J. Roger Harris's research while affiliated with Virginia Polytechnic Institute and State University and other places

Publications (83)

Article
Trees with root systems established well below grade due to deep planting or soil disturbance are common in urban landscapes, yet the long term effects of buried trunks and subsequent remediation strategies, such as root collar excavation are poorly documented. We evaluated the consequences of deep planting over a 10-year period on tree growth and...
Article
Urban land development frequently destroys soil structure and removes organic matter, limiting tree growth. Soil rehabilitation has potential to improve soil quality but the long-term effectiveness and consequences for tree growth are poorly documented. We evaluated growth, canopy development, and physiological response of five tree species over si...
Article
Pine tree substrate (PTS) is a relatively new alternative to the commonly used pine bark and peat-based substrates for container crop production. Physical and chemical properties of freshly manufactured PTS have been studied; however, this new substrate will sometimes be manufactured and stored for later use by growers. The objective of this resear...
Article
There is increasing interest in amending degraded soils with organic matter to improve soil quality, especially in urban areas where rehabilitation of damaged soils may enhance tree growth and provision of ecosystem services. To assess the potential of such organic amendments for producing a sustained alteration in soil biological characteristics,...
Conference Paper
There is increasing interest in amending degraded soils with organic matter to improve soil quality and increase capacity to support tree growth, especially in urban areas where rehabilitation of damaged soils may enhance tree growth and provision of ecosystem services. To assess the potential of such organic amendments for producing a sustained al...
Article
Growth rates of nursery-grown oaks (Quercus L.) vary considerably, and many oak species are not commonly grown because of slow growth when young. A method for rapid screening of young oak seedlings to predict potential growth in a production nursery was investigated. Acorns from single maternal trees of four Virginia-native oak species, Quercus mon...
Conference Paper
Growth rates of nursery-grown oaks are reported to vary considerably, and otherwise desirable species are not commonly grown because of slow growth when young. In this study, we investigated a method for rapid screening of very young oak seedlings for predicting potential for growth in a production nursery. Acorns from single maternal trees of Quer...
Article
Root flares of landscape trees are increasingly found to be much deeper than their forest counterparts, indicating that their root systems have been situated deeper in the soil. Planting deeply in production containers contributes to this phenomenon, yet the consequences of deep planting in production containers or the consequences of any adjustmen...
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This review examines current understandings of how the belowground characteristics of urban settings affect tree roots as well as how tree roots contribute to biogeochemical processes in this belowground environment. Soil characteristics common to the urban environment include soil compaction and other physical impediments to root exploration, elev...
Conference Paper
This study was conducted to determine how pine tree substrate (PTS) pH was affected by storage time and lime and peatmoss amendments. PTS was manufactured (April 2009) from freshly harvested loblolly pine trees (Pinus taeda L.), chipped, and hammermilled to two sizes, 4.76 mm, and 15.88 mm; the former substrate was unamended and the latter substrat...
Conference Paper
Benzyladenine, 6-BA (Configure, Fine Americas, Inc.), was applied as a foliar spray to Gaillardia aristata ‘Gallo Yellow,’ Gaura lindheimeri 'Siskiyou Pink,’ Geranium ‘Rozanne,’ Penstemon digitalis ‘Husker Red,’ Phlox paniculata ‘Laura,’ Veronica longifolia ‘Icicle,’ and four Echinacea cultivars, Fragrant Angel, Merlot, Sombrero Hot Pink, and Tiki...
Conference Paper
Higher education has enthusiastically adopted the concept and practice of campus-based civic engagement. Virginia Tech is a member of Campus Compact, a national coalition of more than 1,100 college and university presidents (representing over six million students), that is dedicated to promoting service, civic engagement, and service-learning in hi...
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Knowledge of the extent and distribution of tree root systems is essential for managing trees in the built environment. Despite recent advances in root detection tools, published research on tree root architecture in urban settings has been limited and only partially synthesized. Root growth patterns of urban trees may differ considerably from simi...
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ADDITIONAL INDEX WORDS. irrigation, fertilization, surface water management, pathogens, Moodle, distance-learning modules SUMMARY. Increasing environmental concerns and legislation in many states and in other countries require that we take a more comprehensive sustainable ''best management'' approach to production techniques in nursery and greenhou...
Article
Root system regeneration after transplanting of large trees is key to successful establishment, yet the influences of different production systems and transplant timing on root growth remain poorly understood. Patterns of new root production and mortality were therefore measured for 1 year after transplanting landscape-sized Acer saccharum Marsh. (...
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Stormwater management that relies on ecosystem processes, such as tree canopy interception and rhizosphere biology, can be difficult to achieve in built environments because urban land is costly and urban soil inhospitable to vegetation. Yet such systems offer a potentially valuable tool for achieving both sustainable urban forests and stormwater m...
Conference Paper
Land development is accompanied by construction activities that damage soil structure, remove organic matter, and subsequently can reduce tree survival and establishment, slow growth rates and reduce ultimate canopy cover. Soil rehabilitation protocols are needed to assist arborists, landscape contractors, landscape architects, developers and plann...
Conference Paper
Pine tree substrate (PTS), a relatively new substrate for container-grown plants, is manufactured by chipping, then milling, pine (P. taeda) logs. Nitrification in PTS, pine bark (PB), and a peat-based substrate (PL) was studied by measuring nitrate accumulation biweekly for 12 weeks. Treatments were: 1) PTS without lime (PTS), 2) PTS with 1.8 kg·m...
Conference Paper
College and university curricula often offer courses via the traditional classroom format. Due to the nature of a landscape contracting curricula, courses are most effective when they combine fundamental information of a classroom format with practical experience garnered in an “on-site” or a lab setting. Landscape contracting topics such as planti...
Conference Paper
Mountain laurel, Kalmia latifolia, is an evergreen woody shrub in the family Ericaceae, and is found in the entire eastern portion of the United States from southwestern Maine to northern Florida. Most mountain laurel germplasm used for breeding purposes in the U.S. is from the northern portions of its range. Our research is directed towards breedi...
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Recent research has improved our understanding of how structural roots of landscape trees respond to being located abnormally deep in the soil profile. This condition is widespread among landscape trees and may originate during nursery production, at transplanting into the landscape, or when construction fill or sediment deposits bury root systems...
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Global land use patterns and increasing pressures on water resources demand creative urban stormwater management. Strategies encouraging infiltration can enhance groundwater recharge and water quality. Urban subsoils are often relatively impermeable, and the construction of many stormwater detention best management practices (D-BMPs) exacerbates th...
Article
The combined effects of phenological growth stage of a tree (e.g., bud break or bud set) and production method on plant response to transplanting are not well documented. This experiment therefore examined shoot extension, trunk diameter increase, and new root length production in balled-and-burlapped (B&B) and pot-in-pot (PIP) sugar maples (Acer s...
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Recentinterestintheuseofwoodsubstratesinhorticulturecropproductionhas justified the need for determining fertilizer requirements in these substrates compared with traditional pine bark (PB) and peatmoss substrates. The objective was to determine the response of japanese holly (Ilex crenata Thunb. 'Compacta') and azalea (Rhododen- dron obtusum Planc...
Article
Today's urban forest increasingly consists of planted trees, especially as native forest fragments yield to urban sprawl. These trees are usually larger (over 2-m tall) than typical reforestation trees and grow very little for the first few years after planting. Stressful urban sites exacerbate this effect and many practitioners hope to shorten the...
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Arborists assume that pruning can help reduce the risk of tree failure by reducing the pressure exerted on trunks by wind (drag-induced bending moment), but there are few studies that quantify this effect. We simulated wind by driving trees in the back of a pickup truck from 0 to 24.5 m/s (0 to 55 mph) and measured drag-induced bending moment as we...
Article
Urban trees are frequently planted with their root collars and structural roots buried well below soil grade, either because of planting practices, nursery production practices, or both. These deeply planted structural roots can impair tree establishment and are thought to reduce tree growth, lifespan, and stability, although research has provided...
Article
In light of the risk of litigation following damage related to tree failure in urban and suburban settings, more empirical data related to free risk assessment are needed. We measured drag and drag-induced bending moment (M) and calculated drag coefficient (C-D) and trunk stress (sigma) for three deciduous trees at wind speeds up to 22.4 m/s. We me...
Conference Paper
Urbanization disrupts natural soil profiles, increases impervious surfaces and decreases vegetative cover. The resulting increase in runoff can impair aquatic habitats, prevent groundwater recharge, and adversely affect water quality. Because urban land can also be scarce and valuable, there may be little space for conventional stormwater managemen...
Article
Fundamental information regarding posttransplant root and shoot growth dynamics is needed to better understand transplant establishment. Seasonal patterns of root, shoot, and trunk growth of balled-and-burlapped and pot-in-pot (PIP) sugar maples (Acer saccharum Marsh.) transplanted at leaf drop (Nov. 2000), late fall (Dec. 2000), early spring (Mar....
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Full-text available
Landscape trees typically grow slowly for several years after transplanting. We investigated whether fertilization could speed tree growth during this establishment period, which fertilization regimes were most effective, and whether fertilization interacted with irrigation. Fifty-four each of landscape-sized, balled-and-burlapped red maple (Acer r...
Article
Sulfur (S) is essential to the growth of higher plants; however, research on S fertilizer requirements for container-grown nursery tree species has not been established. The purpose of this study was to determine the substrate solution S concentration that maximizes the growth of container-grown pin oak (Quercus palustris Münchh) (pin oak-K 2SO 4 e...
Article
Substrates of container-grown plants are commonly preplant amended with sulfated micronutrients to supply micronutrients. However, the cause for the increased growth may be due to micronutrient addition or other factors such as S addition or substrate acidification. Container-grown pin oak (Quercus palustris Müench) and japanese maple (Acer palmatu...
Article
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 tra...
Article
Prudent landscape professionals can enhance chances for successful establishment by timing tree transplant operations to coincide with ideal seasonal conditions. However, transplant timing is usually determined by economic factors, resulting in trees being transplanted at times that are unfavorable for their survival and growth. Knowledge of the ef...
Article
Mountain laurel (Kalmia latifolia L.) is a common native shrub in the Eastern United States; however, this species can be difficult to establish in landscapes. Two experiments were conducted to test the effects of transplant season and container size on landscape establishment of Kalmia latifolia L. ‘Olympic Wedding’. In experiment one, 7.6 liter (...
Article
Mountain laurel (Kalmia latifolia L.) is a common native shrub in the Eastern United States; however, this species can be difficult to establish in landscapes. Two experiments were conducted to test the effects of transplant season and container size on landscape establishment of Kalmia latifolia L. 'Olympic Wedding'. In experiment one, 7.6 liter (...
Article
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 b...
Article
Seasonal effects on transplant establishment of balled-and-burlapped (B&B) shade trees are not well documented. Early post-transplant root growth and aboveground growth over a 3-year period were therefore determined for November-and March-transplanted northern red oak (Quercus rubra L.) and willow oak (Q. phellos L.). Survival of red oak was 100% f...
Article
Newly transplanted container-grown landscape plants are reported to require very frequent irrigation. However, container nurseries in the U.S. commonly use growing substrates that are mostly bark, even though the contribution of bark-based growing substrates to water relations of transplanted root balls is unknown. Therefore, a field experiment was...
Article
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 bar...
Article
Rapid posttransplant root growth is often a determining component of successful establishment. This study tested the effect of transplant timing on first-season root growth dynamics of bare-root Turkish hazelnut trees. Trees were either harvested and planted in the fall (F-F), harvested in the fall and planted in the spring after holding in refrige...
Article
Two experiments tested the effects of root pruning on growth during first-season production of pin oak (Quercus palustris Muenchh.). Experiment one tested the effect of root pruning developing radicles at 5, 10, or 15 cm (2, 4, or 6 inches) below the substrate surface. After 11 weeks, total root length was not affected by root pruning, but root-pru...
Article
The influence of pre-measurement storage length and season of harvest of stem segment samples on hydraulic conductance and percentage embolism was determined for two tree species because no published guidelines exist concerning storage. Stem sections from Fraxinus americana L. 'Autumn Applause' (white ash) and Acer rubrum L. x saccharinum L. 'Autum...
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Root severance during field harvesting alters the water status of a tree, resulting in water stress and reduced post-transplant growth. Two experiments, using Acer rubrum L. (red maple), determined the influence of root severance at harvest on sap flow and xylem embolism. Trees 1.5-1.8 m tall (4 years old) were utilized in the first experiment, and...
Article
Use of polymer-coated fertilizers (PCFs) is widespread in the nursery and greenhouse industries. Temperature is the main factor affecting nutrient release from PCFs, yet there are few reports that quantify temperature-induced nutrient release. Since container substrate temperatures can be at least 40 °C during the summer, this research quantified t...
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This study was conducted to determine the effects of temperature on nutrient release patterns of three polymer-coated fertilizers (PCFs), each using a different coating technology: Osmocote Plus 15N-3.93P-9.96K, Polyon 18N-2.62P-9.96K, and Nutricote 18N-2.62P-6.64K. Each fertilizer was placed in a sand-filled column and leached with distilled water...
Article
Two experiments were conducted to test the effects of early root pruning on growth of pin oak ( Quercus palustris Muenchh.). Experiment one tested the effect of radicle tip removal when radicles had reached 5, 10, or 15 cm below the substrate surface. Total root length was not affected by treatment, but root-pruned trees had more large-diameter lat...
Article
Landscape trees may take years to establish since a high percentage of the root system is lost at harvest and the transplant is often of considerable size. Establishment is often slowed because landscape site conditions are inhospitable for growth. The optimum time for transplanting is well before spring budbreak. Fall is the optimum time for trans...
Article
The objective of this study was to determine the effects of lime and micronutrient amendments on growth of seedlings of nine container-grown landscape tree species in two pine bark substrates with different pHs. Acer palmatum Thunb. (Japanese maple), Acer saccharum Marsh. (sugar maple), Cercis canadensis L. (redbud), Cornus florida L. (flowering do...
Article
Red maple (Acer rubrum L. ‘Franksred’) and sugar maple (Acer saccharum Marsh. ‘Green Mountain’) trees were grown in a 56 liter (15 gal) pot-in-pot system for two years. During the second year of production, root growth was observed through observation plates fitted into the container sidewalls, and shoot extension was periodically measured. Root gr...
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Full-text available
The objective of this study was to determine the effect of micronutrient fertilization on seedling growth in pine bark with pH ranging from 4.0 to 5.5. Koelreuteria paniculata (Laxm.) was container-grown from seed in pine bark amended (preplant) with 0, 1.2, 2.4, or 3.6 kg/m ³ dolomitic limestone and 0 or 0.9 kg/m ³ sulfate-based micronutrient fert...
Article
The objective of this study was to determine the effect of micronutrient amendments to pine bark on seedling growth over a wide pine bark pH range. Koelreuteria paniculata (Laxm.) was container-grown from seed in pine bark amended (preplant) with 0, 1.2, 2.4 or 3.6 kg/m3 (0, 2, 4, 6 lb/yd3) dolomitic limestone and 0 or 0.9 kg/m3 (1.5 lb/yd3) Microm...
Article
Root pruning field-grown trees during production can increase harvested root length, but it is a time consuming and expensive practice. Root pruning before lining out instead of during production is much faster and cheaper. This study tested the effect of root pruning red maple (Acer rubrum L.) and Washington hawthorn (Crataegus phaenopyrum (L.f.)...
Article
Humate-based products have been aggressively marketed as biostimulants that increase plant growth. Little data are available on their effect on tree establishment or their interaction with fertilizer and irrigation regimes. This experiment tested several types of biostimulants on posttransplant growth of Acer rubrum L. (red maple) and Crataegus pha...
Article
Humate-based products have been aggressively marketed as biostimulants that increase plant growth. Little data are available on their effect on tree establishment or their interaction with fertilizer and irrigation regimes. This experiment tested several types of biostimulants on posttransplant growth of Acer rubrum L. (red maple) and Crataegus pha...
Article
Although the practice of amending a pine bark substrate with lime and micronutrients is common in the nursery industry, the effect of these amendments on the growth of container-grown landscape trees has not been documented. The objective of this study was to determine the lime and micronutrient preferences for a wide range of landscape trees grown...
Article
Application of biostimulants, humate-based products marketed as aids to plant establishment, may increase early post-transplant root growth and water uptake of landscape trees. We tested three distinct types of biostimulants on root growth and sapflow of balled and burlapped red maple (Acer rubrum L. 'Franksred') trees. Treatments included: humate,...
Article
This study addresses the growth limits imposed on large landscape trees by root severance at harvest and tests the effect of rootball size on stress following root severance. Two rootball sizes and a nontreated control treatment were randomly assigned to Acer saccharum Marsh. (sugar maple) trees in four adjacent nursery rows at Waynesboro Nurseries...
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Full-text available
Humate-based products have been aggressively marketed to nursery producers as biostimulants which increase plant growth. Reports of their effect on container-grown trees in organic substrate are few. We tested four distinct types of biostimulants on top and root growth of Turkish hazelnut (Corylus colurna L.), grown in containers with pine-bark sub...
Article
The Virginia Cooperative Extension (VCE) Advanced Master Gardener-Tree Steward (AMGTS) program provides advanced training in leadership development and arboriculture to MG volunteer educators so they may expand the influence of extension through leadership in community forestry. A statewide survey of agents, MGs, and foresters served as the basis f...
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Full-text available
The effect of fall vs. spring transplanting was tested on landscape-sized Chionanthus virginicus L. at a research farm in Blacksburg, Va. Two fall transplanting dates (11 Nov. and 1 Dec. 1994) were selected so that soil temperatures were decreasing and near 10 °C for the earlier fall date (11 Nov.) and decreasing and near 5 °C for the later fall tr...
Conference Paper
Full-text available
The Virginia Cooperative Extension (VCE) Advanced Master Gardener-Tree Steward (AMGTS) program provides advanced training in leadership development and arboriculture to MG volunteer educators so they may expand the influence of extension through leadership in community forestry. A statewide survey of agents, MGs, and foresters served as the basis f...
Article
Growers report that plants on gravel bed surfaces require more frequent irrigation compared to plastic surfaces. The objective of Expt. 1 was to determine if bed surface type influenced container environment and plant growth of azalea and Japanese holly plants on plastic- or gravel-covered beds. Measurements included bed, substrate, and plant canop...
Article
Virginia Cooperative Extension's (VCE) Master Gardener!Tree Steward program (MGTS) provides advanced training in leadership development and arboriculture to Master Gardener (MG) volunteer educators so that they may expand the influence of extension through leadership in community forestry. According to a statewide survey, 70% of VCE MGs and agents...
Article
Two rootball sizes as well as a nontransplanted control were randomly assigned to Acer saccharum Marsh. (sugar maple) trees in four adjacent nursery rows at Waynesboro Nurseries in Waynesboro, Va. One size (75 cm in diameter) corresponded to the American Association of Nurserymen standards. The other rootball size was 90 cm in diameter. Trees were...
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Budget restraints force many cities to rely on volunteers for street tree irrigation. Reliable, easy to follow recommendations are needed. Using a pan evaporation model created by others, we developed a method for predicting irrigation amount and frequency for street trees and tested it on mulched, 3-in (7.5 cm) caliper, balled and burlapped Pyrus...
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Three experiments were conducted to determine the feasibility of using Biobarrier, a landscape fabric with trifluralin herbicide-impregnated nodules, of various sizes to prevent root escape of trees from the drainage holes of 56-liter containers in below-ground pot-in-pot (P&P) and above-ground Keeper Upper (KU) nursery production systems. In addit...
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The objectives of this study were to determine root and shoot growth periodicity for established Fraxinus pennsylvanica Marsh. (green ash), Quercus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish hazelnut), and Syringa reticulata (Blume) Hara `Ivory Silk' (tree lilac) trees and to evaluate three methods of root growth periodicity measu...
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Combinations of defoliation and Moisturin®, a film antitranspirant, were applied to recently transplanted Quercus coccinea (scarlet oak) trees in August and to Fraxinus pennsylvanica (green ash) and Corylus colurna (Turkish ha- zelnut) trees in the late summer and fall of 1992.For scarlet oak trees, survival was poorfor all treatments. Moisturin®tr...
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Quercus coccinea (scarlet oak), Fraxinus pennsylvanica (green ash), Corylus colurna (Turkish hazelnut) and Syringa reticulata 'Ivory Silk' (tree lilac) trees were transplanted bare-root throughout the spring and fall planting season. Post-transplant response was compared with the root growth activity of established trees at the time of transplantin...
Article
Root and shoot growth periodicity were determined for Fraxinus pennsylvanica Marsh. (green ash), Quercus coccinea Muenchh., Corylus colurna L. (Turkish hazehut) and Syriaga reticulara (Blume) Hara `Ivory Silk' (tree lilac) trees. Two methods for determining root growth periodicity using a rhizotron were evaluated. One method measured the extension...
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Newly planted trees are often moved from the full sun environment of the nursery to shady locations around buildings or in urban canyons. Trees must adapt in order to survive. An adaptive strategy for trees exposed to changing irradiance levels in forest settings is the ability to change branching habit to maximize whole tree photosynthesis. The ge...
Article
Dormancy level, days to bud break, root regrowth and rate of shoot extension were determined for 18-in seedlings of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), paper birch (Betula papyrifera Marsh.) and green ash (Fraxinus pennsylvanica Marsh.) subjected to varying durations of cold storage. Douglas fir seedlings did not break bud unless ex...
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Transplanting imposes severe physiological stress because over 95% of the root system is removed when the tree is dug. The landscape designer and contractor can make decisions that will improve the chances of success. Advantages and disadvantages of purchasing trees produced by different production methods are discussed from the landscape contracto...
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Full-text available
A DDITIONAL INDEX WORDS. nursery, container, root length, rootball, transplant SUMMARY. Two experiments tested the effects of root pruning on growth during first-season production of pin oak (Quercus palustris Muenchh.). Experiment one tested the effect of root pruning developing radicles at 5, 10, or 15 cm (2, 4, or 6 inches) below the substrate s...