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  • Author or Editor: David Williams x
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Growers, nurseries, landscape contractors and installers, and those responsible for maintenance have observed a trend that trees are too deep within the root ball. This study addresses the relationship between planting depth and its effect on tree survival, root growth, root architecture, and caliper growth. The experiment was initiated to determine the effect of planting depth on nursery-grown trees. Three-year-old, 2.1–2.7 m, bare-root liners of Acer platanoides `Emerald Lustre', Fraxinus americana `Autumn Purple', Fraxinus pennsylvanica `Patmore', and Gleditsia triacanthos f. inermis `Shade Master' were planted in April 2004 in a completely randomized design with 20 replications per treatment per species. The trees were selected so that the distance between the graft union and the trunk flare was consistent. Trees were planted with the graft union 15.2 cm below the soil surface, or with the base of the graft union at the finished grade or with the trunk flare at the finished grade. The trees were grown in a nursery field setting with minimal supplemental watering. There were no differences in stem caliper growth at the end of two seasons in any of the four species. Root dry mass, stem elongation, and rooting structure were determined on a representative sample of trees while others were planted into the landscape for a long-term study of the effects of the original planting depth on landscape performance.

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Five taxa of Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.], `Blue Sport', `Okefenokee', Raulston Form, `Emily', and `Rachel', and one cultivar of Leyland cypress [×Cupressocyparis leylandii (Jacks. and Dallim.) Dallim.], `Haggerston Grey', were screened for resistance to Botryosphaeria and Seiridium cankers. Treatments consisted of Seiridium unicorne (Cke. And Ell.) Sutton, Botryodiplodia Sacc. sp., Fusicoccum Corda. sp. and the non-inoculated control. After 8 weeks, plants were measured for change in caliper at the wound site, change in plant height, and length and width of surface and interior cankers. Seiridium and Botryosphaeria canker development on Atlantic white cedar taxa was not significantly different than that on Leyland cypress. Seiridium unicorne was more pathogenic than Botryodiplodia sp. and Fusicoccum sp. on Atlantic white cedar and Leyland cypress with infection percentages of 100%, 84%, and 80%, respectively. Well-defined, sunken, resinous cankers developed on Leyland cypress plants infected with Seiridium unicorne, whereas Atlantic white cedar showed no visible surface canker.

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A survey was developed evaluating the preference of consumers for purchasing three alternative Christmas tree species. Trees included: Pinus virginiana, a traditional Alabama Christmas tree; a containerized Ilex × `Nellie R. Stevens'; and a cut × Cupressocyparis leylandii. Virginia pine and leyland cypress were rated higher than the holly. The average rating on a scale of 1 to 5 for the Virginia pine and the leyland cypress was 3.75 and 3.63, respectively. Consumers rated the holly an average of 3.29. A rating of 1 indicated a strong negative response and a rating of 5 offered a strong positive response for buying the tree. The median rating for all three species was 4, indicating that 50% of the participants rated them a 4 or higher. The mode, or most frequent rating, was 5 for all three species. Although the average rating for the holly was lower than the average for the Virginia pine and leyland cypress, the holly and the leyland cypress may have a market niche with >50% of the respondents indicating that they would purchase the trees.

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Zoysiagrass (Zoysia japonica Steud.) requires few inputs and provides high-quality turf in the transition zone, but is expensive to sprig or sod. Establishment by seed is less expensive than vegetative establishment, but little is known about renovation of existing turf to zoysiagrass using seed. Two experiments were performed to determine effects of herbicides and seeding rates on establishment of zoysiagrass in Indiana and Kentucky. In the first experiment, interseeding zoysiagrass into existing perennial ryegrass (Lolium perenne L.) without the use of glyphosate before seeding resulted in 2% zoysiagrass coverage 120 days after seeding (DAS). In plots receiving glyphosate before seeding, zoysiagrass coverage reached 100% by 120 DAS. In the second experiment, MSMA + dithiopyr applied 14 days after emergence (DAE) or MSMA applied at 14+28+42 DAE provided the best control of annual grassy weeds and the greatest amount of zoysiagrass establishment. Applying MSMA + dithiopyr 14 DAE provided 7% less zoysiagrass coverage compared to MSMA applied 14 DAE at one of the four locations. Increasing the seeding rate from 49 kg·ha-1 to 98 kg·ha-1 provided 3% to 11% more zoysiagrass coverage by the end of the growing season at 3 of 4 locations. Successful zoysiagrass establishment in the transition zone is most dependent on adequate control of existing turf using glyphosate before seeding and applications of MSMA at 14+28+42 DAE, but establishment is only marginally dependent on seeding rates greater than 49 kg·ha-1. Chemical names used: N-(phosphonomethyl) glycine (glyphosate); monosodium methanearsenate (MSMA); S,S-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(triflurormethyl)-3,5-pyridinedicarbothioate (dithiopyr).

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This study was initiated to investigate the effect of pulsed XeCL excimer laser radiation (308 nm) at 25 and 50 pulses per second at radiation levels of 0, 100 mJ, 200 mJ, and 300 mJ on microorganism contamination of in vitro cultures of Heder a canariensis. Explants were cultured on Murashige and Skoog (MS) medium supplemented with 8 mg/BA and 0.2 mg/NAA. The medium was adjusted to pH 5.7. The cultures were maintained for 16-hours photoperiods at 25.5°C. One day following transfer the explants were treated with pulsed excimer laser radiation. The percentage of contamination was reduced by laser radiation treatments. The effect of 5 0 pulses of radiation was found to increase the petiole length, leaf blade width, and leaf number of explants.

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Use of seeded-bermudagrasses (Cynondon dactylon) is expanding rapidly, especially on high-use athletic fields. Previous work has defined significant differences in several parameters among cultivars. Experiments were conducted in Lexington, KY, in 2004 and 2005 to test the tolerance of the cultivars Riviera, Princess, Transcontinental, Savannah, Yukon, and the experimental line SWI 1012, with and without applications of trinexapac-ethyl to simulated athletic traffic. Plots were established in June of each year and managed as athletic field turf. Simulated traffic was applied using a Brinkman traffic simulator during high school football seasons in Kentucky at a level roughly equivalent to three games per week. Percentage of bermudagrass cover was visually rated weekly during the trafficking periods each year. Turfgrass quality was rated once before beginning traffic treatments each year. There were no consistent significant interactions (P > 0.05) among trinexapac-ethyl treatments and cultivars in either year of the study for either response variable. The main effect of cultivars was highly significant (P < 0.0001) for percentage of bermudagrass cover in both years of the study. Among cultivars, the ranges of percentage of bermudagrass cover at the end of the trafficking periods were 10.2% to 39.2% and 43.3% to 76.7% in 2004 and 2005, respectively. The main effects of trinexapac-ethyl on percentage of bermudagrass cover were significant (P < 0.0052) and more pronounced in 2004. Significant differences (P < 0.0200) were also recorded in 2005. Applications of trinexapac-ethyl resulted in increased tolerance to simulated traffic and improved turfgrass quality. Under the conditions of this study, data indicate that both cultivars and regular applications of trinexapac-ethyl have significant effects on overall turfgrass quality and the tolerance of these seeded bermudagrasses to simulated traffic.

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Abstract

Operation management techniques, such as linear programming (LP), can provide producers and managers with greater quantities of information and, from this, more informed, up-to-date decisions can be made. Linear programming techniques were applied to data from ten container plant nurseries to determine possible production systems, their inputs, and to maximize profit. Models were developed for large (average, 27 ha) and small (average, 5 ha) container nurseries. Plant type and container size were used interactively as decision variables (activities) in the models. The small nursery model had 44 plant type alternatives and the large nursery model had 87. Resources included in the constraints were equipment, materials, and labor used to produce each plant type. The actual constraint values determined from survey information are provided, as well as a multiperiod model and a theoretical model.

Open Access

Callery pear (Pyrus calleryana) is an invasive tree across much of the eastern United States that can form dense thickets, and tree branches and stems are often covered in sharp thorns. Landowners and land managers attempting to manage callery pear infestations are faced with the challenge of killing and/or removing the trees while also avoiding thorn damage to equipment, which can lead to wasted time and increased costs. We evaluated fire as management tool to reduce the likelihood of equipment damage from callery pear thorns. Branches were collected in the field from callery pear trees that were killed by herbicide, and also from untreated trees, and half the branches from each group were then burned with a propane garden torch to simulate a low-intensity prescribed fire. After treatment, all branches were returned either to an old field or forest floor for 1 year, after which thorn puncture strength was evaluated and compared with freshly cut thorns. Herbicide treatment and location did not affect thorn strength, but burning reduced the likelihood that thorns would puncture a tire. Fire increased tip width, which reduced thorn sharpness. Burning also reduced wood strength, and fungi proliferated on burned thorns after 1 year in the field or forest. Both factors likely contributed to decreasing thorn strength and probability of puncture. Our results show that using prescribed fire as a management tool can weaken callery pear thorns and dull their tips, reducing the chance of equipment damage and costs associated with clearing land of this invasive species. Leaving cut callery pear trees on the ground for 1 year increased fungal colonization, which may also reduce thorn damage. Prescribed fire can be part of an effective integrated management plan for this, and possibly other, thorny invasive flora.

Open Access