The objective of this study was to evaluate the potential use of container substrates composed of whole pine trees. Three species [loblolly pine (Pinus taeda), slash pine (Pinus elliottii) and longleaf pine (Pinus palustris)] of 8–10 year old pine trees were harvested at ground level and the entire tree was chipped with a tree chipper. The chips from each tree species were then further processed with a hammer mill to pass a ½-inch screen. On 29 June 2005 these three substrates along with 100% pinebark were mixed with the addition per cubic yard of 9.49 kg·m–3 Polyon 18–6–12 (18N–2.6P–10K), 2.97 kg·m–3 dolomitic lime and 0.89 kg·m–3 Micromax. One gallon (3.8 L) containers were then filled and placed into full sun under overhead irrigation. Into these containers were planted 72 cell plugs of Catharanthus roseus`Little Blanche'. Data collected were pre-plant chemical and physical properties of substrates, as well as plant growth index (GI), plant top dry weight, root ratings, and plant tissue (leaves) nutrient analysis at 60 days after planting (DAP). The test was repeated on 27 Aug. 2005 with C. roseus Raspberry Red Cooler. Top dry weights were on average 15% greater for the 100% pinebark substrate over all others at 60 DAP. However there were non differences in plant GI for any substrate at 60 DAP. There were no differences in plant tissue macro nutrient content for any substrate. Tissue micronutrient content was similar and within ranges reported by Mills and Jones (1996, Plant Analysis Handbook II) with the exception of Manganese. Manganese was highest for slash and loblolly pine and well over reported ranges. There were no differences in root ratings. There were no differences in substrate physical properties between the three whole tree substrates. However the 100% pinebark substrate had on average 50% less air space and 25% greater water holding capacity than the other substrates. Physical properties of all substrates were within recommended ranges. Based on the results of this study substrates composed of whole pine trees have potential as an alternative sustainable source for a substrate used in producing short term nursery crops.
Glenn B. Fain and Charles H. Gilliam
Patricia R. Knight, D. Joseph Eakes, and Charles H. Gilliam
Two inch caliper Acer rubrum, Quercus phellos, and Platanus occidentalis were planted March 26, 1990, into 8' × 8' planting holes that were lined with either Typar Biobarrier, Dewitt Pro-5 Weed Barrier or left unlined as a control. There has been little or no root penetration beyond the Biobarrier for the 3 tree species during the first 3 years of this study. At the end of 1990, the control and the Dewitt Pro-5 had similar root penetration numbers. By the end of 1991, the Dewitt Pro-5 had greater root penetration than did the control for A. rubrun. Root penetration of Dewitt Pro-5 and the control treatment was similar for Q. phellos and P. occidentalis. There were no differences in root penetration for Dewitt Pro-5 and the control in 1992 for any species. There were no differences in height for any tree species following the 1990 or 1991 growing seasons and no difference following the 1992 growing season for A. rubrum and Q. phellos. The control treatment had the grearest height for P. occidentalis in 1992. There were no differences in caliper due to root control treatment for the 3 species during the first 3 years of this study.
Charles H. Gilliam, Donna C. Fare, and Gary J. Keever
Little information is available on herbicide movement in soilless container media and subsequent movement in container leachate and container bed runoff. The objective of this study was to evaluate oxyfluorfen movement in irrigation water following application to container grown nursery crops in a commercial nursery. Oxyfluorfen levels in the container bed runoff were 9 to 27 times higher than those in container leachate during the 3 irrigations following herbicide application. Maximum oxyfluorfen level in the container leachate was 8.3 ppb following the first irrigation but declined to 2.0 ppb by the 12th irrigation. The oxyfluorfen level was still about 2.0 ppb following the 75th irrigation. Oxyfluorfen in the container bed runoff peaked at 99 ppb following the 3rd irrigation before declining to 67 ppb following the 6th irrigation.
Glenn R. Wehtje, Charles H. Gilliam, and Ben F. Hajek
J. Raymond Kessler, Charles H. Gilliam, and Beth M. Wallace
Little information is available on phytotoxic effects to annual bedding plant species from herbicides commonly used on container-grown woody plant species. Viol×wittrockiana `Crystal Bowl True Blue', `Imperial Antique Shades', and `Maxim Orange' were grown in 2.54-liter (#1) containers using an amended 6 pine bark: 1 sand medium. Five days after containerizing, each cultivar was either hand-weeded or treated with one of 13 granular or spray, pre- or post-emergence herbicides, within recommended rates in two separate studies. Herbicide phytotoxicity ratings were made 15, 30, 60, 90, and 120 d after treatment. Shoot dry weights were taken 120 d after treatment. Most injurious and persistently injurious herbicides were Rout 3G (oxyfluorfen + oryzalin), Pendulum 60 WDG (pendimethalin), and Ronstar 2G (oxadiazon). Low shoot dry weights closely correlated to injury rating. Least injurious herbicides included Pennant 7.8E (metolachlor), Surflan 4AS (oryzalin), Stakeout (dithiopyr), Pennant SG (metolachlor), and Derby SG (metolachlor + simazine). Southern Weedgrass Control, a granular formulation of pendimethalin, was among the least injurious, while Pendulum 60 WDG, a liquid formulation of pendimethalin, was most injurious. Evidence suggests that phytotoxic injury was greater on small, newly transplanted plants, though in some cases they were able to outgrow the injury.
Glenn B. Fain, Charles H. Gilliam, and Gary J. Keever
Hardy ferns are widely grown for use in the landscape. Studies were conducted to evaluate the tolerance of variegated leatherleaf fern (Arachniodes simplicor `Variegata'), tassel fern (Polystichum polyblepharum), autumn fern (Dryopteris erythrosora), holly fern (Cyrtomium falcatum `Rochfordii'), and southern shield fern (Dryopteris ludoviciana), to applications of selected preemergence applied herbicides. Liquid applied herbicides were pendamethalin (LPM) at 3.36 or 6.73 kg·ha–1, prodiamine (LPD) at 1.12 or 2.24 kg·ha–1, isoxaben (LIB) at 1.12 or 2.24 kg·ha–1, and the combination of prodiamine plus isoxaben (LPI) at 1.12 plus 1.12 kg·ha–1. Granular applied herbicides were pendamethalin (GPM) at 3.36 or 6.73 kg·ha–1, prodiamine (GPD)1.12 or 2.24 kg·ha–1, oxadiazon plus prodiamine (GOP) at 1.12 + 0.22 or 2.24 + 0.44 kg·ha–1, oxyfuorfen plus oryzalin (GOO) at 2.24 + 1.12 or 4.48 + 2.24 kg·ha–1, trifluralin plus isoxaben (GTI) at 2.24 + 0.56 or 4.48 + 1.12 kg·ha–1, oxadiazon (GO) at 4.48 or 8.97 kg·ha–1, and oxadiazon plus pendamethalin (GOPD) at 2.24 + 1.4 or 4.48 + 2.8 kg·ha–1. The greatest reduction in growth of autumn fern was observed with GOPD, GO, and GOP; all three containing oxadiazon as an active ingredient. Reductions in holly fern growth were most severe when plants were treated with GTI resulting in a 42% and 54% decrease in frond length and frond number, respectively. There were also reductions in number of fronds when treated with LPM, GPM, GOP, GOO, and GOPD. There were no reductions in frond numbers on tassel fern with any herbicides tested. However, there were reductions in frond length from 6 of the 10 herbicides evaluated. The most sensitive fern to herbicides evaluated in 2004 was leatherleaf with reductions in frond length and number of fronds with 6 of the 10 herbicides tested. While all herbicides tested on southern shield fern appeared to be safe, especially in the 2004 study, tassel fern and holly fern appear to be more sensitive. GPD proved to be a safe herbicide for all species tested in both 2004 and 2005. In 2005 all plants from all treatments were considered marketable by the end of the study. However there was significant visual injury observed on the holly fern treated with LIB at 60 and 90 days after treatment which might reduce their early marketability.
Ken Tilt, Charles H. Gilliam, and John W. Olive
Lagerstroemia × `Natchez' and Quercus virginiana were planted into a sandy loam soil in grow bags and by traditional field planting methods. After 2 years in the field, 1 sample from each of 6 replications was dug from the field in March. Root and top growth were measured. Half the remaining plants were dug and transplanted into 76 liter containers for 3 months. Growth indices were measured at this time. The remaining trees in the field were dug in July and handled similarly. Data from live oak trees showed increased height in trees produced by traditional field planting methods. No differences between planting methods were found in any other growth indices for the two species. Both crapemyrtle and live oak trees transplanted from traditional field plantings in March had greater height than trees transplanted from grow bags. However, no differences were detected for top weight, caliper or root ratings. July transplanted crapemyrtles showed no differences in any of the growth indices. Live oaks transplanted in July from traditional field plantings to containers all died with no additional growth. Grow bag transplanted oaks survived and continued to grow.
Glenn R. Wehtje, Charles H. Gilliam, and Ben F. Hajek
Adsorption of 14C-labeled oxadiazon was evaluated in three soilless media and a mineral soil at concentrations between 0.1 and 100 mg·kg-1. Adsorption, which was at least 96%, was not influenced by absorbent type (medium vs. soil) or by oxadiazon concentration. However, desorption was greater in the media than in the soil. After five water extractions, 5.4% of the applied oxadiazon was recovered from media, but only 0.4% was recovered from the soil. In the soil and in two of the media, leaching with water failed to displace oxadiazon 2 cm below the surface to which it had been applied. No oxadiazon was detected below 4 cm in the third medium. Oxadiazon is sufficiently adsorbed to resist leaching-based displacement. Oxadiazon is not likely to enter the environment by escaping from treated containers. Chemical name used: 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-di-methylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon).
James E. Altland, Charles H. Gilliam, and Glenn Wehtje
Herbicide use is an important component of weed management in field nursery crops. No single herbicide controls all weed species. Oxyfluorfen, simazine, and isoxaben are preemergence herbicides effective against broadleaf weeds. Oryzalin, pendimethalin, and prodiamine are effective in preemergence control of grasses and some small-seeded broadleaf weeds. Metolachlor is the only herbicide currently labeled for nursery crops that is effective in preemergence nutsedge (Cyperus) control. Fluazifop-butyl, sethoxydim, and clethodim are selective postemergence herbicides used for grass control. Glyphosate, paraquat, and glufosinate are nonselective postemergence herbicides used in directed spray applications for broad-spectrum weed control. Bentazon, halosulfuron, and imazaquin are effective postemergence nutsedge herbicides. These herbicides are discussed with respect to their chemical class, mode of action, labeled rates, and current research addressing their effectiveness in nursery crops.
Donna C. Fare, Charles H. Gilliam, and Gary J. Keever
Efficient usage of current water supplies is of great concern to container-nursery producers. Improving water management first requires knowledge of current commercial container production practices. In this study, irrigation distribution from overhead sprinklers was monitored at container nurseries to determine the distribution and the amount of irrigation applied during a typical irrigation cycle. Several nurseries surveyed had poorly designed irrigation systems; subsequently, irrigation distribution varied widely at sampling dates and within the growing-container block. Uniform distribution was achieved at some nurseries, but required careful monitoring of the irrigation system. Future water restrictions may force nurseries to improve water usage by changing irrigation delivery methods to minimize water use, resulting in reduced surface runoff and effluent from container nurseries.