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Environmental concerns with nitrogen and phosphorus use at container nurseries and the subsequent effects of nutrient-laden irrigation effluent prompted this study. Bare root liners of willow oak (Quercus phellos L.) and sweetbay magnolia (Magnolia virginiana L.) were grown in #5 containers during year one and repotted into #15 containers during year two using 100% pine bark or pine bark: peat substrate (4:1 by volume). Two fertilizer sources, Osmocote 19N–2.2P–7.5K (19–5–9) or Harrell's 17N–2.2P–10.0K (17-5-12), were included in the container substrate in a fluoropolymer bag with 17 g N in each #5 container and 63 g N in each #15 container. Using a split plot design with fertilizer and media as subplots, a cyclic irrigation regime consisting of three irrigation applications spaced one hour apart was compared to a traditional irrigation regime with one irrigation application that equaled the total volume applied in the cyclic regime. Fertilizer source influenced cumulative amounts (mg/year) of ammonium-N, nitrate-N and orthophosphate in the container leachate. Nitrate-N and ammonium-N from Harrell's 17N–2.2P–10.0K fertilizer were each ≈20% higher in the container leachate from sweetbay magnolia than Osmocote 19N-2.2P-7.5K fertilizer. In the case of the willow oak, the differences were 32% and 19%, respectively. Orthophosphate averaged about 65% greater in leachate from both sweetbay magnolia and willow oak containers when grown with Osmocote compared to Harrell's fertilizer. At the end of year two, height and caliper growth were similar among treatments with both species.
Yellow-flowering magnolias (Magnolia sp.) were evaluated for flower color, bloom duration, and growth rate in U.S. Department Agriculture (USDA), Hardiness Zone 6b, McMinnville, TN. Of the 30 cultivars evaluated, all were reported to have yellow blooms; however, tepal color ranged from light pink with some yellow coloration, creamy yellow to dark yellow. ‘Daphne’, ‘Judy Zuk’, and ‘Yellow Bird’ had the highest yellow color readings on the outside of the tepal and would often be among the latest cultivars to bloom. Magnolia cultivars Gold Star, Golden Gala, Stellar Acclaim, Sun Spire, and Sundance had the lightest yellow tepal color on the outside of the tepal. ‘Goldfinch’, ‘Butterflies’, and ‘Elizabeth’ were the earliest to bloom; ‘Elizabeth’ had one of the longest flowering periods. ‘Carlos’ and ‘Gold Star’ were two of the tallest cultivars in the test compared with Butterflies, Gold Cup, Golden Gift, Golden Pond, Golden Rain, Green Bee, Honey Liz, Koban Dori, Skyland’s Best, and Sunsation, which had the least height growth. Trunk diameters ranged from 7.4 to 18.4 cm after 9 years in the evaluation. Cultivars Golden Gala and Gold Star had trunk diameters greater than twice the size of Golden Pond, Golden Rain, Green Bee, Honey Liz, and Koban Dori. Powdery mildew (Phyllactinia corylea and Microsphaera alni) was observed on all cultivars; however, Golden Sun, Green Bee, Solar Flair, Stellar Acclaim, Sunburst, and Yellow Bird had greater than 47% of the leaf area affected with powdery mildew. Over 60% of the canopy was affected with powdery mildew on ‘Green Bee’, ‘Stellar Acclaim’, ‘Sunburst’, and ‘Yellow Bird’. Powdery mildew was less than 20% on both the foliage and plant canopy of ‘Banana Split’, ‘Butterflies’, ‘Carlos’, ‘Elizabeth’, and ‘Sun Spire’.
One component of container production influencing the water quality concerns in the nursery industry is the amount of container effluent leaching from the container substrate. Potential exists for reduced water use, less leachate volume, and improved irrigation efficiency by altering the container design. This research compares the container leachate volume from a standard, 11.31 (# 3) container with seven 1.9-cm-diameter drainage holes to containers with one, three, or five holes with diameters of 1.9, 0.9, and 0.5 cm. Leachate volume was 41% less (312 to 182 mL) when the diameter of the drainage hole was reduced from 1.9 to 0.5 cm. Nitrate-N was 85% less (3093 to 452 mg) when the container drainage holes were reduced to 0.5 cm. Plant growth and quality of Lagerstroemia fauriei X L. indica `Hopi', crapemyrtle, was similar in all container modifications.
More regulations have an impact on nursery industry today than 10 to 20 years ago, and additional regulations are likely in the future. In view of this, the southeastern nursery industry is taking proactive action by developing a handbook of irrigation and fertilization best management practices (BMP) for container nurseries. Using BMP would be voluntary but could “head off” additional regulations. Additionally, BMP would serve as guidelines for growers 1) attempting to be more environmentally friendly, 2) wanting to promote the fact they are environmentally friendly, and 3) dealing with a complaint from regulatory agencies. Our objective was to develop a BMP handbook that nursery managers could use to find answers quickly to management questions regarding irrigation and fertilization. The handbook was written by university horticulturists, but input and reviews were obtained from industry personnel, additional university personnel, and others associated with the nursery industry. The handbook will be distributed in late summer by the Southern Nurserymen's Association, Marietta, Ga.
Abstract
In field production of nursery stock, plant losses may occur after digging but before plants leave the nursery, thereby reducing profitability. Although little information is available, it appears this plant loss may result from moisture stress induced by root pruning at digging and subsequent handling procedures (2, 3). To ensure adequate roots in the rootball, most nurserymen dig root-balls in accordance with the American Standard for Nursery Stock (ASNS) (1), which allows for increasing rootball size with increased shoot growth.
Abstract
Postemergence and preemergence control of goosegrass [Eleusine indica (L.) Gaertn.] and large crabgrass [Digitaria sanguinalis (L.) Scop.] were evaluated with clopropoxydim, fenoxaprop-ethyl, xylofop-ethyl, and poppenate-methyl. None of these herbicides was injurious to Rhododendron obtusum ‘Coral Bells’, Ilex crenata ‘Compacta’, Euonymus alatus ‘Compacta’, Juniperus horizontalis ‘Plumosa’, or Thuja occidentalis ‘Pyramidal’ and, depending on rate, provided acceptable grass control. Only xylofop-ethyl at 0.12 kg ha−1 and poppenate-methyl at 1.12 kg·ha−1 consistently provided at least 90% control. Poppenate-methyl also provided preemergence activity for one to six weeks. Chemical names used: (E,E)-2-[l-[[(3-chloro-2-propeny)oxy]imino]butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-eyclohexen-l-one (clopropoxydim); (±)-ethyl 2-[4-[(6-ehloro-2-benzoxazolyl)oxy]phenoxy]propanoate (fenoxapropethyl); 2-[4-[(6-chloro-2-quinoxalinyl)oxy]-phenoxy]propionic acid (xylofop-ethyl); and methyl-3-hydroxy-4[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]-pentanoate (poppenate-methyl).
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.
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.
Adoption of biological control tools in woody ornamental nursery production has lagged behind other agriculture fields. One of the major obstacles to adoption is lack of information on the efficacy of various biological control agents in nursery production systems. The predatory mite Amblyseius swirskii, sold commercially as “swirski mite,” is a generalist predatory mite that has recently been adopted as a generalist control for a wide range of mite and insect pests, including thrips (Thripidae), whiteflies (Aleyrodidae), eriophyid mites (Eriophyidae), broad mite (Polyphagotarsonemus latus), and spider mites (Tetranychidae). A controlled-release sachet formulation of swirski mite was evaluated in three experiments to determine whether size of the tree, timing of first application, or sun intensity would affect treatment efficacy. Pest numbers on plants was evaluated biweekly for 12 weeks. The swirski mite sachets controlled broad mite and spider mite outbreaks on red maple trees (Acer rubrum) grown in nos. 3 and 15 nursery containers, respectively. Application at the time of red maple rooted cutting transplant was not necessary to achieve summer-long control of pests. No outbreaks of target pests on flowering dogwood (Cornus florida) in no. 5 containers grown under both full sun and shade, but with low levels of broad mite persisting in the shade treatment and thrips persisting in sun. These results suggest that swirski mite is a promising candidate for biological control in woody ornamental nursery production.
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.