J. Environ. Hort. 27(1):1–6. March 2009 Evaluation of Clay Aggregates in Perennial Offshoot Production1 Jeremy M. Pickens2, Glenn B. Fain3, Jeff L. Sibley4, Charles H. Gilliam4, and John W. Olive5 Department of Horticulture, 101 Funchess Hall Auburn University, AL 36849 Abstract In an effort to compare yield and time required to remove substrate from roots of liners, Ophiopogon japonicus and Ophiopogon japonicus ‘Nana’ (lilyturf) bare root bibs were potted into 100% aged pine bark, 8:2 (v:v) pine bark:peat moss, 100% perlite, 100% fine grade Profile™ porous ceramic (Profile™ products LLC, Buffalo Grove, IL), or 100% course grade Profile™ porous ceramic. In a second study Ophiopogon japonicus was potted into 100% aged pine bark, 100% 3/16-inch HydRocks® (Big River Industries Alpharetta, GA), fine grade 100% Profile™, 100% perlite, 100% sand, 8:2 (v:v) pine bark:peat moss, and 3:1 (v:v) 3/16 HydRocks®:sand. In the second study, fine grade Profile™ produced the highest number of total bibs per container and bib production was similar to 8:2 pine bark:peat moss. HydRocks® was similar to pine bark in total bibs per container but was more efficiently removed from roots. Removal of the HydRocks® substrate from plant roots required 50% less time than removal of pine bark:peat moss substrate and 51% less time than removal of pine bark substrate. HydRocks® took 23% less time to remove from roots than fine grade Profile™. Results indicate that clay materials such as HydRocks® and Profile™, when compared to conventional substrates can provide suitable yields while also decreasing labor cost by decreasing time to bare-root. Index words: Profile™, HydRocks®, bibs, lightweight aggregate. Species used in this study: lilyturf (Ophiopogon japonicus (Thumb.) Ker-Gawl.; Ophiopogon japonicus ‘Nana’. J. Environ. Hort. 27(1):7–11. March 2009 Pruning Roots Affects Tree Quality in Container- Grown Oaks1 Edward F. Gilman2, C. Harchick and C. Wiese Environmental Horticulture Department University of Florida, Gainesville, FL Abstract Height and trunk growth of Quercus virginiana ‘SDLN’ Cathedral Oak® tops was not affected by root pruning that occurred each time trees were potted into a larger container, beginning when rooted cuttings were planted into #3 containers. All trees produced in air root-pruning Accelerator® containers without mechanical root pruning produced enough circling roots to make them culls according to Florida and California standards for nursery stock. Removing root defects by pruning roots when trees are potted to the next larger size reduced culls from 100% to 40% of the crop and is recommended for quality tree production. Root pruning when trees were potted from one container size to the next size had no influence on the number of primary structural roots that grew directly from the trunk base. Root pruning had no impact on the number of roots that were deflected down. Waiting to root prune until #3 containers were potted into #15 containers did not increase the number of straight roots compared to non-pruned controls. Slicing the root ball edges vertically from top to bottom in several places appears to reduce circling roots capable of forming stem girdling roots. But slicing in the manner described in this study did little to reduce the descending root defects. Index words: circling roots, root defects, adventitious roots, stem-girdling roots, root flare, trunk flare, root number, nursery stock quality, air root-pruning containers. Species used in this study: Cathedral Oak® (Quercus virginiana Mill. ‘SNDL’ Cathedral Oak®). J. Environ. Hort. 27(1):12–16. March 2009 Propagation of Selected Clones of Eastern Redbud (Cercis canadensis) by Stem Cuttings1 John M. Wooldridge2, Frank A. Blazich3, and Stuart L. Warren4 Department of Horticultural Science North Carolina State University Raleigh, NC 27695-7609 Abstract Two experiments, one utilizing softwood cuttings and the other semi-hardwood cuttings, were conducted to investigate the influence of growth stage and auxin treatment on rooting four related clones of eastern redbud (Cercis canadensis L.). The four clones were ‘Flame’ (C. canadensis L. ‘Flame’), dwarf white, and two selections (NC99-6-1 and NC99-6-2) of an F1 generation derived from a cross of ‘Flame’ and dwarf white. At each growth stage, rooting responses of the clones varied and were influenced greatly by auxin treatment, demonstrating the variable rooting potential of the genotypes. In both studies, ‘Flame’ rooted well [63% rooting in the softwood study when treated with the potassium (K) salt (K-salt) of indolebutyric acid (IBA) at 5000 mg·L–1 (ppm), 83% rooting when treated in the semi-hardwood study with K-IBA at 10,000 mg·L–1], indicating stem cuttings may be a commercially feasible means of propagation for ‘Flame.’ Softwood cuttings of dwarf white (46%) and NC99-6-2 (75%) rooted best when treated with K-IBA at 15,000 mg·L–1, whereas softwood cuttings of NC99-6-1 rooted best (46%) when treated with K-IBA at 10,000 mg·L–1. Dwarf white and the F1s rooted poorly in the semi-hardwood study. Index words: adventitious rooting, auxin, K-indolebutyric acid, Fabaceae. Species used in this study: eastern redbud (Cercis canadensis L.). J. Environ. Hort. 27(1):17–23. March 2009 Evaluation of Systemic Insecticides for Potato Leafhopper Control in Field-Grown Red Maple1 J.B. Oliver2, D.C. Fare3, N. Youssef4, M.A. Halcomb5, M.E. Reding6, and C.M. Ranger7 Tennessee State University, School of Agriculture and Consumer Sciences Otis L. Floyd Nursery Research Center, McMinnville, TN 37110 Abstract Systemic insecticides and application methods were evaluated in two trials that began in 2005 and 2006 for control of potato leafhopper (Empoasca fabae [Harris]) on four red maple (Acer rubrum L.) cultivars and rated annually through 2007. Treatments evaluated in this study included surface drenches of imidacloprid plus cyfluthrin (Discus) or imidacloprid plus bifenthrin (Allectus SC), clothianidin (Arena 50WDG), dinotefuran (Safari 20SG), or thiamethoxam (Flagship 25WG); soil inserted treatments of imidacloprid formulated as an experimental tablet or as an experimental gel; or a plant root dip of Discus + Terra-Sorb hydrogel. In the 2005 trial, a one-time drench of Discus or two imidacloprid tablets significantly reduced leafhopper damage to red maple for a 3-year period. In the 2006 trial, a one-time drench of Allectus, Discus, Arena, Flagship, and Safari significantly reduced leafhopper damage for 2 years. In most cases, the Discus drench and root dip treatments were initially more effective than the imidacloprid tablets or the gel treatment. However, in general, the efficacy of imidacloprid tablet or gel treatments increased in subsequent years. Two imidacloprid tablets were more effective than one. Likewise, higher imidacloprid drench rates were more effective than lower rates. Most insecticide treatments significantly increased red maple trunk diameter, although this effect varied with cultivar and time. Allectus and Discus drench treatments significantly increased the branch and internode length of ‘Franksred’ maple in the 2005 trial. Results of this study indicate long-term potato leafhopper control with systemic insecticides and enhanced growth in red maple. Index words: leafhopper, Empoasca fabae, Acer rubrum, neonicotinoid, insecticide, tree growth. Species used in this study: red maple (Acer rubrum L.) cultivars ‘Autumn Flame’, ‘Fairview Flame’, ‘Franksred’, and ‘October Glory’. Chemicals used in this study: experimental imidacloprid tablet formulation (currently marketed as CoreTect); experimental imidacloprid gel formulation; imidacloprid + cyfluthrin (Discus); imidacloprid + bifenthrin (Allectus SC); clothianidin (Arena); dinotefuran (Safari); thiamethoxam (Flagship); potassium polyacrylamide acrylate copolymer (Terra-Sorb Fine Hydrogel). J. Environ. Hort. 27(1):24–30. March 2009 Impact of Improved Landscape Quality and Tree Cover on the Price of Single-Family Homes1 Andrea Stigarll and Emmett Elam2 Department of Agricultural and Applied Economics 301 Ag. Sciences Bldg., Texas Tech University, Lubbock, TX 79409 Abstract Impacts of the quality of landscaping and percentage of tree cover on home prices were estimated from a sample of 75 home sales within the Melonie Park neighborhood in Lubbock, TX, from 2003 to 2005. Estimates were derived using a regression of house sale price on house characteristics, landscape quality, and tree cover. Homes that improved landscaping from average quality to good or excellent quality increased selling price by 5.7 and 10.8%, respectively. Approximately 30% of the increase in sale value was accounted for by added tree cover. The results show that each $1.00 invested in upgrading an average landscape to excellent quality returns $1.35 in added property value. Index words: hedonic model, home prices, landscape investment, landscape quality, tree cover. J. Environ. Hort. 27(1):31–36. March 2009 Flowering, Fecundity, Seed Germination, and Seed Viability of Viburnum opulus L. Cultivars1 Janine R. Conklin2 and James C. Sellmer3 Department of Horticulture Pennsylvania State University University Park, PA 16802 Abstract Mature specimens of Viburnum opulus and cultivars ‘Leonard’s Dwarf’ and ‘Roseum’ were assessed over 2 years for flower and seed production, seed germination, and seed viability as determined by a tetrazolium test to understand their invasive potential. ‘Aureum’, ‘Compactum’, ‘Losely’s Compact’, ‘Nanum’, and ‘Xanthocarpum’ were also tested for germination and viability of seeds. Cultivars differed in flower and seed production, seed germination, and seed viability. ‘Roseum’ prolifically produced highly viable seed that germinated at moderate rates under greenhouse conditions (8,354, 100%, and 73%, respectively). Viburnum opulus and ‘Leonard’s Dwarf’ produced fewer viable seed which showed moderate to low germination rates (609, 100%, and 53%; 712, 100%, and 5%, respectively). ‘Aureum’ and ‘Xanthocarpum’ seeds germinated at moderate rates (55 and 25%, respectively) and were highly viable (100%). ‘Compactum’, ‘Losely’s Compact’, and ‘Nanum’ germinated at low rates or failed to germinate (0, 0, and 5%, respectively), yet seeds were moderately viable (37, 65, and 55%, respectively). Seeds of all cultivars germinated at low rates or failed to germinate at both outdoor sites (0 to 5%) which suggests these plants may be weakly invasive. Short-term studies on biological traits such as these provide only limited information to assess the invasive potential of cultivars. Index words: European cranberrybush viburnum, invasive, greenhouse, landscape, forest, ornamentals. Species used in this study: European cranberrybush viburnum (Viburnum opulus L.) and cultivars ‘Aureum’, ‘Compactum’, ‘Leonard’s Dwarf’, ‘Losely’s Compact’, ‘Nanum’, ‘Roseum’, and ‘Xanthocarpum’. Chemicals used in this study: Roundup (glyphosate), N-(phosphonomethyl)glycine; Basamid (dazomet), Tetrahydro-3, 5-dimethyl-2H-1, 3, 5-thiadiazine-2-thione; Tetrazolium Red (TTZ), 2, 3, 5-Triphenyltetrazolium chloride. J. Environ. Hort. 27(1):37–41. March 2009 Butterfly Feeding Preferences for Four Zinnia Cultivars1 Kenneth V. Yeargan2 and Sarah M. Colvin3 Department of Entomology, University of Kentucky, Lexington, KY 40546 Abstract Zinnias are recommended frequently for inclusion in butterfly gardens as nectar sources for adult butterflies, but little is known about butterfly preferences for different zinnia cultivars. We compared numbers and species of butterflies that visited four widely available zinnia cultivars: Zinnia violacea Cav. (formerly Zinnia elegans Jacq.) ‘Lilliput’, ‘Oklahoma’, ‘State Fair’, and Zinnia marylandica Spooner, Stimart, and Boyle ‘Pinwheel’. Mixed colors were used for all cultivars. Based on a total count of 2355 butterflies, representing 30 species, more than twice as many total butterflies visited ‘Lilliput’ than visited any of the other cultivars. Also, a greater number of butterfly species visited ‘Lilliput’ than visited any of the other cultivars. More than half of the counted butterflies belonged to the family Nymphalidae, with members of the families Pieridae and Hesperiidae being the second and third most frequent visitors, respectively. Index words: Lepidoptera, flower visitation, butterfly gardens. Species used in this study: Zinnia violacea Cav. ‘Lilliput’, ‘Oklahoma’, ‘State Fair’, and Zinnia marylandica Spooner, Stimart, and Boyle ‘Pinwheel’. J. Environ. Hort. 27(1):41–50. March 2009 Performance of Mycorrhizal Products Marketed for Woody Landscape Plants1 P. Eric Wiseman2, Kristen H. Colvin3, and Christina E. Wells4 Department of Horticulture, Clemson University, Clemson, SC 29634 Abstract Commercial products containing propagules of arbuscular mycorrhizal fungi (AMF) are widely marketed to improve woody plant performance in the landscape. However, the infectivity of these products has rarely been subjected to independent testing. We evaluated commercial AMF inoculants in a series of greenhouse experiments using corn (Zea mays), sorghum (Sorghum bicolor), trident maple (Acer buergerianum), and sweetbay magnolia (Magnolia virginiana) as host plants. In corn and sorghum, colonization rarely exceeded 5% when plants were treated with commercial inoculants. In contrast, viable lab-cultured inoculant of similar species composition yielded mean colonization percentages of 38 to 61%. Despite the near absence of colonization, commercial inoculants generally improved shoot growth and increased soil nutrient concentrations in a dose- dependent manner. Commercial inoculants had no effect on mycorrhizal colonization or shoot growth of trident maple or sweetbay magnolia liners. Product-treated magnolias grown from seed also developed little or no mycorrhizal colonization, whereas plants treated with a lab-cultured inoculant were 74% colonized. If commercial AMF inoculants are to receive broad acceptance as landscape soil amendments, manufacturers must demonstrate that their products can promote mycorrhizal colonization under the conditions of their intended distribution and use. Index words: corn (Zea mays), sorghum (Sorghum bicolor), trident maple (Acer buergerianum), sweetbay magnolia (Magnolia virginiana), mycorrhizal colonization, arbuscular mycorrhizal fungi. J. Environ. Hort. 27(1):51–55. March 2009 Preemergence Control of Black Cottonwood in Nursery Containers1 James E. Altland2 Application Technology Research Unit, USDA-ARS 1680 Madison Ave., Wooster, OH 44691 Abstract Two experiments were conducted to evaluate preemergence herbicides for control of black cottonwood (Populus trichocarpa) in nursery containers. In 2006, granular preemergence herbicides were applied to recently filled, weed-free containers in May just prior to seed release from mature cottonwood trees. Flumioxazin provided the most effective cottonwood control, although control with isoxaben + trifluralin, oxyfluorfen + oryzalin, and pendimethalin was also effective. In 2007, containers were filled February 15, and herbicides were applied to separate groups of containers on February 22, March 14, April 16, and May 15. Containers were over-seeded with cottonwood for a 2-week period starting on May 16. Control with most herbicides improved as the date of application neared the date of seeding. Flumioxazin provided the most effective control throughout the experiment, but control from it also improved as the date of application neared the time of seeding. Index words: woody weed species, poplar, weed control. Herbicides used in this study: Ornamental Herbicide II (OH2, pendimethalin + oxyfluorfen), N-(1- ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine + 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4- (trifluoromethyl)benzene; Rout (oryzalin + oxyfluorfen), 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide + 2- chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene; Snapshot 2.5TG (isoxaben + trifluralin), N-[3- (1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide + 2,6-dinitro-N,N-dipropyl-4- (trifluoromethyl)benzenamine; Pendulum 2G (pendimethalin); Ronstar G (oxadiazon), 3-[2,4-dichloro-5-(1- methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one; BroadStar (flumioxazin), 2-[7-fluoro- 3,4-dihydro-3-oxo-4-(2-propynyl)-2H-1,4-benzoxazin-6-yl]-4,5,6,7-tetrahydro-1H-isoindole-1,3(2H)-dione; Regal O-O (oxadiazon + oxyfluorfen); RegalKade (prodiamine), 2,4 dinitro-N3,N3-dipropyl-6-(trifluoromethyl)- 1,3-benzenediamine; RegalStar (oxadiazon + prodiamine). Species used in this study: black cottonwood (Populus trichocarpa). J. Environ. Hort. 27(1):56–62. March 2009 Production of Woody Nursery Crops in Clean Chip Residual Substrate1 Cheryl R. Boyer2, Charles H. Gilliam3, Glenn B. Fain4, Thomas V. Gallagher5, H. Allen Torbert6, and Jeff L. Sibley3 Department of Horticulture, 101 Funchess Hall, Auburn University, AL 36849 Abstract Clean chip residual (CCR) is a potential replacement for pine bark (PB) in nursery crop substrates. It is a by- product of in-field forestry harvesting practices and has been shown to produce annual plants and perennials similar in size to plants grown in PB. Studies were conducted in two locations, Auburn, AL, and Poplarville, MS, to evaluate growth of woody ornamentals grown in CCR or PB. Five species were tested; Loropetalum chinensis var. rubrum, Buddleja davidii ‘Black Knight’, Lagerstroemia indica ‘Hopi’, Lagerstroemia × fauriei ‘Natchez’, and Rhododendron indicum ‘Mrs. G.G. Gerbing’. There were few differences in plant growth indices, leaf chlorophyll content, and inflorescence number over the course of the year for all species at both sites. Percent rootball coverage was generally similar among treatments, though those grown in PB had the greatest percent rootball coverage for loropetalum and buddleja (at both sites) and azalea at Auburn. Shoot dry weight of loropetalum and crapemytrle grown in PB at Poplarville was greater than plants grown in CCR. Index words: media, forest residuals, pine, loblolly, peat moss, pine bark, sustainable, alternative, loropetalum, crapemyrtle, azalea, buddleja. Species used in this study: Loropetalum (Loropetalum chinensis var. rubrum R. Br.); buddleja (Buddleja davidii ‘Black Knight’ Franch.); crapemyrtle (Lagerstroemia indica L. ‘Hopi’ and Lagerstroemia × fauriei ‘Natchez’ Wallich ex Paxt.); azalea (Rhododendron indicum ‘Mrs. G.G. Gerbing’).