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Thomas H. Yeager

Three-month-old rooted cuttings of Ligustrum japonicum Thunb. were planted in a 2 pine bark: 1 Canadian peat: 1 sand substrate (by volume) in either 0.75- or 2.2-liter containers and grown for 17 weeks in a greenhouse. One-half of the plants grown in 0.75-liter containers were transplanted to 2.2-liter containers after 11 weeks and grown for 6 weeks in 2.2-liter containers. Shoot dry weights were highest for plants grown 17 weeks in 2.2-liter containers and smallest for plants grown 17 weeks in 0.75-liter containers. Root dry weights were similar for plants grown 17 weeks in 0.75-liter containers. The percentage of applied N used by shoots and roots (44% and 8%, respectively) was highest for plants grown 17 weeks in 2.2-liter containers and smallest (30% and 5%, respectively) for plants grown 17 weeks in 0.75-liter containers.

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Thomas H. Yeager

Multiple branched liners of `Mrs. G. G. Gerbing' azaleas (Rhododendron L.) were greenhouse-grown for 16 weeks in 3-liter containers with a common nursery medium. The growth medium of each plant was amended with either 0.5, 1.5, or 2.5 g N from Osmocote 14N-6P-11.6K and irrigated with either 920 ml water twice a week or evapo-transpiration (ET) plus 10%, 30%, or 50%. Shoot dry weights (35 and 35 g, respectively) for plants irrigated with ET plus 30% or 50% and fertilized with 1.5 g of N were larger than plants fertilized with 0.5 or 2.5 g N and irrigated with ET plus 10%, 30%, or 50%. Shoot dry weights of plants irrigated with ET plus 30% or 50% were similar to plants irrigated with 920 ml twice a week when plants received 1.5 g N. Plants that received 920 ml twice a week and 2.5 g N had larger shoot dry weights than plants irrigated with ET plus 10%, 30%, or 50% and fertilized with 2.5 g N. Shoot dry weights increased from 17 to 46 g for the 0.5 and 2.5 g N treatments, respectively, when plants were irrigated with 920 ml.

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Thomas H. Yeager

Multiple branched liners of llex vomitoria were greenhouse-grown in 3-liter containers with a common nursery medium and received either 2.5 g N surface-applied in 1 application as Osmocote (18N-2.6P-10K) or a total of 0, 0.5, 1,5 or 2.5 g N per container from a solution that contained N, P and K in a ratio of 6:1:3. The solution fertilizer was applied either 1, 2, 3 or 4 times per week with total N applied per container equally divided among individual applications, After 26 weeks, shoot dry weights were greatest for plants that received 2.5 g of N as either 2 soluble applications per week or as Osmocote applied once at the beginning of the experiment. Plants that received 1.5 g of N applied 4 times per week had similar shoot dry weights. Nitrogen uptake will be calculated to determine if 4 applications par week resulted in greater utilization than 2 applications par week or 1 application of Osmocote during the growing season.

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Thomas H. Yeager

Ilex vomitoria Ait. `Nana' root and-shoot growth increased as rate of fertilizer applied from a 6N-1P-3K solution increased from 0.5 to 2.5 g N/3-liter container during a 26-week experiment. Percentage of applied N, P, and Kin the plant and growth medium decreased as N applied increased. Dividing the fertilizer among one, two, or four applications per week resulted in similar use of applied N, P, and K. Shoot dry weights for the 0.5 g N/container treatment were less than for the Osmocote (18N-2.6P-10K) treatment (2.5 g N/container), but the percentage of applied N, P, and K in the plant and growth medium (55%, 42%, and 75%, respectively) was greater than for the Osmocote treatment (31%, 15%, and 27%, respectively).

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Thomas H. Yeager

The nursery industry in Broward County, Fla., had to choose between partaking in the resolution needed to achieve 10 ppb total phosphorus discharged to the Everglades or face regulation. The industry decided to pursue the proactive route and implement best management practices (BMPs). Teams of industry personnel were formed to develop the content of the Florida Container Nursery BMP Guide that contained the following chapters: 1) nursery layout, 2) container substrate and planting practices, 3) fertilization management, 4) container substrate nutrient monitoring, 5) irrigation water quality, 6) irrigation application, 7) irrigation uniformity, 8) erosion control and runoff water management, 9) pesticide management, and 10) waste management. Each team was to determine the content of their chapter, based on cultural practices producers were currently using, or could be using, which would minimize or reduce surface water movement of phosphorus from the nursery to adjacent water. Cultural practices, brought forth after a consensus was achieved by each team in concert with governmental agencies, associations, and allied industries, were meshed with research information, or the “best” information available from academic sources to ensure that the resolutions or BMPs that were written would contribute to resolving the confl ict (i.e., elevated total phosphorus in canal waters). Consensus development is a new challenge for most academicians but it is important because unbiased and science-based knowledge is needed to assist in BMP development. Furthermore, consensus of those directly and indirectly involved in the nursery industry helps facilitate the use of BMPs. Once the Florida Container Nursery BMP Guide is adopted by rule under the statutory authority of the Florida Department of Agriculture and Consumer Services, nursery operators voluntarily using the BMPs and keeping appropriate records will receive a waiver of liability from cleanup costs associated with contaminated ground or surface water, and be presumed to be in compliance with state water quality standards.

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Thomas H. Yeager

Nursery operators had the opportunity to participate in a process to develop a voluntary incentive-based regulation that consummated the consensus of nursery and regulatory personnel regarding the best fertilization and irrigation cultural practice information available for producing plants in containers. Florida Department of Agriculture and Consumer Services (FDACS), which has statutory authority to develop and adopt practices by administrative rule, administered the process, and they relied on university extension personnel to provide education so nursery operators would be prepared to implement practices consistent with the regulation. Nursery operators who voluntarily implemented these practices received a waiver of liability from the recovery costs associated with the cleanup of groundwater contaminated with nitrate nitrogen if each of the following activities had taken place: 1) a notice of intent was filed with FDACS to implement accepted practices; 2) practices based on consensus of the industry were used and guidelines followed; and 3) fertilization and irrigation records were maintained. Participation in an industry-driven regulatory program where nursery operators agreed to use the best cultural practices available prior to the identification of a specific groundwater issue was a significant proactive step for the industry.

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Jeff B. Million and Thomas H. Yeager

The capacity for container-grown plants to capture sprinkler irrigation water plays a critical role in adjusting irrigation rates to deliver required amounts of water to the container substrate. The capture factor (CF) used to describe this capacity was defined as the amount of water captured with a plant relative to the amount captured without a plant. A wind-sheltered, irrigation test area was established to measure CF as affected by plant species, plant size, container size, container spacing, and sprinkler type. CF values for 11 marketable-sized, commonly grown plant species ranged from 1 to 4 with highest values exhibited by plant species with an upright, spreading growth habit. CF values increased as plant size increased. Close container spacings (less than one container diameter between adjacent containers) reduced CF when the allotted area outside the container limited the potential amount of water that could be captured. Compared with impact sprinklers, wobbler sprinklers increased irrigation capture 7% for Ligustrum japonicum grown in 27-cm-diameter containers but not in 16-cm-diameter containers. Results showed that CF is a dynamic parameter that depends on canopy size, container size, container spacing, and sprinkler type. A working knowledge of CF is crucial for determining irrigation requirements to maximize sprinkler irrigation efficiency in container nurseries.

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Richard C. Beeson Jr. and Thomas H. Yeager

Marketable size plants of sweet viburnum (Viburnum odoratissimum Ker-Gawl.), waxleaf ligustrum (Ligustrum japonicum Thunb.), and azalea (Rhododendron spp. L. `Southern Charm') grown in 11.4-L containers were irrigated with overhead impact sprinklers at container spacings ranging from 0 to 51 cm apart. Water reaching the substrate surface was quantified and the percentage of that applied calculated as percent capture (% capture). Percent capture is defined as the percentage of water falling above the plant within a projected vertical cylinder of a container that reaches the substrate surface. For all species, % capture increased linearly with the decline in adjacent canopy interaction, which results from canopies extending beyond the diameter of a container. Increases in total leaf area or leaf area outside the cylinder of a container, in conjunction with increasing distance between containers, were significantly (P < 0.05) correlated with increases in % capture for ligustrum and viburnum. Increases in % capture partially compensated for decreases in percentage of production area occupied by viburnum containers as distances between containers increased, but not for the other two species. Under commercial conditions, optimal irrigation efficiency would be achieved when plants are grown at the minimum spacing required for commercial quality. This spacing should not extend beyond the point where canopies become isolated.

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Geraldine J. Cashion and Thomas H. Yeager

Multiple branched liners of Rhododendron sp. cv. Duc de Rohan were potted in 3-L containers using a 5 pine bark: 5 Florida peat: 1 sand medium (by volume) amended with Prokote Plus (20N–1.3P–8.3K, 9.2 kg·m–3) and placed on one of five treatment platforms (1.2 × 2.4 m) in a commercial nursery in Manatee County, Fla. Treatments were 88 plants per square grid with containers touching (T1), 44 plants per square grid with containers touching (T2), 44 plants per square grid with containers touching in rows and 15 cm between rows (T3), 22 plants per square grid with containers touching (T4), and 22 plants per square grid with 15 cm between containers in rows and 15 cm between rows (T5). Irrigation was applied by overhead impact nozzles (0.13 cm/0.5 h) before collecting runoff. Runoff volume was measured and ppm nitrate N determined on day 6, 23, 38, 63, 92, 161, 189, 217, and 274. Average nitrate N ranged from 97 ppm for T1 to 10 ppm for T5 and corresponded to volumes of 19 and 20 L, respectively. Volumes were not different due to spacing or number of containers; however, nitrate N increased linearly with container number when containers were touching (T1, T2, and T4). Nitrate N in runoff was similar for the same number of containers regardless of spacing.