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Four deciduous ornamental shrubs [`Coral Beauty' cotoneaster (Cotoneaster dammeri C.K. Schneid); Tartarian dogwood (Cornus alba L.); `Lynwood' forsythia (Forsythia × intermedia Zab.); `Variegata' weigela (Weigela florida Bunge A.D.C.)] were grown in trickle-fertigated containers. There were eight media consisting of 25% or 50% sphagnum peat or composted pine bark, 25% sand, and the remainder one of two sources of spent mushroom compost; four media with 509″ peat or bark mixed with 50% spent mushroom compost; and a control medium of 10070 pine bark. Initially, higher than desirable salt levels in all compost-amended media were leached quickly (within 2 weeks of planting) and not detrimental to the species tested. Unlike cotoneaster, which showed no difference in growth (shoot dry weight) due to medium, dogwood, forsythia, and weigela grew significantly better in all compost-amended media than in the control. Growth of these three species was 20% greater in peat-based than in bark-based, compost-amended media. Dogwood and forsythia grew slightly more (+8%) with spent mushroom compost based primarily on straw-bedded horse manure than with one based on a blend of straw-bedded horse manure, wheat straw, and hay. The addition of sand (25%) to a mixture of 50% peat or bark and 25 % spent compost produced a medium with minimal compaction.

The pour-through (PT) nutrient extraction method involves collection of leachate at the container bottom that results from displacement of substrate solution by water applied to the substrate surface. The PT is a convenient and effective means of monitoring the nutritional status of the soilless container substrates used in the nursery industry, but is less convenient for large containers, particularly those used in the “pot-in-pot” system of growing trees in production containers within in-ground socket containers. We describe a simple vacuum method of extracting solution from pine bark in containers using ceramic cup samplers. When N was applied to a pine bark substrate at 56–280 mg/L, extractable N was slightly higher for the PT than for the ceramic cup method. The correlation between applied and extractable N was 0.99 for both methods. Further comparison of pine bark extract nutrient and pH levels for PT and ceramic cup methods will be presented.

Abstract

Potassium concentration was highest in the upper 5 cm of medium after leaching with 10 cm H₂O, lowest in the middle of the soil column (10 and 15 cm depths), and intermediate at the bottom of the column. Increasing concentrations of applied K (336, 671, and 1007 kg/ha) increased the K level in each medium tested, except 100% sand, and at each depth in the soil column. After leaching, media containing high percentages of sand (75 and 100%) had a lower K concentration at all applied K rates than media containing high percentages of bark (0 and 25% sand). Cation exchange capacity was greater in bark than sand and is probably the most important factor influencing the movement of K in pine bark and sand media.

Abstract

Rooted cuttings of Ilex crenata Thunb. ‘Helleri’, Rhododendron obtusum Planch. ‘Rosebud’, and Juniperus chinensis L. ‘San Jose’ were grown in a 100% pine-bark medium amended with dolomitic limestone at 0 to 8 kg m^-3 with resulting pH from 3.4 to 7.2. Except for juniper at 2 kg m^-3, growth was not increased by liming, and 8 kg m^-3 tended to reduce shoot and root growth. This reduced growth was attributed in part to greater NH₄ adsorption by the bark, reducing the amount available for plant uptake, and a higher nitrification rate, leading to an elevated NO₃ to NH₄ ratio in the medium. Liming pine bark to improve growth of these woody plants may be unnecessary.

Vegetatively propagated plants (15-cm in leaf spread) of a white-flowered Phalaenopsis Taisuco Kaaladian clone were imported bare-root in late May and planted in a mix consisting of three parts of medium-grade fir bark and one part each of perlite and coarse Canadian peat (by volume) or in Chilean sphagnum moss. All plants were given 200 mg·L^-1 each of N and P, 100 mg·L^-1 Ca, and 50 mg·L^-1 Mg. K concentrations were 0, 50, 100, 200, 300, 400, and 500 mg·L^-1. After 7 months, plants grown in moss produced an average of two more leaves than those in the bark mix (4 to 5 vs. 2 to 3 leaves), regardless of K rates. In any given medium, K rate did not alter the rate of leaf production. The K rate did not affect the size of the top leaves when grown in the bark mix. However, plants grown in moss had increasingly longer and wider top leaves as K rate increased. The lower leaves on plants in the bark mix receiving no K showed deficiency symptoms of purple tinting, yellowing, necrosis, and even death. Yellowing and necrosis started from the leaf tip and progressed basipetally. The K at 50 mg·L^-1 reduced and 100 mg·L^-1 completely alleviated the symptoms of K deficiency. Plants grown in moss and receiving no K showed limited signs of K deficiency. Flowering stems started to emerge (spiking) from plants in the bark mix up to 4 weeks earlier than those planted in sphagnum moss. For plants receiving no K, all plants in the bark mix bloomed, whereas none planted in sphagnum moss produced flowering stems. Overall, at least 200 mg·L^-1 K (∼250 mg·L^-1 K₂O) is recommended to produce quality plants with maximum leaf growth and early spiking.

Abstract

A standard 1:1 v/v pine bark and sand potting medium was characterized physically by particle size distribution, bulk density (BD), total pore space, porosity at 50 cm H₂O tension and porosity at >50 cm H₂O tension. A potting medium identical to the standard was constructed from component milled pine bark and sand particles. Phaseolus lunatus L. ‘Jackson Wonder’ plants grown in the 2 physically similar media, under a standard cultural program, were essentially identical. Construction of a potting medium from a prescribed screen analysis provides a means to quantify variation which exists within a medium assumed to be uniform.

Terminal stem cuttings of seven woody nursery species [boxwood (Buxus sempervirens L. `Green Mountain'), coralberry (Symphoricarpus × chenaultii Rehd. `Hancock'), lilac (Syringa velutina Kom.), Peegee hydrangea (Hydrangea paniculata Siebold. `Grandiflora'), purple-leaf sandcherry (Prunus × cistena N.E. Hansen), Rose-of-Sharon (Hibiscus syriacus L. `Lucy'), and winged spindle-tree (Euonymus alata Thunb.) Siebold. `Compacta')] were rooted under outdoor lath (50% shade) and mist in leached rooting media consisting of 0, 20, 40, 60 and 80% by volume of 2-year-old grape pomace amended in binary mixtures with sphagnum peat, perlite or composted bark. Rooting performance, expressed in terms of percent rooting, mean root number per rooted cutting, and length of the longest root per cutting, was regressed on level of pomace. When there were differences due to amendments, most species rooted better with perlite than with bark and peat, to a lesser degree, due in part to more favourable air-filled porosities with perlite (33% to 42%) than with bark (29% to 37%) or peat (24% to 35%). With boxwood, increasing level of pomace up to ≈60%, especially when mixed with perlite or peat, resulted in substantial increases in rooting percentage, root number and length. All three rooting parameters of winged spindle-tree decreased linearly with increasing level of pomace with perlite or bark. The effect of pomace level on other species varied between these extremes with little or no negative effect on rooting.

Bifenthrin and fipronil are important pesticides used in the nursery industry for the control of imported fire ants. Our research measured the influence of irrigation frequency and time on the degradation of bifenthrin and fipronil in pine bark nursery medium. Pine bark media leachates were collected over a 180-d period. Levels of bifenthrin, fipronil, and metabolites of fipronil (MB 46513, MB 45950, MB 46136) were measured using gas chromatography and mass spectrophotometery. Bifenthrin leachate concentrations decreased from 60 ppb on day 1 to ≈1 ppb after 120 d. Fipronil leachate concentrations decreased from 40 ppb on day one to a low of 15 ppb after 120 d. In contrast, metabolites MB 45950 and MB 46136 gradually increased over the 180-d period. Metabolite MB 46513 was not detected during the experiment. Pine bark medium leachate concentrations of bifenthrin and fipronil were greater than previously reported levels in pure water. We theorize that organic compounds present in pine bark may have increased the solubility of these chemicals.

Beit Alpha cucumber (Cucumis sativus) is an exciting new greenhouse crop for production in the southeastern U.S. and Florida. Beit Alpha cucumbers are short, seedless fruit with dark-green skin and an excellent sweet flavor. Beit Alpha-types are the leading cucumber types in the Middle Eastern market and have gained recent popularity in Europe. Beit Alpha cucumbers grown hydroponically under a protected structure have prolific fruit set, yielding more than 60 high-quality fruit per plant during one season. U.S. hydroponic vegetable production is generally associated with structure and irrigation investments which are costly as well as other inputs, such as the media, which must be replaced annually or with each crop. Beit Alpha cucumber `Alexander' was grown in Spring 2001 and 2002 in a passive-ventilated high-roof greenhouse in Gainesville, Fla. Three media types, coarse-grade perlite, medium-grade perlite, and pine bark, were compared for efficiency of growing cucumbers (production and potential costs). During both seasons, fruit yield was the same among media treatments [average of 6 kg (13.2 lb) per plant]. Irrigation requirements were the same for each type of media; however, leachate volume was sometimes greater from pots with pine bark compared to either grade of perlite suggesting a reduced need for irrigation volume when using pine bark. Pine bark is five times less expensive than perlite and was a suitable replacement for perlite in a hydroponic Beit Alpha cucumber production system.

Abstract

Greenhouse-grown branched liners of ‘Helleri’ holly were fertilized with either 0, 5, 10, 15, 20, 25, or 30 ppm P to establish a P level in the pine bark medium that resulted in maximum shoot dry weight. Pine bark P levels greater than 10 ppm did not result in increased shoot dry weight. Total mg of P in shoot tissues continued to increase with P treatments higher than 10 ppm, indicating luxury consumption of P. Total mg of P in root tissues increased to the 5 ppm P treatment. Total μg of Mn in shoot tissues increased while total pg of Mn in root tissues decreased with increasing pine bark P levels. In a subsequent experiment, dry shoot weights of ‘Helleri’ holly grown in a pine bark medium amended with either 270, 540, or 810 g/m³ of P supplied as superphosphate (9% P) or fertilized with 10 ppm P were not different, while root dry weights decreased with increasing P amendment. Water extractable P for the 810 g/m³ treatment decreased 245 ppm during the experiment and by week 5 was below 10 ppm.