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Alexander X. Niemiera

Amending soilless media with micronutrients is a routine nursery practice. The objective of this research was to determine the micronutrient status of pine bark amended with two sulfate micronutrient sources and a control (unmended). Limed pine bark was unamended, amended with Ironite (1 and 2 g/l), or Micromax (1g/l). Bark was irrigated with distilled water in amounts equivalent to 30, 60, 90, and 120 irrigations (.63 cm per irrigation). Following irrigations, Cu, Fe, Mn, and Zn were extracted with a modified saturated media extract method using .001M DPTA as the extractant. Irrigation amount had no effect on Cu and Mn concentrations which were greater in the Micromax treatment than the Ironite or control treatments. A micronutrient source × irrigation interaction existed for Fe and Zn concentrations requiring regression analysis. In general, slope values indicating the decrease in micronutrient values with increasing irrigations were quite low (≤ .001) for each source. Regardless of irrigation amount, Fe and Zn concentrations were similar for amended and unamended bark.

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Jeffrey G. Williamson and E. Paul Miller

Bearing `Misty' and `Star' southern highbush blueberries were grown on pine bark beds and fertilized at three rates using granular and liquid fertilizers with a 3–1–2 (1N–0.83K–0.88P) ratio. Granular fertilizer was applied 8 times per year at 4-week intervals beginning in April and continuing through October. Liquid fertilizer was applied with low volume irrigation 16 times per year at 2-week intervals during the same period. During the growing season, irrigation was applied at 2- to 3-day intervals in the absence of rain. A 2 cultivar × 2 fertilizer type × 3 fertilizer rate factorial arrangement of treatments was replicated 8 times in a randomized complete-block design. All fruits were harvested from single-plant plots at 3- to 4-day intervals. Canopy volume was not affected by fertilizer type, but fruit yield was slightly greater for granular than for liquid fertilizer treatments. In 2003, fruit yield of 2.5-year-old `Misty' and `Star' plants increased with increasing fertilizer rates up to the highest rate tested (50 g N/plant/year). Similarly, in 2004, fruit yields increased with increasing fertilizer rates up to the highest rate (81 g N/plant/year). Root distribution was limited to the 12-cm-deep layer of pine bark with very few roots penetrating into the underlying soil. The positive growth responses of blueberry plants to high fertilizer rates in pine bark beds suggests that soluble fertilizer was leached through the pine bark layer into the soil below the root zone. More frequent, lighter applications of soluble fertilizers, use of slow-release or controlled-release fertilizers, and careful irrigation management may improve fertilizer use efficiency of blueberry plantings on pine bark beds.

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Hannah M. Mathers and Michele M. Bigger

Many nurseries within Ohio and northeastern, southeastern, and western United States, and Canada have reported severe bark splitting and scald-type problems in 2005. The amount and severity of damage seen in 2005 has been unlike anything seen before. At Ohio State University, samples from across the state started appearing in 2003–04 and increased in incidence in 2005. Growers' reports of exceeding losses of 5% of their inventory or 3000 to 4000 trees per nursery are not uncommon. At an average cost of $125 per tree and with the number of nurseries reporting problems, the stock losses in Ohio have been staggering, in excess of several million dollars. The trees that we have seen problems on in 2005 have been callery pears, yoshino cherry, kwanzan cherry, crab apples, sycamore, serviceberry, hawthorn, mountain ash, black gum, paper bark maple, japanese maples, norway maple `Emerald Queen', red maples, kousa dogwood, magnolia `Elizabeth' and the yellow magnolias such as `Butterflies', `Sawada's Cream', `Yellow Bird', and `Yellow Lantern'. It has long been observed that the actual cause of a bark crack was “preset” by a wound such as the improper removal of a basal sprout, herbicide, leaving of a branch stub, or lack of cold hardiness. Cold and frost may be contributing to the increase in bark splitting across the United States; however, new research results at Ohio State University regarding the effects of DNA preemergent herbicides in the reduction of root hardiness and regrowth potential, sprout removal and other mechanical injuries, and postemergent herbicide application will reveal these are more the causal agents.

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John M. Englert, Gary D. Coleman, Tony H.H. Chen, and Leslie H. Fuchigami

A 32kDa bark storage protein (BSP) which accumulates in the fall and is degraded in the spring has been identified in Populus deltoides bark. The BSP gene has been shown to be regulated by short day (SD) photoperiod (8 h). The physiological condition of the plant and the environmental factors necessary for the degradation and retranslocation of BSP are of considerable interest for determining the role of this protein in the remobilization of nitrogen in trees.

Poplar plants were placed in a SD growth chamber for 4 or 7 weeks to induce growth cessation (bud set) or dormancy, respectively. BSP accumulated to high levels in bark tissues after 3 weeks SD and remained high through 7 weeks SD. Plants in which growth had stopped (4 weeks SD), or in which dormancy (7 weeks SD) was broken with hydrogen cyanamide (0.5 M) or chilling (4 weeks 0C) broke bud within 1 week of being placed into long day (LD) conditions. Dormant plants which were not chilled broke bud after 3 weeks LD. BSP levels decreased around the time of budbreak, suggesting that the degradation of BSP is dependent on the need for a nitrogen sink, ie. budbreak and new shoot growth.

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Thomas Yeager, Ed Gilman, Diane Weigle, and Claudia Larsen

Columns (4 × 15 cm) of a pine bark medium amended with the equivalent of 4.2 kg per cubic meter of dolomitic limestone and either 0, 2.4, 4.7, 7.1 or 9.5 mg of urea-formaldehyde (38% N) per cubic centimeter of medium were leached daily with 16 ml of deionized water (pH 5.5). Leachate total N, NO3 --N and NH4 +-N concentrations were determined on day 1, 3, 5, 7, 14, 28, 49, 91, 133, 203, 273 and 343. Leachate total N ranged from 600 ppm on day 1 for the 9.5 mg treatment to 4 ppm on day 273 for the 2.4 mg treatment. Leachate NH4 +-N concentrations ranged from 38 ppm c4 day 3 for the 9.5 mg treatment to less than 1 ppm on day 7 for the 2.4 mg treatment and were less than total N concentrations at each sampling time. Leachate NO3 --N was not detectable during the experimental period. Eleven, 16, 20 and 25% of the applied N leached from the columns amended with 2.4, 4.7, 7.1 or 9.5 mg of urea-formaldehyde per cubic centimeter of pine bark, respectively, during the 371 day experiment.

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John D. Lea-Cox and Irwin E. Smith

Pine bark is utilized as a substrate in citrus nurseries in South Africa. The Nitrogen (N) content of pine bark is inherently low, and due to the volubility of N, must be supplied on a continual basis to ensure optimum growth rates of young citrus nursery stock. Three citrus rootstock (rough lemon, carrizo citrange and cleopatra mandarin) showed no difference in stem diameter or total dry mass (TDM) when supplied N at concentrations between 25 and 200 mg ·l-1 N in the nutrient solution over a 12 month growing period. Free leaf arginine increased when N was supplied at 400 mg·l-1 N. The form of N affected the growth of rough lemon. High NH4-N:NO3-N (75:25) ratios decreased TDM when Sulfur (S) was absent from the nutrient solution, but not if S was present. Free arginine increased in leaves at high NH4-N (No S) ratios, but not at high NH4-N (S supplied) ratios. Free leaf arginine was correlated with free leaf ammonia. These results have important implications for reducing the concentration of N in nutrient solutions used in citrus nurseries and may indicate that higher NH4-N ratios can be used when adequate S is also supplied.

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Alex X. Niemiera, Ted E. Bilderback, and Carol E. Leda

Pine bark (PB), either unamended or amended with sand (S) at 9 PB: 1 S or 5 PB:1 S (v/v), was fertilized with solutions of 100,200, or 300 mg N/liter solution and tested for N concentration using the pour-through method (PT). PB, 9 PB: 1 S, and 5 PB: 1 S had porosities of 84%, 75%, and 66%, respectively. PT NO3-N concentrations, obtained via PT, of the 5 PB:1 S substrate were 43%,28%, and 15% higher than PB NO3-N values for the 100,200, and 300 mg·liter-1 treatments, respectively. Differences in N concentration obtained with PT can be attributed to substrate physical characteristics. Based on the results, data for PT should be interpreted with regard to substrate porosity.

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M. Pilar Bañados, Gary D. Coleman, and Tony H. H. Chen

In poplar (Populus deltoides) a 32kDa bark storage protein (BSP) accumulates during the fall, and is a major form of stored nitrogen during overwintering. This protein is induced by short-day (SD) photoperiod and may play an important role in nitrogen cycling in the plant. To determine the effect of plant nitrogen status upon BSP gene expression, poplar plants were grown in controlled environmental chambers under either SD or long-day (LD) photoperiods and watered with either 5, 10, 50, and 100 mM NH4NO3 for four weeks. [15N]-NH4NO3 was applied during the first and third weeks. SDS-PAGE and western blot analysis were used to detect the relative amounts of BSP. RNA gel blot analysis was used to determine the changes in BSP gene expression. BSP accumulation was enhanced by increasing levels of nitrogen under both photoperiods, however, SD photoperiod appears to moderate the response. These results indicate that BSP gene expression is dependant upon the nutritional status of the plant. [15N] analysis will also be presented.

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Celina Gómez and James Robbins

The most common components of soilless container media used by the nursery industry in the United States are bark from loblolly pine ( Pinus taeda L.) and douglas fir [ Pseudotsuga menziesii (Mirb.) Franco]. Loblolly PB is widely used by growers

Open access

J. E. Klett, J. B. Gartner, and T. D. Hughes


Hardwood bark was used in combination with other materials as media for forsythia and juniper plants in containers with various growing procedures, bark sources, and fertility practices. Based on dry wt, the most rapid growth of forsythia was obtained in a bark and fine sand medium; whereas, the least growth was obtained in soil, peat, and perlite. However, pfitzer juniper plants under 2 different fertility regimes grew most rapidly in a bark, soil, and peat medium, slowest in a bark and torpedo #2 sand medium, and at an intermediate growth rate in soil, peat, and perlite. The standard mix (soil, peat, and perlite) was more acidic than the experimental mixes containing bark and sand. Chlorotic plants were more numerous in acidic mixes. Leaf tissue analyses from the plants grown in the peat amended bark and standard mix had higher Fe and Mn concn than plants grown in a bark-sand mix.