of the days when water stress was measured.
Accumulation of a Protein Associated with Plant Defense in Powdery Mildew Resistant Dogwood (Cornus florida)
Authors: Mmbaga M.T. , Avila F.J. , Howard E.F. , Myles E.L.
Published: August 2020

This study was conducted to better understand the nature of powdery mildew resistance in flowering dogwood (Cornus florida L.) and in particular to determine if inducible plant defense proteins are associated with powdery mildew resistance. Results from this study showed an accumulation of a new protein in resistant plants, but not in susceptible plants that were challenged with powdery mildew pathogen (Erysiphe (Sect. Microsphaera) pulchra). The protein accumulated in a high level in the resistant selections at 48 hr after inoculation with the pathogen and that was consistent with the production of pathogenesis related (PR) proteins. The protein was characterized as having an isoelectric point of 7.5 ± 0.5 and molecular weight of 18 ± 2 KD. Partial sequence analysis of this protein revealed homology with PR-10 protein associated with drought resistance in potato and was analogous to other proteins related to resistance in other crops. Repeated analysis showed similar results and suggested that a biochemical mode of resistance involving plant defense proteins may be associated with powdery mildew resistance in flowering dogwood.
Postemergence Oxalis Control with Diuron: Minimizing Crop Injury with Timely Irrigation
Authors: Richardson Ben M. , Gilliam Charles H. , Wehtje Glenn R. , Fain Glenn B.
Published: August 2020

Experiments were conducted to evaluate tolerance of container nursery crop tolerance and yellow woodsorrel (Oxalis stricta) control with postemergence applied diuron as influenced by timely overhead irrigation. Intent was to identify an interval between application and irrigation that may reduce crop injury without compromising oxalis control. Diuron was applied at a common rate of 1.0 lb ai/A to oxalis and two nursery crops (Camellia sasanqua ‘Alabama Beauty’ camellia, and Rhododendron indicum ‘G.G. Gerbing’, azalea). Treatments consisted of irrigation at 1, 2, 4, 8, 12, 24, or 48 hr after application. Oxalis control was equivalent whether treated plants were irrigated within either 1 hr or 48 hr after application. Camellia exhibited no visible injury regardless of treatment. Azaleas exhibited diuron-induced injury, however injury was reduced if plants were irrigated within 1 hr of diuron application. 14C-diuron was used to determine the absorption rate of foliar-applied diuron into oxalis, camellia and azalea. Absorption by oxalis was relatively rapid, and reached a maximum (∼68% of applied) within 8 hr after application. Camellia and azalea absorbed a smaller percentage of the amount applied, and absorption was more protracted over time compared to oxalis. Azalea absorbed slightly more than camellia. Diuron has potential for use as an over-the-top application for postemergence oxalis control and timely irrigation has the potential to reduce injury to sensitive crops.
Seedling Populations Produced by Colored-leaf Genotypes of Japanese Barberry (Berberis thunbergii DC.) Contain Seedlings with Green Leaf Phenotype
Authors: Lehrer Jonathan M. , Brand Mark H. , Lubell Jessica D.
Published: August 2020

The leaf color of seedling populations derived from ornamental genotypes of Japanese barberry (Berberis thunbergii DC.) was evaluated to determine whether nursery selections of this important landscape plant could be expected to produce green-leaf progeny or seedlings with leaf color resembling the purple-leaf or yellow-leaf parent. This is a compelling inquiry since nearly all B. thunbergii plants found within invasive populations possess green foliage and the potential contribution of seedlings by ornamental purple-and yellow-leaf genotypes is unknown. Seed lots collected from cultivated barberry genotypes located in landscape settings were processed and raised in a greenhouse to observe leaf color phenotype. It was found that all genotypes studied produced at least some green seedlings. The percentage of green progeny produced varied widely by genotype. Green-leaf cultivars yielded close to 100% green seedlings and all purple-and yellow-leaf forms produced at least 20% green offspring. Among purple-leaf genotype accessions located adjacent to potential purple-leaf pollen donors, var. atropurpurea produced significantly fewer green seedlings (18.5%) than ‘Crimson Pygmy’ (71%) and ‘Rose Glow’ (45%). ‘Rose Glow’ individuals growing adjacent to other purple Japanese barberry forms produced significantly fewer green seedlings (45%) than ‘Rose Glow’ accessions that were isolated from additional purple Japanese barberry (88%). This study demonstrates that some invasive green-leaf B. thunbergii could be derived from popular garden forms since purple- and yellow-leaf genotypes readily produce green-leaf offspring which resemble feral barberry. These findings do not, however, provide any definitive link between cultivated and naturalized Japanese barberry.
Control of Northern Willowherb in Nursery Containers
Authors: Altland James , Cramer Eryn
Published: August 2020

Four experiments were conducted to determine the effectiveness of granular and sprayed preemergence herbicides for controlling northern willowherb (Epilobium ciliatum Rafin) in container crops. Eleven granular herbicides representing various combination of pendimethalin, prodiamine, oryzalin, oxyfluorfen, oxadiazon, napropamide, isoxaben, trifluralin, and flumioxazin were evaluated, as well as sprayed Surflan AS (oryzalin), Devrinol 50-DF (napropamide), Barricade 4FL (prodiamine), and Gallery 75DF (isoxaben). Herbicides were applied to recently filled containers and irrigated with overhead sprinklers. Weed numbers were counted in each pot and weed shoot dry weight was measured at the conclusion of each study. Ronstar G (oxadiazon) at 4.48 kg ai/ha (4 lb ai/A) consistently provided the most effective control among all herbicides. Other granular herbicides containing oxadiazon were also effective. Surflan and Devrinol did not consistently reduce weed numbers as effectively as Ronstar G, however they did reduce subsequent growth of northern willowherb seedlings that were able to successfully establish. Gallery did not provide any control alone nor did it improve control when tank mixed with other products.
Determining Water Use and Crop Coefficients of Five Woody Landscape Plants
Authors: Niu G. , Rodriguez D.S. , Cabrera R. , McKenney C. , Mackay W.
Published: August 2020

The water use and crop coefficient of five woody landscape species were determined by growing the shrubs both in 56-liter (15 gal) drainage lysimeters and in above-ground 10-liter containers (#3). Water use per plant, crop coefficient and overall growth parameters differed by species and culture system. Of the five species tested, Buddleia davidii ‘Burgundy’ and Nerium oleander ‘Hardy Pink’ had higher water use per plant in the lysimeters than in the containers. Water use per plant for Abelia grandiflora ‘Edward Goucher’, Euonymus japonica and Ilex vomitoria ‘Pride of Houston’ was the same for the two culture systems. Crop coefficient and growth index of A. grandiflora, E. japonica, and I. vomitoria was similar between the two systems. The growth index of B. davidii and N. oleander was much higher in the lysimeters than in the containers. Abelia grandiflora and E. japonica had more growth in the containers than in the lysimeters while I. vomitoria had slightly larger leaf area in the lysimeters than in the containers. The culture system did not affect the water use per unit leaf area of all species. Therefore, our results indicated that by quantifying the leaf area, the plant water use in the two culture systems is exchangeable.