al., 2006 ; Fain et al., 2006 ; Laiche and Nash, 1986 ; Wright and Browder, 2005 ). Although pine bark (PB) is a product/component of pine trees, for the purpose of describing pine wood-based substrates that have recently been investigated, it is
Brian E. Jackson, Robert D. Wright, and Michael C. Barnes
Jeb S. Fields, James S. Owen Jr., and Holly L. Scoggins
experimental pine bark-based substrates used to produce Hydrangea arborescens plants. Substrates included conventional pine bark (unprocessed bark, UB), bark particles that pass through a 4.0-mm screen (fine bark, FB), bark particles that do not pass through
Jeb S. Fields, William C. Fonteno, and Brian E. Jackson
(OM) components in them. These components, primarily composed of sphagnum peatmoss and pine bark, can become hydrophobic, thus reducing wettability ( Dekker et al., 2000a ; Michel et al., 2001 ). The molecules of OM contain many organic acid
Research reports documenting phosphorus leaching from soilless container media has changed commercial nursery phosphorus fertilizing practices. However, rhododendron growers are concerned that phosphorus levels are adequate as plants begin setting flower buds in July and August. Medium solution of 10 to 15 ppm P are recommended. Five replicated leachate samples were collected from 6 phosphate sources for 11 weeks following surface application to 2 container grown rhododendron cultivars. Each fertilizer source wax blended to an analysis of 14.0N-11.2P-5.0K except a 14.0N-0P-5.0K control. Phosphate sources included Diammonium Phosphate, Triple superphosphate, Sulfur coated Diammonium Phosphate, Sulfur coated triple superphosphate, and a commercial rhododendron sulfur coated fertilizer. With the exception of control, all treatment leachate phosphorus levels ranged from 180 to 145 ppm two days and 85 to 75 ppm one week after application. All sources ranged from 45 to 10 ppm weeks 2-5 and were lower than 10 ppm weeks 7-11. Leachate levels of the control were below 10 ppm at all sample times. Bud set and foliar P levels were different among phosphate treatments, but growth index measurements were not significant.
Janet C. Cole and John M. Dole
These studies were conducted to determine the effect of 1) temperature on P leaching from a soilless medium amended with various P fertilizers, 2) water application volume on P leaching, and 3) various fertilizers on P leaching during production and growth of marigolds (Tagetes erecta L. `Hero Flame'). Increasing temperature linearly decreased leaching fraction; however, total P leached from the single (SSP) or triple (TSP) superphosphate-amended medium did not differ regardless of temperature. Despite a smaller leaching fraction at higher temperatures and no change in the total P leached, P was probably leached more readily at higher temperatures. More P was leached from the medium amended with uncoated monoammonium phosphate (UCP) than from the medium containing polymer-coated monoammonium phosphate (CTP) at all temperatures, and more P was leached from UCP-amended medium at lower temperatures than at higher temperatures. More P was leached from TSP- than from SSP-amended medium and from UCP- than from CTP-amended medium regardless of the water volume applied, but leachate P content increased linearly as water application volume increased for all fertilizers tested. Plant dry weights did not differ regardless of P source. Leachate electrical conductivity (EC) was lower with TSP than with SSP. Leachate EC was also lower with CTP than with UCP. A higher percentage of P from controlled release fertilizer was taken up by plants rather than being leached from the medium compared to P from uncoated fertilizers.
Cheryl R. Boyer, Glenn B. Fain, Charles H. Gilliam, Thomas V. Gallagher, H. Allen Torbert, and Jeff L. Sibley
these large containers are composed primarily of aged pine bark and Canadian sphagnum peatmoss blends. These materials provide support for plant growth structurally as well as providing a nutrient and water reservoir. Pine bark (PB) and peatmoss (PM) are
B.H. Ownley, D.M. Benson, and T. E. Bilderback
One-year-old Rhododendron L. `Nova Zembla' were grown in four container media infested with Phytophthora cinnamomi Rands. The media (all v/v) were pine bark, 3 pine bark:1 sand, 3 pine bark:1 peat, and 1 peat: 1 sand: 1 soil. After 20 weeks, plants were evaluated for root rot symptoms and the total porosity, air space, moisture-holding capacity, and bulk density were determined for all media. All media provided adequate moisture-holding capacity for container production of rhododendron in noninfested media. Shoot fresh weight in noninfested media was positively correlated with bulk density and water (percent by volume) held in the 1.0- to 5.0-kPa matric tension range and negatively correlated with total porosity and air space. Root rot severity was greatest in peat: sand: soil, intermediate in pine bark: peat, and least in pine bark and pine bark: sand. Root rot severity was negatively correlated with total porosity and air space and positively correlated with bulk density and water (percent by volume) held in the 5.0- to 10.0-kPa matric tension range.
Robert D. Wright and Jake F. Browder
Due to uncertainties of future supplies of pine bark (PB) and peatmoss, ground Pinus taeda logs [pine chips (PC)] were compared to ground PB as a potential container substrate for japanese holly (Ilex crenata Thunb. `Chesapeake'), azalea (Rhododendron obtusum Planch. `Karen'), and marigold (Tagetes erecta Big. `Inca Gold'). Plants were potted in 2.8-L plastic containers 8 Apr. 2004 with either 100% PC, 100% PB, or 75% PC:25%PB (v/v), and glasshouse grown 8 weeks for marigold and 13 weeks for holly and azalea. Plant dry weights were higher for marigold grown in 100% PB compared to 100% PC but not different from plants grown in 75% PC:25% PB. Plant dry weights of azalea were higher in 100% pine bark than both substrates containing chips. There was no difference in shoot dry weight for japanese holly between the three substrates. Root dry weight was higher for 75% PC:25% PB than for 100% PB, but root weight of 100% PB and 100% PC was the same. The percent air space for the PC was higher than the PB substrate but container capacity and available water was not different for the three substrates. Substrate solution electrical conductivity (EC) for PC, was lower than that of PB, possibly due to greater leaching with the more porous PC and nutrient retention by the PC. These factors could account for the cases where larger plants developed with the PB substrate. Nutrient analysis of the substrate solution indicated that there are no toxic nutrient levels associated with PC. The pH of PC is also acceptable for plant culture. As well, there was no apparent shrinkage due to decomposition during the course of this short-term experiment. Pine chips, therefore, offer potential as a container substrate for greenhouse and nursery crops.
Jeanine M. Davis
Using various mulches for small-scale, commercial basil (Ocimum basilicum L.) production was examined. Sweet basil and bush basil, on raised beds with drip irrigation, were grown on bare ground or mulched with black polyethylene, wheat straw, hardwood bark, or mixed wood chips. Bacterial soft rot (Erwinia spp.) was highest for both basils grown with wheat straw and for sweet basil grown on bare ground or with back polyethylene mulch. Both basils grown with hardwood and pine bark mulches had few soft ret symptoms. All mulches provided acceptable weed control. Yields throughout the growing season were highest with black polyethylene mulch and lowest with hardwood and pine bark mulches.
Mark A. Nash and Franklin A. Pokorny
Component and particle-size effects on shrinkage of two-component potting media were determined. Milled pine bark-sand mixtures were used to determine particle-size effects on shrinkage. Shrinkage curves formed an inverted V with maximum shrinkage at the 1:1 (v/v) ratio. No shrinkage occurred when bark was mixed with bark or sand with sand. Shrinkage increased linearly in the range of 0% to 50% bark and decreased linearly in the range of 50% to 100% bark. Each half of the shrinkage curve was a mirror image of the other half. Shrinkage curves for peat-sand and peat-perlite were similar in form to that of bark-sand media.