Root Growth Near Vertical Root Barriers after Seven Years

Vertical root barriers are used to redirect root growth to greater depths in the soil, thus reducing damage to the sidewalks. This study was conducted to examine root growth patterns near a variety of vertical root barriers. Thirty willow oaks (Quercus phellos) were planted in November 2000 and one of the following treatments was installed on two sides of each tree: Biobarrier, DeepRoot Universal Barrier, DeepRoot Universal Barrier with Spin Out, Tex-R, Typar Geotextile 3801, or a no-barrier control. In March 2007, the second 15-tree block was excavated to reveal the root system outside the barrier. All five root barriers significantly reduced the amount of root growth compared with the control trees. There were no differences among the products tested.

(101) Fertilizer Source Affects Nitrogen and Phosphorus Levels in Leachate from Container-grown Quercus phellos L. and Magnolia virginiana L.

Environmental concerns with nitrogen and phosphorus use at container nurseries and the subsequent effects of nutrient-laden irrigation effluent prompted this study. Bare root liners of willow oak (Quercus phellos L.) and sweetbay magnolia (Magnolia virginiana L.) were grown in #5 containers during year one and repotted into #15 containers during year two using 100% pine bark or pine bark: peat substrate (4:1 by volume). Two fertilizer sources, Osmocote 19N–2.2P–7.5K (19–5–9) or Harrell's 17N–2.2P–10.0K (17-5-12), were included in the container substrate in a fluoropolymer bag with 17 g N in each #5 container and 63 g N in each #15 container. Using a split plot design with fertilizer and media as subplots, a cyclic irrigation regime consisting of three irrigation applications spaced one hour apart was compared to a traditional irrigation regime with one irrigation application that equaled the total volume applied in the cyclic regime. Fertilizer source influenced cumulative amounts (mg/year) of ammonium-N, nitrate-N and orthophosphate in the container leachate. Nitrate-N and ammonium-N from Harrell's 17N–2.2P–10.0K fertilizer were each ≈20% higher in the container leachate from sweetbay magnolia than Osmocote 19N-2.2P-7.5K fertilizer. In the case of the willow oak, the differences were 32% and 19%, respectively. Orthophosphate averaged about 65% greater in leachate from both sweetbay magnolia and willow oak containers when grown with Osmocote compared to Harrell's fertilizer. At the end of year two, height and caliper growth were similar among treatments with both species.

Provenance and Production Location Affects Growth and Quality of Quercus phellos and Q. shumardii Seedlings

Seed origin is an important part of oak production that is often ignored by many shade tree growers when selecting material for production. Results of this study indicate interactions between seed sources and production environments have a marked effect on growth and quality of seedlings of willow (Quercus phellos L.) and shumard (Q. shumardii Buckl.) oak in the first two years of production. Seedlings from selected provenances, grown in different hardiness zones, varied more in plant height than trunk caliper and quality. Seedlings from the southern part of the native range of the two species generally grew better in both climates the first growing season. After the second season, total height growth for the various provenances indicated provenance genotype was more important than where seeds were collected. Provenances from the southern native range did not out perform those collected from the central and northern sectors. Exposing seedlings from various provenances to four environmental regiments at two production locations (MS-TN, TN-MS, MS-MS, and TN-TN; referring to year1-year 2, respectively) was more effective at detecting seedlings from provenances with broad environmental adaptation than simply comparing growth at the two locations.

Biological Responses of Red Oaks (Quercus falcata var. falcata) and Willow Oak (Quercus phellos) to Hypoxia in the Rhizosphere

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Weed Suppression for Container-grown Willow Oak Using Copper-treated Fabric Disks

A commercially available copper-treated disk was evaluated for its effect on weed suppression for container-grown willow oak (Quercus phellos L.). No weeds grew in containers where disks were used. All trees grown without disks or preemergent herbicide were dead within 6 months. Top dry weights were greater for trees grown with disks or preemergence herbicide, but root dry weights were not different.

Monografía de roble americano rojo Quercus palustris

El Roble americano rojo de los pantanos (Quercus palustris (Muench)) es un hermoso árbol de mediano tamaño, que presenta una alta tasa de crecimiento. Es apreciado y cultivado con fines ornamentales por la hermosa forma de su copa y por el color de su abundante follaje. Además, se le puede transplantar bien y es tolerante a ambientes urbanos. Esta especie pertenece al grupo de los robles americanos rojos (red oaks) el cual conforma uno de los más importantes conjuntos de especies productoras de maderas duras (Quercus rubra, Quercus velutina, Quercus shumardii, Quercus coccinea, Quercus phellos). Su madera es dura y pesada, comparable a otras del grupo de robles americanos rojos en términos de sus propiedades físico-mecánicas, pero presenta menor importancia comercial al ser comparada con la de los robles blancos.