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Catherine Neal

Bare-root, 4-ft whips of green ash (Fraxinus pennsylvanica `Marshall's Seedless') were planted in June 2001 in a randomized complete-block design with three trees per plot. An incomplete factorial design was used to test whether annual fertilizer rate and/or application dates affected growth. Treatments were fertilized from 0 to 4 times per year in mid-April, mid-June, mid-August, and/or mid-October. A rate of 1 lb of nitrogen (N)/1000 sq ft was used whenever fertilizer was applied to a plot. Each treatment received 0, 2, 3, or 4 lbs N/1000 sq ft/year depending on the number of applications. Caliper, height, and terminal growth were measured annually for three growing seasons. At the end of seasons 2 and 3, one plant per plot was destructively harvested and processed to obtain dry weights of shoots and roots, and the shoot to root ratio was calculated. Data were analyzed by analysis of variance with least square means contrasts. Treatment effects on top weights, root weights, and shoot to root ratios were nonsignificant. There were significant treatment differences for caliper and terminal growth in years 1 and 2, but not 3. A set of orthogonal contrasts was used to determine that the effect was due primarily to growth differences in plants receiving 2 vs. 3 or 4 lbs N/1000 sq ft/year, but that 3 vs. 4 lbs made no difference. Another set of planned, but nonorthogonal contrasts was used to compare application date effects. Plants fertilized in June were greater in caliper and terminal growth in the first 2 years than plants not fertilized in June. There were nonsignificant effects of fertilizing vs. not fertilizing in late fall or early spring.

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Faheem Aftab, Katayoun Mansouri and John E. Preece

The objectives of this research were to study the effects of three environments (lab, mist, or fog), four media treatments [perlite, vermiculte, 1 perlite: 1 vermiculite (by volume), or a control (empty flats)] and zerotol treatments on shoot forcing and subsequent transfer of explants to in vitro conditions. Stem segments from field-grown trees were cut to 40-cm lengths before being placed in flats with the media treatments. Half of the flats under mist and fog were drenched weekly with zerotol (0.18% H2O2). In a separate study, silver maple was forced under mist and drenched weekly with zerotol at 0%, 0.09%, 0.108%, 0.135%, 0.18%, 0.27%, or 0.54% H2O2. Shoots (≥5 cm) were harvested and nodal and shoot tip explants were surface disinfested and placed in vitro on DKW medium with 10-8 M thidiazuron plus 1.0 μM indolebutyric acid. Species did not interact with environment, media, or zerotol treatment, and silver maple produced a mean of 6 shoots per stem segment, while green ash produced a mean of 1.2 shoots. There was a significant interaction among perlite, vermiculite and environment, with the most shoots (6.7/stem segment) produced under mist in the perlite: vermiculite mix. Silver maple explants from the lab had only 4% microbial contamination, whereas 68% of explants from fog and 92.2% of explants from mist were contaminated. When forcing was under fog, in perlite, and drenched with zerotol, explants had a 43% rate of contamination. In a separate study, when silver maple stems were placed under mist and drenched weekly with 0.18% H2O2, 46% (18 of 39 explants) established cleanly in vitro. Contamination was higher with misted explants that were drenched with higher or lower concentrations of zerotol.

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Carolyn F. Scagel, Richard P. Regan and Guihong Bi

A study was conducted to determine whether the nitrogen (N) status of nursery-grown green ash (Fraxinus pennsylvanica ‘Summit’) trees in the autumn is related to bud necrosis during the following spring. In 2005, different rates of N from urea formaldehyde (UF) or a controlled-release fertilizer (CRF) containing ammonium nitrate were applied during the growing season to green ash trees and leaves were sprayed or not with urea in the autumn. Biomass and N content was determined in Autumn 2005 and Spring 2006, and stem biomass and bud necrosis were evaluated for necrosis in Spring 2006. Trees with low N content in Autumn 2005 grew less in Spring 2006 but bud necrosis was more prevalent on trees grown at the highest N rate. Compared with trees grown with a similar amount of N from UF, growing trees with CRF altered N allocation in 2005 and the relationship between carbon (C) and N dynamics (import, export, and metabolism) in stems in 2006. Additionally, trees grown with CRF had less total shoot biomass in Spring 2006 and more bud failure than trees grown with a similar N rate from UF. Significant relationships between bud failure and N status and C/N ratios in different tissues suggest that a combination of tree N status and the balance between N and C in certain tissues plays a role in the occurrence of bud failure of green ash trees in the spring.

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Carolyn F. Scagel, Richard P. Regan, Rita Hummel and Guihong Bi

A study was conducted to determine whether nitrogen (N) application rate and fertilizer form are related to cold tolerance of buds and stems using container-grown ‘Summit’ green ash (Fraxinus pennsylvanica) trees. Trees were grown with different rates of N from either urea formaldehyde (UF) or a controlled-release fertilizer (CRF) containing ammonium nitrate during the 2006 growing season; and growth, N and carbon (C) composition, and cold tolerance were evaluated in Oct. 2006, Dec. 2006, and Feb. 2007 by assessing the lowest survival temperature (LST) of stem and bud tissues on current season (2006) stems. Both fertilizer type and rate influenced the bud and stem LSTs. The influence of fertilizer rate was most evident on midwinter (December) stem LSTs and the influence of fertilizer type was observed in bud and stem LSTs during the deacclimation period in February. Higher LSTs were associated with higher N concentrations and lower C/N ratios; however, stems and buds of trees fertilized with UF were more cold-tolerant (had lower LSTs) than stems and buds on trees fertilized with CRF. Fertilizer type resulted in several differences in N and C translocation and metabolism during the fall and winter. Our results indicate trees with a similar N status are able to withstand different levels of cold depending on the rate of N and the type or form of fertilizer used during production. This may have to do with differences in how trees metabolize the different fertilizer forms, where and when the N is stored, and how it is remobilized in the spring, especially in relation to C metabolism.

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Mike Caron and Roger Kjelgren

first year water use, 2 years of g S and water potential, and 3 years of total leaf area and shoot elongation of Fraxinus pennsylvanica ‘Patmore’ transplanted as BB and two BR sizes in a high desert climate. Materials and Methods Climate and weather

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Manuela Baietto and A. Dan Wilson

and natural forest stands of temperate forests and the lower Mississippi Delta region: Fraxinus pennsylvanica Marsh., Liquidambar styraciflua L., Platanus occidentalis L., Populus deltoides Bartr. ex Marsh., Quercus lyrata Walt., Quercus

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Amy Jo Waldo and James E. Klett

Ninety trees are being used and have been in the field since 1994. The three species studied include: Fraxinus pennsylvanica Patmore (Green Ash), Quercus macrocarpa (Bur Oak), and Pinus nigra (Austrian Pine); 30 of each species. Each species has been harvested in three different nursery production methods including balled and burlapped, plastic container, and fabric container. During the 1996 growing season, the following data was recorded for each tree, growth increments, caliper size, and tree heights. For the two deciduous species, both dry weights and leaf area were recorded. Some sap flow measurements were taken using a non-intrusive stem heat balance method, on the same tree species with varying production methods. All three species showed the greatest growth increments and heights for those trees planted in fabric containers. In regards to trunk caliper size, Pinus nigra showed that the balled and burlapped, and fabric containers had larger calipers than those planted in plastic containers. Fabric container trees were larger in caliper than plastic container trees, which was larger than the balled and burlapped on Quercus macrocarpa. The plastic container and balled and burlapped resulted in greater calipers on Fraxinus pennsylvanica than the fabric containers. Quercus macrocarpa also showed that both leaf area and dry weight were greatest for trees planted in fabric containers, followed by the other production methods. Trees in plastic containers exhibited the greatest leaf area and dry weight for Fraxinus pennsylvanica. Overall, the fabric container trees in all three species illustrated the highest-quality trees, followed by those planted in plastic containers, and then balled and burlapped. Minimal data was recorded for transpiration rates in 1996 and will be further investigated in 1997.

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Roger Harris, Nina L. Bassuk and Thomas H. Whitlow

Root and shoot phenology were observed, and root length within rootballs were calculated for Fraxinus pennsylvanica Marsh. (green ash), Quecus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish hazelnut), and Syringa reticulata (Blume) Hara `Ivory Silk' (tree lilac) trees established in a rhizotron. Easy-to-transplant species (green ash and tree lilac) had more root length within rootballs than difficult-to-transplant species (Turkish hazelnut and scarlet oak). Shoot growth began before root growth on all species except scarlet oak, which began root and shoot growth simultaneously. Fall root growth ceased for all species just after leaf drop. Implications for tree transplanting are discussed.

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Patricia A. Lindsey and Nina L. Bassuk

The development of a rapid, accurate, yet nondestructive technique for expressing whole-tree leaf area would be extremely useful in studying various growth phenomena in trees. The objective of this research was to evaluate the accuracy of an image analysis process adapted for estimating the leaf surface area of four broad-leafed tree species (Amelanchier L. `Robin Hill Pink', Tilia americana L. `Redmond', Sophora japonica L. `Regent', Fraxinus americana L. `Autumn Purple' and Fraxinus pennsylvanica Marsh.). Video images of photographs taken of each tree canopy were quantified by an image analyzer into unitless surface area values or silhouette areas. The relationship between estimated leaf area as calculated from silhouette area and actual leaf area of these trees as determined by a leaf area meter was highly correlated. Use of this technique would enable a researcher, simply from serial photographs of the canopy, to retroactively estimate leaf or canopy area at crucial interim periods.

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Michael A. Arnold and Eric Young

CuCO3 at 100 g·liter-1 in a paint carrier applied to interior container surfaces effectively prevented root deformation in container-grown Malus domestica Borkh. and Fraxinus pennsylvanica Marsh. seedlings. CuCO3 treatments nearly doubled the number of white unsuberized root tips in both species. CuCO3 treatment increased some measures of root and shoot growth before and after transplanting to larger untreated containers. Root pruning at transplanting tended to reduce root and shoot fresh and dry matter accumulation in F. pennsylvanica seedlings and shoot extension in M. domestica seedlings. In some cases, root pruning of M. domestics at transplanting from CuCO3-treated containers increased root growth compared to unpruned CuCO3-treated and untreated seedlings. Changes in growth induced by CuCO3 and root pruning were not related to changes in trans -zeatin riboside-like activity in the xylem sap of-apple.