A substrate component (WholeTree) made from loblolly pine (Pinus taeda L.) was evaluated along with starter fertilizer rate in the production of greenhouse-grown petunia (Petunia ×hybrida Vilm. ‘Dreams Purple’) and marigold (Tagetes patula L. ‘Hero Spry’). Loblolly pine from a 12-year-old plantation were harvested at ground level, chipped, and further processed through a hammer mill to pass a 0.64-cm screen. The resulting WholeTree (WT) substrate was used alone or combined with 20% (WTP2) or 50% (WTP5) (by volume) Canadian sphagnum peatmoss and compared with an industry standard peat-lite (PL) mix of 8 peatmoss : 1 vermiculite : 1 perlite (by volume). Substrates were amended with 1.78 kg·m−3 dolomitic lime, 0.59 kg·m−3 gypsum [CaSO4-2(H2O)], 0.44 kg·m−3 Micromax, 1.78 kg·m−3 16N–2.6P–9.9K (3- to 4-month release), and 1.78 kg·m−3 16N–2.6P–10.8K (5- to 6-month release). A 7N–1.3P–8.3K starter fertilizer (SF) was added to each substrate at 0.0, 1.19, 2.37, or 3.56 kg·m−3. Container capacity (CC) was greatest for PL and decreased as the percentage of peatmoss in the substrate decreased with WT having 35% less CC than PL. Conversely, air space (AS) was greatest for the WT and decreased as percentage of peatmoss increased with PL containing 33% less AS than WT. In general, petunia dry weight was greatest for any substrate containing peatmoss with a SF rate of 2.37 kg·m−3 or greater. The exception was that petunia grown in WT at 3.56 kg·m−3 SF had similar dry weight as all other treatments. Marigold dry weight was similar for all substrates where at least 2.37 kg·m−3 SF was used.

The objective of this study was to evaluate the potential for use of container substrates composed of processed whole pine trees (WholeTree). Three species [loblolly pine (Pinus taeda), slash pine (Pinus elliottii), and longleaf pine (Pinus palustris)] of 8- to 10-year-old pine trees were harvested at ground level and the entire tree was chipped with a tree chipper. Chips from each tree species were processed with a hammer mill to pass through a 0.374-inch screen. On 29 June 2005 1-gal containers were filled with substrates, placed into full sun under overhead irrigation, and planted with a single liner (63.4 cm3) of ‘Little Blanche’ annual vinca (Catharanthus roseus). The test was repeated on 27 Aug. 2005 with ‘Raspberry Red Cooler’ annual vinca. Pine bark substrate had about 50% less air space and 32% greater water holding capacity than the other substrates. At 54 days after potting (DAP), shoot dry weights were 15% greater for plants grown in 100% pine bark substrate compared with plants grown in the three WholeTree substrates. However, there were no differences in plant growth indices for any substrate at 54 DAP. Plant tissue macronutrient content was similar among all substrates. Tissue micronutrient content was similar and within sufficiency ranges with the exception of manganese. Manganese was highest for substrates made from slash pine and loblolly pine. Root growth was similar among all treatments. Results from the second study were similar. Based on these results, WholeTree substrates derived from loblolly pine, slash pine, or longleaf pine have potential as an alternative, sustainable source for producing short-term horticultural crops.

The market for large plants is increasing steadily; however, weed control in large containers present new production problems for growers. Experiments were conducted to evaluate pine bark mini-nuggets for weed control in 11 and 27 liter (#3 and #7) containers. In October 2004, Gardenia jasminoides (August Beauty gardenia) were seeded with oxalis, and Lagerstroemia indica ‘Natchez’ (crapemyrtle) with bittercress in 27 liter (#7) containers. In March 2005, Hydrangea quercifolia (oakleaf hydrangea) were seeded with oxalis and Ternstroemia gymnanthera (ternstroemia) with bittercress in 11 liter (#3) containers. Treatments consisted of mulch applied at depths of 0, 3.8, and 7.6 cm (0, 1.5 and 3.0 in), with seed applied either above or below the mulch. A separate group of treatments were included similar to the above except that a granular preemergence herbicide was applied after mulch application. Growth of crapemyrtle and ternstroemia were similar regardless of mulch depth. With gardenia and oakleaf hydrangea growth differences existed but there were no consistent trends among treatments. Season long weed control was obtained in all treatments that included 7.6 cm (3.0 in) mulch depth.

Increased trace gas emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are widely believed to be a primary cause of global warming. Agriculture is a large contributor to these emissions; however, its role in climate change is unique in that it can act as a source of trace gas emissions or it can act as a major sink. Furthermore, agriculture can significantly reduce emissions through changes in production management practices. Much of the research on agriculture’s role in mitigation of greenhouse gas (GHG) emissions has been conducted in row crops and pastures as well as forestry and animal production systems with little focus on contributions from specialty crop industries such as horticulture. Our objective was to determine efflux patterns of CO2, CH4, and N2O associated with three different fertilization methods (dibble, incorporated, and topdressed) commonly used in nursery container production. Weekly measurements indicated that CO2 fluxes were slightly lower when fertilizer was dibbled compared with the other two methods. Nitrous oxide fluxes were consistently highest when fertilizer was incorporated. Methane flux was generally low with few differences among treatments. Results from this study begin to provide data that can be used to implement mitigation strategies in container plant production, which will help growers adapt to possible emission regulations and benefit from future GHG mitigation or offset programs.

Using results of a socioeconomic survey of nurseries and greenhouses, Tobit regression analysis was used to estimate empirical models to measure the socioeconomic impact of automation or mechanization on annual gross sales, annual employment, and workers' earnings, safety, and retention. The survey was conducted among 87 randomly selected nurseries and greenhouses located in Mississippi, Louisiana, and Alabama, from Dec. 2003 to Mar. 2005. About 20% of all the identified major tasks were performed by workers in nurseries and greenhouses with some form of mechanization or automation. Regression results showed that nurseries and greenhouses that experienced higher levels of sales also demonstrated higher levels of automation or mechanization. The employment impact of automation or mechanization was neutral, indicating that any improvement in automation or mechanization did not necessarily lead to a reduction, but instead to a more efficient use of labor by nurseries and greenhouses. Improvements in automation or mechanization resulted in higher total workers' earnings reported by participating nurseries and greenhouses. Further Tobit regression results showed that automation or mechanization had neutral effects on the length of training period, workers' safety, and retention rates and enabled nurseries and greenhouses to hire less-skilled workers.