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Warren E. Copes, Andrew Ristvey, Patricia A. Richardson, Bruk E. Belayneh, Haibo Zhang, John Lea-Cox and Chuanxue Hong

Water quality is an important factor when considering withdrawal of irrigation water from runoff containment basins (RCBs) in ornamental plant nurseries. A water quality standard defines the water quality goals needed to meet the designated use

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Warren E. Copes, Haibo Zhang, Patricia A. Richardson, Bruk E. Belayneh, Andrew Ristvey, John Lea-Cox and Chuanxue Hong

center of nine runoff containment basins (RCBs) and one stream (VA10). Table 2. Mean levels of some macronutrients [potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)] obtained from water samples collected 1 d monthly from 0.3-m depth in the

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Kelly J. Vining, Ryan N. Contreras, Martin Ranik and Steven H. Strauss

amenability to transformation, for invasive ornamental taxa. z Genetic engineering strategies for sterility. A variety of molecular approaches to species or transgene containment have been developed in model species (reviewed in Brunner et al., 2007 ). One is

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Paul W. Bosland and John J. Ellington

Accessions of Capsicum annuum L., a susceptible host, and C. pubescens (R. & P.), a resistant host, were grown in a replicated greenhouse study to test whether antixenosis (nonpreference), antibiosis, or both was the mechanism for resistance to green peach aphid [Myzus persicae (Sulzer)]. A plant choice experiment established that aphids preferred C. annuum to C. pubescens. A no-plant choice test was not undertaken; nevertheless, the aphid's reproductive rates were measured in leaf containment cages and were similar on both hosts. The mechanism of antibiosis was not indicated because fecundity was not reduced in the containment cages; however, other measures of antibiosis were not studied. These observations suggest that antixenosis may be functioning in C. pubescens.

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Annamarie Pennucci

Four novel and five commonly occurring diseases of ornamental nursery stock were evaluated for patterns of dissemination and rapidity of movement within a commercial nursery. Newly acquired but infected nursery stock provided a readily available inoculum source. Dissemination, pathogen movement, and disease development were positively correlated to minimal plant proximities, overhead irrigation, and communal root or soil environments. Water containment and recycling systems allowed movement of waterborne pathogens between plants on the same bench, in the same row, or on contiguous sheets of plastic or landscape fabric. Diseased plants located above uninfected stock or upstream or inside overhead irrigation systems provided a source for rapid aerial spread of conidia. Detached diseased plant parts provided rapid physical movement of pathogens and disease developed despite applications of fungicides. Exclusion of diseased plant materials accompanied by rigorous sanitation offer important means of limiting pathogen movement within the nursery.

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Melissa B. Riley

Herbicide use in containerized plant production nurseries is a vital tool for weed management and the production of plants desired by the consumer. Clemson University researchers have conducted studies aimed at determining the amount of herbicide runoff during normal nursery operation, if herbicides accumulate in containment ponds at nurseries, and how herbicide runoff could be reduced. A 2-year study at commercial nurseries found that herbicide concentrations were higher in containment ponds soon after herbicide application, when compared with months with less herbicide application; and herbicides did not accumulate over the 2-year period. Herbicide runoff was greatest immediately after application and up to 15% of the herbicide applied was lost in the first irrigation event after application when using more water soluble herbicides. Bed material and herbicide formulation were also important in determining the amount of herbicide lost. Total losses were highest from plastic- and fabric-covered beds when using granular formulations and highest from gravel beds when spray formulations were used. The combination of using cyclic irrigation and grass waterways resulted in a reduction of about 25% of isoxaben loss when compared with clay and gravel waterways with continuous irrigation. The effects of reduced herbicide treatments compared to standard spray schedules were evaluated on herbicide transport, weed development, and plant growth and health. Results indicated that plant marketability was not affected, and total herbicide runoff was significantly reduced. Based on these studies, several recommendations can be made to commercial container plant production nurseries, which should reduce herbicide runoff and thereby reduce the environmental concerns associated with nurseries.

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Ted E. Bilderback

Environmentally compatible production practices are conscious efforts to design and retrofit nursery container growing areas to improve irrigation and nutrient efficiency, and reduce exposure of ground and surface water supplies to contaminated effluent. Irrigation of ornamental crops in containers can be very inefficient, using large quantities of water and fertilizer. Irrigation water and fertilizer use efficiencies are directly related to each other. Improving irrigation efficiency improves nutrient efficiency and reduces water volume and nutrients leaving production beds. Increasing efficiency can be accomplished in many ways. Grouping plant species and container sizes into blocks with similar water requirements improves efficiency. Redesigning overhead sprinkler systems to accomplish uniform distribution across growing beds or replacing worn nozzle orifices can significantly reduce application variability. Low volume/low pressure systems that distribute water directly into containers and apply less water in a specific amount of time compared to overhead sprinkler application, will conserve water. Applying irrigation in short cycles rather than long cycles improves wetting in substrates and conserves electrical energy, water and directly reduces nutrient leaching from containers. Creating microclimates in nurseries to optimize light or reduce container temperatures, disease pressure and crop stress can improve water and nutrient efficacy. Flow of water running off growing areas must be engineered to slow velocity, filter and contain effluent. Strategies should be site-specific. Capture, containment and recycling of irrigation water has been a common practice in many nurseries in the U.S., as a means to provide adequate water supplies. Vegetative filter strips adjacent to beds and containment basins have been installed at nurseries to reduce contaminants in runoff before water enters recycle irrigation supplies. In areas with sandy soils, some nurseries have developed closed systems where drainage channels and collection basins are lined to prevent nitrogen movement from runoff into shallow groundwater.

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Wesley R. Autio, Duane W. Greene and William J. Lord

`Summerland Red McIntosh' apple trees (Malus domestica Borkh.) on M.9/A.2, O.3, M.7 EMLA, M.26 EMLA, M.7A, OAR1, and Mark were evaluated over 10 years. Trees on M.7 EMLA and OAR1 were the largest, and trees on Mark were the smallest. Trees on M.7 EMLA produced the highest yields per tree, and those on OAR1 and Mark produced the lowest. The most yield-efficient trees were on O.3 and Mark. The least efficient trees were on OAR1. Fruit from trees on O.3, M.26 EMLA, or M.9/A.2 generally were the largest, and fruit from trees on OAR1 generally were the smallest. Red pigment development was inversely proportional to canopy size, with Mark resulting generally in the most red pigmentation and M.7 EMLA and M.7A generally resulting in the least. Methods of presenting productivity were compared. Presentation of yield per land area occupied or projected yield per planted area were biased in experiments where only some trees naturally would exceed the allotted space and, therefore, were containment pruned and where tree-to-tree competition was directly proportional to tree size. Yield efficiency was a less biased estimate. Further, in single-row planting systems with trees spaced at optimal densities, small trees must be more efficient than large trees to obtain similar yields.

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John A. Barden and Richard P. Marini

Productivity of perennial fruit plants depends to a sizeable degree on partitioning of assimilates between vegetative and reproductive structures. Cultivars and rootstocks modify the partitioning pattern, but there are very few data published on these relationships. The termination of a long-term evaluation of standard-growing and spur-type strains of `Delicious' and `Golden Delicious' on several dwarf and semi-dwarf rootstocks and interstocks provided an excellent opportunity to assess the relationships among cumulative yield, scion weight, and trunk cross-sectional area (TCA). Cultivars were `Goldspur' and `Smoothee' strains of `Golden Delicious' and `Redchief' and `Red Prince' strains of `Delicious'. Rootstocks and interstocks included Malling 9 (M.9), M.26, M.9/Malling Merton 106 (MM.106), M.9/MM.111, M.7, MM.106, and MM.111. Row spacing was standard at 6.1 m. Tree spacing varied with anticipated vigor and ranged from 1.8 to 5.5 m. Pruning times and weight of prunings were recorded in two years. After 18 years, trees were cut off just above the soil line and weighed. TCA and scion weight were highly correlated despite of considerable differences in degree of containment pruning required, and cumulative yields were well correlated with both TCA and scion weight. The ratio of cumulative crop weight to final scion weight decreased quadratically with increasing TCA. Pruning times and weight of prunings were somewhat better correlated with TCA in `Delicious' than in `Golden Delicious'.

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R.D. Berghage

Constructed wetland biofilters have been widely used in recent years to provide secondary or tertiary water treatment, effectively reducing BOD, TSS, nitrate and ammonium, and some organic pollutants from municipal, industrial, and agricultural waste sources. The greenhouse and nursery industries, like all agricultural enterprises, have found themselves under increasing pressure to reduce or eliminate discharge of contaminated wastewater. In response, many greenhouse and nursery operators have installed, and are using, a variety of runoff containment and recirculating irrigation systems. While effective in reducing or eliminating wastewater discharge, these systems can become contaminated themselves and require treatment of the water before it can be reused in the irrigation system. Further, if the water should become contaminated and unusable, environmental discharge of this spent water from a recirculating irrigation system is perhaps even more problematic than simply allowing the excess irrigation water to be dumped in the first place. Potential contaminants in a recirculating irrigation system could include pesticide and other organic residues, excess fertilizer and non-fertilizer salts, and plant pathogens. The primary concern in greenhouse and nursery discharge wastewater is usually fertilizer salts, although pesticide and other organic chemical residues may also be of concern. Biological filtration using constructed wetlands may be a simple low-cost method for greenhouses and nurseries to treat these contaminants.