Search Results

You are looking at 11 - 20 of 57 items for

  • Author or Editor: Charles H. Gilliam x
Clear All Modify Search

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.

Free access

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).

Free access

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.

Free access

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.

Free access

Experiments were conducted in Auburn, AL, and Aurora, OR, to evaluate herbicides for pre-emergence liverwort (Marchantia polymorpha) control. Granular pre-emergence herbicide efficacy varied by location and product. Summarizing across all experiments, flumioxazin and oxadiazon provided the most effective control in Alabama, whereas flumioxazin and oxyfluorfen + oryzalin provided the most effective control in Oregon. Sprayed quinoclamine provided pre-emergence liverwort control, but efficacy and duration of control were reduced compared with granular herbicides.

Full access

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.

Free access

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.

Full access

Hardy ferns are widely grown for use in the landscape. The 1998 National Agricultural Statistics Services census of horticulture reported production of hardy/garden ferns at 3,107,000 containers from over 1200 nurseries. There is little research on herbicide use in hardy ferns, and herbicides that are labeled for container production are not labeled for use on hardy ferns. Studies were conducted to evaluate the tolerance of variegated east indian holly fern (Arachniodes simplicior `Variegata'), tassel fern (Polystichum polyblepharum), autumn fern (Dryopteris erythrosora), rochford's japanese holly fern (Cyrtomium falcatum `Rochfordianum'), and southern wood fern (Dryopteris ludoviciana), to applications of selected preemergence applied herbicides. Herbicides evaluated included selected granular or liquid applied preemergence herbicides. Spray-applied herbicides were pendimethalin at 3.0 or 6.0 lb/acre, prodiamine at 1.0 or 2.0 lb/acre, isoxaben at 1.0 or 2.0 lb/acre, and prodiamine + isoxaben at 1.0 + 1.0 lb/acre. Granular-applied herbicides were pendimethalin at 3.0 or 6.0 lb/acre, prodiamine at 1.0 or 2.0 lb/acre, oxadiazon + prodiamine at 1.0 + 0.2 or 2.0 + 0.4 lb/acre, oxyfluorfen + oryzalin at 2.0 + 1.0 or 4.0 + 2.0 lb/acre, trifluralin + isoxaben at 2.0 + 0.5 or 4.0 + 1.0 lb/acre, oxadiazon at 4.0 or 8.0 lb/acre, and oxadiazon + pendimethalin at 2.0 + 1.25 or 4.0 + 2.5 lb/acre. The greatest reduction in growth of autumn fern was observed with the high rates of oxadiazon, oxadiazon + pendimethalin, and oxadiazon + prodiamine. Reductions in rochford's japanese holly fern growth were most severe when plants were treated with the high rate of trifluralin + isoxaben resulting in a 66% and 72% decrease in frond length and frond number, respectively. There were also reductions in frond length and number of fronds when treated with the high rate of oxadiazon + pendimethalin. There were no reductions in frond numbers on tassel fern with any herbicides tested. However, there were reductions in frond length from four of the 10 herbicides evaluated. The most sensitive fern to herbicides evaluated in 2004 was variegated east indian holly fern with reductions in frond length and number of fronds with four of the 10 herbicides tested. Southern wood fern appeared to be quite tolerant of the herbicides tested with the exception of the high rate of oxadiazon. Granular prodiamine 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. The durations of both studies were over 120 days giving adequate time for any visual injury to be masked by new growth. However, there was significant visual injury observed on the rochford's japanese holly fern treated with isoxaben at 60 and 90 days after treatment, which might reduce their early marketability.

Full access

Terminal stem cuttings, 15.24 cm in length, of Chionanthus retusus Lindl. & Paxt. (Chinese Fringetree) were taken on 24 Sept. 1992. All cuttings were made from hardened off current years spring growth. The basal end of the cuttings were cut at an angle and treated with one of eight treatments before being stuck in a 100% vermiculite medium and placed under intermittent mist with a polyethylene covering. Treatments were: 3,000, 8,000 and 16,000 ppm IBA as K-IBA liquid quick dips and as commercial talc preparations (Hormex Nos. 3, 8 and 16), 10,000 ppm NAA as a quick dip, and an untreated control. Cuttings were harvested and evaluated on 10 Dec. 1992. All auxin treatments increased rooting %, average root length, total root fresh weight, and root rating when compared to the untreated control. Cuttings treated with 10,000 ppm NAA had the greatest rooting %, longest average root length, greatest root number, and highest root rating compared to the other auxin treatments, with the exception of the 16,000 ppm K-IBA quick dip treatment which was similar.

Free access

Seed geraniums (Pelargonium × hortorum Bailey `Scarlet Elite') were grown in 10-cm pots in a 1 pine bark : 3 peat : 1 perlite (v:v) medium from 17 April until 1 June 1992. Plants were watered with conventional overhead irrigation (CI) or in ebb and flow troughs (EF) and fertilized with Peter's Geranium Special 15N-6.5P-12.5K (PGS) or Osmocote 14N-6.1P-11.6K (OS). Fertilizer application had no influence on shoot dry weight. Shoot dry weights were greatest for plants given CI. Shoot tissue N was greatest for plants given CI or PGS. Root tissue N was greatest for plants given EF with PGS, and plants watered by CI with OS. Irrigation method had no influence on N remaining in the growing medium. Medium N content was greatest for plants receiving PGS.

Free access