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  • Author or Editor: Charles H. Gilliam x
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Selected fertilizer treatments were applied to vinca (Catharanthus roseus `Peppermint Cooler') in the landscape to determine their effect on growth and nutrient leaching. In plots 0.9 m × 2.3 m, inorganic fertilizers were applied as either a single application of 4.9 g N/m2 pre-plant, or a split application with 4.9 g N/m2 applied pre-plant followed by application of 2.45 g N/m2 at 8 and 12 weeks after planting (WAP). Inorganic fertilizers included 15N–0P–12.6K granular fertilizer, Osmocote 14N–6.0P–11.6K, and Osmocote 17N–3.0P–10.1K controlled-release fertilizers. Three different organically based fertilizers were applied pre-plant and were composed of recycled newspaper amended with animal manures (chicken, beef cattle, or dairy) and adjusted with (NH4)2SO4 to achieve C:N ratios of either 20:1 or 30:1. A standard industry treatment of 13N–5.6P–10.9K (4.9 g N/m2) incorporated pre-plant and 17N–3.0P–10.1K (4.9 g N/m2) topdressed post-plant was also included. Leachates, collected with lysimeters, from inorganic fertilizer plots had lower levels of total N (NO3 + NH4 +) compared to organically based fertilizer plots through 8 WAP. Of the inorganic fertilizer plots, those receiving 15N–0P–12.6K granular fertilizer had higher total N levels at 1, 2, and 4 WAP than other inorganic fertilizer plots. Total N in leachates declined over the study and by 12 WAP were similar among all treatments. Vinca treated with organically based fertilizers (C:N 20:1) had the highest foliar color ratings through 8 WAP; however, color ratings declined thereafter and by 16 WAP had the lowest ratings. Plants treated with organically based fertilizers had greater shoot dry weights 20 WAP and larger growth indices 8 and 20 WAP.

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Five cultivars of buddleia, Buddleia davidii, were exposed to subambient, ambient, and twice-ambient levels of ozone in open-top chambers for 8 weeks during 1995. Plants were evaluated for foliar injury, growth index, and inflorescence characteristics during and following the exposure period. Destructive harvests were conducted at the end of the exposure period to determine the dry weight of both above- and below-ground plant components. All cultivars showed signs of visible injury in the twice-ambient treatment at both 3 and 8 weeks after treatment initiation (WAT). At 3 WAT, `Pink Delight' was the most severely injured, followed by `Opera'. The other three cultivars had similar lower levels of foliar injury. Reductions in growth index as well as dry weight were found for all cultivars in the twice-ambient treatment. The number of developing floral buds and inflorescences was reduced in the twice-ambient treatment for all cultivars. Differences among the cultivars was due to normal differences in growth habit and not due to elevated ozone levels. These data indicate that Buddleia cultivars are sensitive to levels of ozone similar to those found in urban areas of the southeastern United States.

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Each year, over 16 million tons of poultry litter is produced in the United States. Federal and state regulations now limit the amount of poultry litter that can be land-applied, making it difficult to store and dispose of poultry litter. The objective of this study was to evaluate composted poultry litter (CPL) as a fertilizer source for bedding plants at various rates in comparison with commercially available inorganic fertilizers in regard to plant growth and nutrient leaching. Two experiments were conducted to evaluate use of CPL as fertilizer for landscape annual bedding plants. Petunia spp. ‘Celebrity Red’ and Verbena hybrida ‘Quartz Scarlet’ were planted in raised beds simulating an urban landscape. Before planting, 10 inorganic fertilizer or CPL treatments were incorporated into the raised beds, including Peafowl® brand garden-grade fertilizer 13N–5.6P–10.9K (13-13-13) at rates of 4.9 g N/m2 and 9.8 g N/m2, Polyon® 13N–5.6P–10.9K (13-13-13) at rates of 4.9 g N/m2 and 9.8 g N/m2, and CPL at rates of 4.9 g N/m2, 9.8 g N/m2, 19.6 g N/m2, 29.4 g N/m2, 39.2 g N/m2, and 49 g N/m2. Use of CPL incorporated into landscape planting beds as a fertilizer source resulted in plants equal to or larger than plants grown with conventional inorganic fertilizers. Nitrate (NO3) and ammonia (NH4) levels in leachates from plots amended with CPL were comparable with plots amended with commercial inorganic fertilizers and nitrogen (N) levels were in most cases less in plots fertilized with CPL when compared with inorganic fertilizers when the same N rate was applied. Composted poultry litter may not be able to fully replace inorganic fertilizers, but it can reduce inorganic fertilizer requirements and provide an environmentally sound alternative to poultry waste disposal as well as provide beneficial aspects for plant growth in annual bedding plants.

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Abstract

Control of large crabgrass [Digitaria sanguinalis (L.) Scop.] and goosegrass [Eleusine indica (L.) Gaertn.] was evaluated with the preemergence herbicides oryzalin (Surflan), oxyfluorfen (Goal), and metolachlor (Dual) and the postemergence herbicides quizalofop (Assure), fenoxaprop-ethyl (Whip), haloxyfop (Verdict), poppenate-methyl (Trophy), fluazifop-P (Fusilade 2000), and sethoxydim (Poast) when applied alone or in combination. Oryzalin combinations provided maximum preemergence control compared to oxyfluorfen or metolachlor combinations. Greatest preemergence and post-emergence control was obtained with oryzalin or metolachlor applied with poppenate-methyl. Antagonism of preemergence or postemergence control occurred with several combinations of preemergence and postemergence herbicides. In some instances, control was enhanced by using other herbicide combinations. Chemical names used: 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin); 2-chIoro-1-(3-ethoxy-4-ni-trophenoxy)-4-(trifluoromethyl)benzene (oxyfluorfen); 2-chloro-N-(2-ethyl-6-methyl-phenyl)-N-(2-methoxy-1-methylethyl) acetamide (metolachlor); ½(±)-2-[4-[(6-chloro-2-quinoxyalinyl)oxy]phenoxy]propanoic acid¼ (quizalofop); (±)-ethyl 2-[4-[(6-chIoro-2-benzoxazolyl) oxy] phenoxy] propanoate (fenoxaprop-ethyl); 2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid (haloxyfop); methyl 3-hydroxy-4-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]-pentanoate (poppenate-methyl); (R)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid (fluazifop-P); and 2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio) propyl]-3-hydroxy-2-cyclohexen-1-one (sethoxydim).

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A 2-year study evaluated the effects of three weed species: eclipta [Eclipta alba (L.) Hasskarl], prostrate spurge (Euphorbia supina Raf.), and wood sorrel (Oxalis stricta L.) on growth of container-grown `Gumpo White Sport' azalea (Rhododendron eriocarpum), R. x `Fashion', and Berberis thunbergii DC. var. atropurpurea `Crimson Pigmy'. Competitiveness among weed species as ranked from greatest to least was eclipta, prostrate spurge, and wood sorrel. Greater populations of eclipta and prostrate spurge resulted in decreased shoot dry weight of `Fashion' and `Gumpo White Sport' azalea. Prostrate spurge had a similar effect on `Crimson Pigmy' barberry in both small (3.8-liter) and large (15.2-liter) containers, while eclipta reduced shoot dry weight of barberry only in large containers. Wood sorrel had little effect on shoot dry weight of `Fashion' and `Gumpo White Sport' azalea.

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In sweet corn field plots in Alabama, urea-ammonia nitrogen was applied to the soil through underground and aboveground drip fertigation systems. Dry nitrogen in the form of ammonium nitrate was surface band-applied as a control. Nitrogen rates of 67 kg/ha and 135 kg/ha were applied in either 2 or 4 applications by each of the 3 methods. P and K fertilizers were applied to all treatments in a dry form according to soil test recommendations. The underground drip pipe was placed 23 cm beneath the soil surface in each row. Nitrogen (wet or dry) rate of 135 kg/ha produced greater sweet corn yield than the 67 kg/ha rate with no effect of application number on yield in 1988, when rainfall was less than adequate. In 1987 and 1989, when rainfall was adequate, no differences occurred in yields regardless of number, rate, or method of application of nitrogen.

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Preplant-incorporated, preemergence, and postemergence herbicides were evaluated for yellow nutsedge (Cyperus esculentus L.) control and for phytotoxicity to four container-grown woody plants. Preplant-incorporated or preemergence applications of chlorimuron at 0.07 kg a.i./ha or imazaquin at 1.12 kg a.i./ha provided the greatest control of yellow nutsedge. Imazaquin applied at 0.28, 0.56, 0.84, or 1.12 kg a.i./ha suppressed growth of Rhododendron × `Copperman' azalea and Lagerstroemia indica ×sfauriai `Natchez'. All other herbicides tested were safe on the four woody plants evaluated. Chlorimuron provided the best combination of yellow nutsedge control and tolerance on woody ornamental. Chemical names used: 2-[[[[(4-chloro-6-methoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]benzoic acid (chlorimuron); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid (imazaquin).

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Auburn Univ.'s shade tree evaluation is an ongoing study comparing a moderately diverse range of species, varieties and cultivars of larger-growing trees. Initiated in 1980, there were 250 tree selections planted in three replications located at the Piedmont Substation near Camp Hill, Ala. Among the published “fruits” of the evaluation have been critical comparisons of 10 Acer rubrum selections with respect to growth and fall color characteristics; growth rate and aesthetic characteristics of fourteen Quercus selections; growth and fireblight susceptibility of 10 Pyrus calleryana selections; and the best performing trees overall in the first 12 years of the study. The shade tree evaluation has served as an important precedent for initiation of six additional landscape tree tests in Alabama. Besides its benefits as a research project, the shade tree evaluation has provided a living laboratory for a wide range of educational audiences including landscape and nursery professionals, county extension agents, urban foresters, Master Gardeners, garden club members, and horticulture students. Knowledge gained from the shade tree evaluation has also been shared through presentations at many meetings and conferences.

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This study evaluated the effects of nine alternative substrates on herbicide efficacy in container-grown nursery crops: 1) VT (pine wood chips hammer-milled to pass a 0.4-cm screen); 2) USDA (pine wood chips hammer-milled to pass a 0.64-cm screen; 3) AUC (Pinus taeda chipped including needles); 4) AUHM (AUC hammer-milled to pass a 0.48-cm screen; 5) 1 VT: 1 commercial grade pinebark (v/v); 6) 1 USDA: 1 pinebark (v/v); 7) 1 AUC: 1 pinebark (v/v); 8) 1 AUHM: 1 pinebark (v/v); and 9) 6 pinebark: 1 sand (v/v). Each substrate was amended with 6.35 kg of 17–6–12 (17N–2.6P–10K) control-release fertilizer, 2.27 kg of lime, and 0.89 kg micromax per cubic meter. Containers (8.3 cm) were filled on 15 June and three herbicides applied the next day: Rout (oxyfluorfen + oryzalin at 2.24 + 1.12 kg·ha-1), Ronstar (oxadiazon at 4.48 kg·ha-1) and a nontreated control. The next day, containers were overseeded with 25 prostrate spurge seed. Data collected included weed counts 30 and 60 days after treatment (DAT) and weed fresh weights at 60 DAT. Spurge occurred less in the two treatments of 100% pine wood chips followed by the AUC treatment. With spurge, the least weed fresh weight occurred with the USDA and AUC treatments. For example, at 30 DAT, spurge count was reduced by 33%, 40%, and 70%, respectively, when comparing VT, USDA, and AUC to pinebark: sand. Spurge fresh weight at 60 DAT followed a similar trend. With all of the substrates except AUHM, the addition of commercially used pine bark resulted in less weed control. Rout provided superior control followed by Ronstar and the nontreated control. These data show that control of prostrate spurge with commonly used preemergent applied herbicides may actually be improved with some of the alternative substrates currently being tested.

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Seed geraniums (Pelargonium × hortorum Bailey `Scarlet Elite') were grown in 10-cm pots in a 1 pine bark : 3 peat moss : 1 perlite medium from 18 March until 5 May 1993. Plants received Osmocote 14N-6.1P-12.5K and either conventional overhead (CO), drip (DI), or subirrigation (SI). Subirrigation produced greater shoot and root dry weights than CO or DI. Plants grown using DI produced fewer branches than plants grown using CO or SI. Plants receiving SI reached anthesis before plants receiving CO or DI. Method of irrigation had no influence on total root, soil, or leachate N, but SI did increase total shoot N.

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