ln Spring 1993, red oaks (Quercus rubra) were propagated from seed. From June through October, plants were fertilized twice daily with 1.4 liters of 20N–10P–20K water-soluble fertilizer solution at concentrations of 0, 25, 50, 100, 200, or 400 ppm N. Destructive harvests were conducted six times at intervals from June through Dec. 1993. Leaf area, stem height, root length, root area, and dry weights of roots, stem, and leaves of harvested plants were measured and tissue nutrient concentrations were analyzed. There was no relationship between whole-plant N concentration and total plant biomass (r = 0). However, there were some linear relationships between total plant N and total plant biomass for an individual fertilizer treatment. Biomass allocation between root, stems, and leaves was very consistent across all fertilizer levels at any one harvest. Percent total N in roots, stems, and leaves also was fairly consistent across fertilizer levels. This was true at each harvest, except the first two, in which a greater percentage of total N was partitioned to the leaves and a smaller percentage was partitioned to the roots in the high (100, 200, 400 ppm N) fertilizer treatments. Whole-plant K concentrations increased with increasing fertilizer level, but decreased over time. Whole-plant P concentrations increased linearly with whole-plant dry weight in the higher (100, 200, 400 ppm N) fertilizer treatments.
Jill C. Larimer and Dan Struve
Thomas J. Tworkoski, Michael E. Engle, and Peter T. Kujawski
A polypropylene fabric containing control-release pellets of the herbicide, trifluralin, can be oriented in the soil to regulate the distribution of plant roots. In 1990, trenches were dug near 10-year-old red oak (Quercus rubra L.) and 10-year-old yellow poplar (Liriodendron tulipifera L.) and fabric containing trifluralin control-release pellets and polypropylene fabric alone were installed vertically to redirect root growth. Roots grew alongside trifluralin fabric and fabric alone and did not penetrate either fabric 38 months after installation. Shoot growth of yellow poplar was reduced about 47% each year by the trifluralin fabric treatment compared to control. Red oak shoot growth was not affected by trifluralin fabric. Leaf water potential was not affected by treatment in either species. Trifluralin residues in trifluralin fabric decreased from 23.3% to 22.0% from July 1990 to October 1993. During this time, trifluralin levels increased from 0.4 to 3.6 mg·kg-1 in soil sampled 0 to 15 cm below trifluralin fabric. These results suggest that controlled-release trifluralin will provide persistent inhibition of root and shoot growth of some species and will not migrate significantly in the soil. Chemical names used: α,α,α-trifluoro-2,6-dinitro-N-N-dipropyl-p-toluidine (trifluralin).
Robert M. Augé, Xiangrong Duan, Jennifer L. Croker, Craig D. Green, and Will T. Witte
We compared the potential for foliar dehydration tolerance and maximum capacity for osmotic adjustment in twelve temperate, deciduous tree species, under standardized soil and atmospheric conditions. Dehydration tolerance was operationally defined as lethal leaf water potential (Ψ): the Ψ of the last remaining leaves surviving a continuous, lethal soil drying episode. Nyssa sylvatica and Liriodendron tulipifera were most sensitive to dehydration, having lethal leaf Ψ of –2.04 and –2.38 MPa, respectively. Chionanthus virginiana, Quercus prinus, Acer saccharum, and Quercus acutissima withstood the most dehydration, with leaves not dying until leaf psi dropped to –5.63 MPa or below. Lethal leaf Ψ (in MPa) of other, intermediate species were: Quercus rubra (–3.34), Oxydendrum arboreum (–3.98), Halesia carolina (–4.11), Acer rubrum (–4.43), Quercus alba (–4.60), and Cornus florida (–4.88). Decreasing lethal leaf Ψ was significantly correlated with increasing capacity for osmotic adjustment. Chionanthus virginiana and Q. acutissima showed the most osmotic adjustment during the lethal soil drying episode, with osmotic potential at full turgor declining by 1.73 and 1.44 MPa, respectively. Other species having declines in osmotic potential at full turgor exceeding 0.50 MPa were Q. prinus (0.89), A. saccharum (0.71), Q. alba (0.68), H. carolina (0.67), Q. rubra (0.60), and C. florida (0.52). Lethal leaf Ψ was loosely correlated with lethal soil water contents and not correlated with lethal leaf relative water content.
Benjamin L. Green, Richard W. Harper, and Daniel A. Lass
Urban foresters must be able to accurately assess costs associated with planting trees in the built environment, especially since resources to perform community forest management are limited. Red oak (Quercus rubra) and swamp white oak (Q. bicolor) (n = 48) that were produced using four different nursery production systems—balled and burlapped (BNB), bare root (BR), pot-in-pot container grown (PIP), and in-ground fabric (IGF)—were evaluated to determine costs of planting in the urban environment. Costs associated with digging holes, moving the trees to the holes, and planting the trees were combined to determine the mean cost per tree: BNB trees cost $11.01 to plant, on average, which was significantly greater than PIP ($6.52), IGF ($5.38), and BR ($4.38) trees. Mean costs for BR trees were significantly lower than all other types of trees; IGF trees were less expensive to plant (by $1.14) than PIP trees, but this difference was not statistically significant (P = 0.058). Probabilities that cost per tree are less than specific values also are calculated. For example, the probabilities that IGF and BR can be planted for less than $8.00 per tree are 1.00. The probability that a PIP can be planted for less than $8.00 is 0.86, whereas the probability for a BNB tree is just 0.01. This study demonstrates that the cost of planting urban trees may be affected significantly in accordance with their respective nursery production method.
J. Roger Harris, Jody Fanelli, and Paul Thrift
Description of early post-transplant root growth will help formulate best transplanting strategies for landscape trees. In this experiment, the dynamics of early root system regeneration of sugar maple (Acer saccharum Marsh. `Green Mountain') and northern red oak (Quercus rubra L.) were determined. Field-grown 4-year-old trees were transplanted bare-root into outdoor root observation containers (rhizotrons) in Oct. 1997, Nov. 1997, or Mar. 1998. All trees were grown in the rhizotrons until Oct. 1998 and then transplanted, with minimally disturbed rootballs, to field soil and grown for an additional two years. October-transplanted trees of both species began root regeneration earlier and regenerated more roots, as judged by accumulated root length on rhizotron windows, than Nov.- or March-transplanted trees. Median date for beginning root extension for sugar maples was 48, 22, and 0 days before budbreak for October-, November-, and Marchtransplanted trees, respectively. Median date for beginning root extension for northern red oak was 4, 21, and 14 days after budbreak for October-, November-, and Marchtransplanted trees, respectively. Height and trunk diameter growth were similar for all treatments within each species for 3 years after application of treatments. Early fall transplanting will result in earlier first season post-transplant root growth for sugar maple and northern red oak. Earlier post-transplant root growth will likely increase resistance to stress imposed by harsh landscape environments.
Chris Starbuck, Daniel K. Struve, and Hannah Mathers
Two experiments were conducted to determine if 5.1-cm-caliper (2 inches) `Summit' green ash (Fraxinus pensylvanica), and 7.6-cm-caliper (3 inches) northern red oak (Quercus rubra) could be successfully summer transplanted after being heeled in pea gravel or wood chips prior to planting in the landscape. Spring harvested trees of each species were either balled and burlapped (B&B) or barerooted before heeling in pea gravel or wood chips. Compared to B&B `Summit' green ash, bareroot stock had similar survival and shoot extension for three growing seasons after summer transplanting. Bareroot and B&B northern red oak trees had similar survival and central leader elongation for 3 years after summer transplanting. In the third year after transplanting, northern red oak bareroot trees heeled in pea had smaller trunk caliper than B&B trees heeled in wood chips. These two taxa can be summer transplanted B&B or bareroot if dormant stock is spring-dug and maintained in a heeling-in bed before transplanting. This method of reducing transplant shock by providing benign conditions for root regeneration can also be used to extended the planting season for field-grown nursery stock; the method is called the Missouri gravel bed system.
Hannah M. Mathers, Elizabeth Grosskurth, Michele Bigger, Luke Case, and Jenny Pope
Currently, the majority of tree liners used in the Ohio nursery industry are imported, mainly from the West Coast. The Ohio growing season is 156 days, whereas the Oregon season is 225 days. We are developing an Ohio liner production system, utilizing a retractable roof greenhouse (RRG) that extends the growing season. Liners grown in a RRG have shown greater caliper, height, and root and shoot dry weight than those grown outside of a RRG (Stoven, 2004). The objective of this research was to compare the growth of RRG-grown liners, outdoor-grown liners, and West Coast-grown liners when planted in the field. Four tree species [Quercus rubra, Malus `Prairifire', Acer ×freemannii `Jeffersred' (Autumn Blaze®), and Cercis canadensis] were started from either seed or rooted cuttings in early 2003. They were grown in a glass greenhouse and then moved to their respective environments in March (RRG) and May (outside). In Oct. 2003, the Ohio-grown liners were planted in the field at the Waterman Farm of The Ohio State University, Columbus. In Spring 2004, liners from the West Coast were purchased and planted in the same field setting. Caliper and height were measured in June and Sept. 2004. After one season in the field, trees grown from the RRG and outdoor environments resulted in greater height and caliper than the West Coast liners in Malus, Acer, and Cercis. Acer liners from Oregon had a greater increase in height from June to September than those grown outdoors or in the RRG. Quercus liners from the RRG and outdoor environments displayed greater caliper growth and growth in height than those from the West Coast. Across all species, liners grown from the RRG had the greatest increase in caliper growth.
Alexander R. Kowalewski, Douglas D. Buhler, N. Suzanne Lang, Muraleedharan G. Nair, and John N. Rogers III
Previous research has shown that maple (Acer spp.) leaf litter resulted in fewer common dandelions (Taraxacum officinale) when mulched into established turfgrass. However, the leaves used in that research may have contained herbicide residues and were separated by genus, not species. Our research compared the effects of pesticide-free mulched maple and oak (Quercus spp.) leaves on dandelion populations in an established kentucky bluegrass (Poa pratensis) stand maintained as a residential lawn on sandy loam soil. The objectives of this study were to quantify the effectiveness of maple or oak leaf mulches as an organic common dandelion control method and to identify which maple species and rates (particle size and rate per unit area) provided the most effective control. The experimental design was a randomized complete block with treatments arranged as a 5 × 2 × 2 + 1 factorial, with tree leaf species, leaf particle size, leaf application rate, and control as main factors. Leaf species were red maple (Acer rubrum), silver maple (A. saccharinum), sugar maple (A. saccharum), high sugar content sugar maple, and red oak (Quercus rubra). Particle sizes were coarse (0.4–1.0 inch2) and fine (≤0.2 inch2), and application rates were low (0.5 kg·m−2) and high (1.5 kg·m−2). Mulch applications were made in Fall 2003 and 2004 and data were collected beginning in Spring 2004 on kentucky bluegrass spring green-up, and common dandelion plant counts. The high application rate, regardless of tree genus or species, resulted in the highest green-up ratings. Common dandelion plant counts after one (2003) and two (2003 and 2004) mulch applications at the high rate showed that up to 80% and 53% reduction was achieved, respectively. Results indicate that mulching leaves regardless of genus (oak or maple) or maple species into established turfgrass as a leaf litter disposal method will increase spring green-up and contribute to a reduction in common dandelion population.
Luke Case, Hannah Mathers, and Elizabeth Grosskurth
Many Ohio growers import liners from the West Coast due to the increased growing season on the West Coast. Lengthening the season in Ohio may provide a way for Ohio growers to produce liners of their own. Retractable roof greenhouses (RRG) are one possible way to extend the growing season in Ohio. Research done previously at The Ohio State University suggests that retractable roof greenhouses do in fact lengthen the growing season, and tree liners can be produced using RRG. The objectives of this study were: 1) to determine the optimal growing environment from three different environments; and 2) to determine the optimal species for tree liner production in Ohio. In Oct. 2004, 180 liners each of Cladrastis kentuckea, Quercus rubra, Stewartia pseudocamellia, Syringa reticulata, and Tilia cordata were upshifted to 3-gallon pots. In Mar. 2005, 90 of each species were transferred to either a flat roof retractable house (FRRG), peak roof retractable house (PRRG), or polyhouse. Growth was measured in Mar. (initial), June, Aug., and Oct. 2005 by taking leaf area, shoot and root dry weights, height, and caliper. There were no differences across species and dates between the environments for any of the parameters measured. Tilia showed the greatest increase in growth from June to October in all the parameters measured except leaf area. Cladrastis showed the greatest increase in leaf area from June to October. There were species by date interactions. Quercus had the greatest root weight in October. Syringa and Quercus were not significantly different from each other and had the highest shoot weights and leaf areas in October. Tilia, Quercus, and Syringa had the highest calipers in October.
Lisa Richardson-Calfee, J. Roger Harris*, and Jody Fanelli
Seasonal effects on transplant establishment of balled-and-burlapped (B&B) shade trees are not well documented. Early post-transplant root growth and above-ground growth over 3 years were therefore documented 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. However, new root growth was evident when subsamples were excavated the following April for November-transplanted trees of both species, 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, had grown more roots by spring bud break than March-transplanted trees. 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 transplanting had little effect on height growth, but November transplanting resulted in greater trunk diameter increase. However, considering the mortality rate of November-transplanted willow oak, March may be a better time to transplant willow oak in climates similar to southwest Virginia.