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Virginia Thaxton, Ed Bush, Ann Gray, and Paul Wilson

Proper irrigation practices are important in the production of container-grown woody ornamentals. When choosing irrigation methods, nurserymen must attempt to maximize production and comply with public policies mandating decreased water usage and runoff. One of these methods schedules irrigation based on plant demand, using tensiometers to measure matric potential of the substrate. While tensiometers have been used successfully with agronomic crops in the field, their effectiveness in irrigation management of large container-grown woody ornamentals has not been extensively tested. The objective of this study was to determine the effect of four irrigation treatments (7 cb tensiometer setting, 14 cb tensiometer setting, 1 time a day application, 4 times a day application) on the production of the ornamental tree Bald Cypress over a 9-month period. Growth differed significantly among treatments. The highest growth index was observed in the 4 times a day and the 7 cb tensiometer treatments, followed by the 1 time a day and 14 cb treatments, respectively. Effluent and leachate (pH, EC, N, P, K) were also measured. Percent effluent volume was highly variable, with maximum volume occurring in June for the 7 cb setting (82%) and in October for the 1 time a day treatment (47%). Higher pH values (7.0 to 8.0) initially occurred in the timed irrigation treatments and higher EC values (2.0–6.0 mmhos) were found in tensiometer treatments; over time, differences among treatments decreased for both variables. Substrate concentrations of N, P and K varied significantly among treatments, while no significant differences were found in the leaf tissue analysis.

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Edward Bush, Ann Gray, Virginia Thaxton, and Paul Wilson

Proper irrigation management is essential for producing quality container-grown woody ornamentals and reducing off-site runoff. Research has shown that tensiometers can be used as an effective tool to schedule irrigation for woody ornamentals. The objective of this experiment was to compare the effect of cyclic and tensiometric irrigation methods on growth of lantana. Lantana camara `New Gold' liners were established in a 3 pine bark: 1 peat:1 mason sand (by volume) medium. Low-tension switch tensiometers were compared to scheduled overhead [one time a day (1×) at 0600 and cyclic irrigation three times a day (3×) at 0600, 1200, and 1800] for the production of 1-gallon lantana plants. Three low-tension tensiometers (1/block) were set at 7 cb and allowed to irrigate over a 12-hour period. Three separate planting dates occurred and then terminated after ≈7 weeks. Tensiometric irrigation increased root and shoot growth compared to scheduled irrigation for the 24 May 1999 harvest date. Cyclic irrigation produced plants with shoot and total root weights >1× and tensiometer treatments for the September harvest date. Tensiometers sharply reduced irrigation requirements compared to scheduled irrigation volume by at least 50% of the 1× and 3× treatments weekly. Analysis of nutrients in leachate for June indicated increased B and Fe concentrations in the 3× irrigation treatment. Lower concentrations of Ca, Mg, and Na were measured in August. Lantana growth was acceptable for all irrigation treatments and harvest dates.

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Edward Bush, Ann L. Gray, Virginia Thaxton, and Allen Owings

Previous research has shown the effectiveness of prodiamine (FactorÆ)as a preemergent herbicide. The objective of this experiment was to evaluate the efficacy and phytotoxicity of prodiamine applied to several woody ornamental and weed species. Phytotoxicity effects were evaluated on eight ornamental species: azalea (Rhododendron indicum `Mrs. G.G. Gerbing'), dwarf yaupon (Ilex vomitoria `Nana'), dwarf mondograss (Ophiopogon japonicus `Nana'), ixora (Ixora coccinea), lantana (Lantana camara `New Gold'), Southern live oak (Quercus virginiana), weeping fig (Ficus benjamina), and daylily (Hemerocallis fulva). Preemergent herbicide treatments (control-nontreated, 2 lbs aia Factor®, and 4 lbs aia Factor®) were applied to ornamentals twice during the experiment at twelve week intervals. There was a reduction in top dry weight for azalea and dwarf mondograss for both 2 and 4 lbs aia treatments. No significant growth reductions were measured for daylily, dwarf yaupon, ixora, lantana, live oak, and weeping fig. The efficacy experiment consisted of four weed species: barnyardgrass (Echinochloa crusgali), crabgrass (Digitaria sanguinalis), coffeeweed (Sesbania exaltata), and pigweed (Amaranthus retroflexus) and five preemergence herbicide treatments (control-nontreated, control-Rout® at 100 lbs/A, Factor® 1 lb aia, Factor® 2 lbs aia, and a tank mixture of Factor® 1 lb aia plus Gallery® 1 lb aia) applied to bark-filled containers. Twenty-five weed seeds of each species were broadcast over each container following herbicide applications. The high rate of Factor®, Rout®, and the combination of Factor®+Gallery® significantly reduced weed dry weight compared to the control. All preemergence herbicides significantly reduced weed counts and height in a similar manner.

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Christina Walsworth, Edward Bush, Ronald Strahan, and Ann Gray

Selective broadleaf weed control is a major economic issue facing commercial landscapers and homeowners alike. Minimal selective post-emergent weed research has been successful in controlling landscape weeds. The objectives of this experiment were to determine the efficacy of seven selective broadleaf herbicides [nicosulfuron (0.66 oz/acre), flumioxazin (8 oz/acre), penoxsulam (2.3 fl oz/acre), bensulfuron (1.66 oz/acre), glyphosate (1% by volume), sulfentrazone (8 fl oz/acre), trifloxysulfuron (0.56 oz/acre) and the control] and to determine the ornamental phytotoxicity on three groundcover species (Liriope muscari, Ophiopogon japonicus, and Trachelospermum asiaticum). A RCBD design was used with five blocks. Each block was split establishing either mulched or bare soil plots (nonmulched). The ground-covers were established three months before herbicide application. On 29 June 2005, four weed species were evenly seeded into the blocks with one hundred seeds each of Sesbania exaltata, Ipomea hederacea, Amaranthus retroflexus, and Euphorbia maculata. Herbicides were applied using a CO2 backpack type sprayer on 6 Sept. 2005. Plant and weed control data were taken to evaluate phytotoxicity and efficacy at 0, 1, 7, 14, and 28 DAT. On 27 Oct. 2005, weeds were harvested from each plot and dried for a minimum of 48 h and weighed. No significant differences in phytotoxicity were observed on either Liriope muscari or Trachelospermum asiaticum. However, there was a significant increase in phytotoxicity exhibited by the Ophiopogon japonicus treated with sulfentrazone compared to all of the other herbicides. Glyphosate demonstrated the best overall control of all broadleaf weeds except Sesbania, while trifloxysulfuron showed the best control of Sesbania. There were no significant differences in herbicide efficacy between the mulched and nonmulched plots. Further research is being done to measure the effects of herbicide efficacy and phytotoxicity in 2006.

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Edward W. Bush, Ann L. Gray, Paul W. Wilson, and Robert I. Edling

Irrigation management is essential in producing quality woody ornamentals and minimizing off-site runoff. The closed-capture effluent device provided an inexpensive method of monitoring effluent in large containers throughout the year with minimal effort. Daily irrigation requirements for `Little Gem' southern magnolia (Magnolia grandifolia) were established throughout an entire growing season. The maximum daily water requirement was approximately 3 gal (11.4 L).

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Edward W. Bush, Don R. LaBonte, Ann L. Gray, and Arthur Q. Villordon

Production of disease-free sweetpotato [Ipomoea batatas (L.) Lam.] transplants is of major importance to certified and foundation seed programs and producers. Sweetpotato roots are traditionally planted and cuttings are harvested from propagation beds. The objective of this study was to investigate the efficiency of producing cuttings in nursery containers. Virus-tested and virus-infected `Beauregard' sweetpotato transplants were harvested from planting beds for the purpose of producing cuttings for transplants. Cuttings were established in 3.7-L plastic nursery containers filled with 100% pine bark amended with either low, medium, or high rates of Osmocote 14-14-14 and dolomitic lime. Resulting transplants produced a greater number of cuttings and greater plant biomass with higher fertilizer rates. Increasing fertilizer rates also had a positive effect on cutting production and biomass. Dry weight and stem growth were similar for both virus-infected and virus-tested transplants following first and second harvests. Producing foundation cuttings in nursery containers filled with a pine bark medium proved to be an efficient method of increasing virus-tested sweetpotato cuttings.

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Edward W. Bush, Ann L. Gray, Paul W. Wilson, and Allen D. Owings

A closed capture irrigation apparatus was designed and constructed for the purpose of monitoring irrigation effluent volume and nutrient analysis from 121-L redwood tree boxes. Measurements were taken monthly from Apr. 1997 to Oct. 1998. Tree boxes were filled with either a 3 pine bark: 1 sand: 1 peat or 3 pine bark: 1 soil media and planted with `Little Gem' magnolia [Magnolia grandiflora (L.) `Little Gem'] or Southern live oak (Quercus virginiana var. virginiana Mill.). In-line, pressure-compensated drip emitters provided irrigation water at the rate of 2 L/h. Daily irrigation volume ranged from 8 L in the fall and spring to 16 L during the summer months. The collection apparatus was constructed from 1-cm angle iron, neoprene rubber, a small drain assembly, and a 22-L plastic container. A square metal frame (43 × 43 cm) was supported by 31-cm legs and draped by a neoprene rubber mat with a drain assembly installed in the center. The drain was positioned into the plastic container creating a closed system to reduce effluent evaporation. The container capacity was adequate to store at least 24 h of collected effluent. This apparatus proved to be an efficient method of collecting irrigation effluent from large containers.