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Shital Poudyal and Bert M. Cregg

gallons of water, 65% of which was applied as overhead sprinkler irrigation ( Vilsack and Reilly, 2013 ). Irrigation efficiency can be particularly low in container nursery production. In overhead irrigation systems, up to 80% of water applied may be lost

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Steven E. Newman* and Robert O. Miller

Greenhouse and nursery managers rely on testing laboratories with the expectations of accuracy and consistency. The Greenhouse and Nursery Media Analysis Proficiency (GNMAP) Testing program was initiated to provide laboratories servicing greenhouses and nurseries with inter-laboratory quality control. The GNMAP program operational guidelines are based on those outlined under ISO 9000, ISO/IEC Guide 43 and Draft ISO/IEC Guide 24, which describe the requirements for proficiency testing. Nine laboratories enrolled in the program in 2003 and submitted results for root zone media and fertilizer solutions. Data analysis provided the minimum, maximum and median values; median absolute deviation (MAD); overall reproducibility (Rd); individual reported lab values; repeatability (Rp) of lab value (CV for the individual lab); and mean lab value reported. The Rd was calculated from the median of all lab Rp values and is a measure of intra-lab variance. A measure of inter-lab variance was determined by calculating the relative median deviations (RMD = MAD/Median × 100). For one of the media distributed, results for the saturated media extract included median pH values from 4.3 to 6.9 with MAD values averaging 0.1 across the three samples. The electrical conductivity (EC) median values ranged from 0.36 to 4.57 dS/m with RMD averaging 31% of the median. The main variability between laboratories for the majority of the macro cations was closely aligned with measured EC. Cations (K, CA and Mg) concentrations ranged from 17 to 502 mg/L with Ca typically in the greatest concentration. Cation inter-lab precision, based on the RMD ranged from 9-32% across the three substrate samples. The greatest RMD was 31.8% for Ca and 9.2% for K. The Rd values for the cations averaged 5%.

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Thomas R. Gordon, Sharon C. Kirkpatrick, Douglas V. Shaw and Kirk D. Larson

1 Plant Pathology Dept. 2 Pomology Dept. We gratefully acknowledge Lassen Canyon Nursery for providing the land and labor needed to conduct the experiments on which this study is based, and research assistance from B. Aegerter, J. Beales, P

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S. Christopher Marble, Shawn T. Steed, Debalina Saha and Yuvraj Khamare

Weed management in container plant production is challenging, primarily due to limited postemergence herbicide options and the consequential need for supplemental hand weeding ( Case et al., 2005 ). Currently, weed control in container nurseries is

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Jae H. Han, George L. Good, Eric B. Nelson and Harold M. Van Es

Poster Session 3—Nursery Crops 1 18 July 2005, 12:00–12:45 p.m. Poster Hall–Ballroom E/F

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Peter Purvis, Calvin Chong and Glen Lumis

Poster Session 3—Nursery Crops 1 18 July 2005, 12:00–12:45 p.m. Poster Hall–Ballroom E/F

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Scott G. Reeves and James E. Klett

Three commonly used nursery media were packed into 10×40 cm long PVC plastic columns. Two treatments of aqueous applied napropamide [2-(αnapthoxy)-N,N diethyl propionamide] were used including: 1) 13.44 kg/ha, 2) 20.16 kg/ha. Two water treatments were applied to the columns: 1) 2.54 cm/.405 ha, 2) 5.08 cm/.405 ha. Leachate from the columns was collected every three days for a period of two weeks. Quantitative bioassay testing using a napropamide sensitive plant species Hordeum vulgare L. (barley) have indicated a downward linear trend in the growth of roots and shoots when exposed to increasing concentrations of napropamide in controlled petri dish experiments. Preliminary leachate studies indicate that napropamide concentrations in the leachate collected are below levels detectable by the barley bioassay (< .25 ppm) at the label recommended rate of 6.72 kg/ha. Gas chromatography studies will be conducted to confirm napropamide concentrations in the collected leachate.

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P. Tardif, J. Caron, I. Duchesne and J. Gallichand

Overhead sprinkler systems in nurseries use large amount of water and fertilizers and generate runoff losses that may alter the quality of surface or subsurface water. Moreover, the cost associated with these losses is important. Water recycling may reduce that cost and the losses to the environment. Our objective was to evaluate the performance of two recycling systems (recycling and storing water in a tank and recycling solution through subirrigation on capillary mats) relative to a conventional overhead sprinkler system with no recycling. Two species (Prunus × Cistena and Spirea japonica `Little Princess') and seven substrates were used on plots subject to these irrigation practices. Treatments were compared for the water balance and the plant growth. After the first season, preliminary results showed that water and nutrient consumption were 65% less for sprinkler irrigation with recycling and with subirrigation on capillary mats. Plant yield and soil water content were statistically the same for the three treatments.

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B.E. Maust and J.G. Williamson

Experiments were conducted with `Hamlin' orange [Citrus sinensis (L.) Osb.] budded on Cleopatra mandarin (Citrus reticulata Blanco) or Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.] seedling rootstocks to determine minimum container solution N concentrations required for optimum growth and fertilizer uptake efficiency at various growth stages. Plants were fertigated daily with 1 liter of N solution at either 0, 12.5, 25, 50, 100, or 200 mg·liter-1 from NH4NO3 or 0, 3.13, 6.25, 12.5, 25, or 50 mg·liter-1 from NH4NO3 dissolved in a complete nutrient solution, respectively. Percentage of N in the mature plant tissues increased as N concentration in the medium solution increased. Shoot length and leaf area increased as N concentrations increased up to a critical concentration of 15 to 19 mg·liter-1. The critical N concentration for root, shoot, and total plant dry weight was ≈18 mg·liter-1 for `Hamlin'-Cleopatra mandarin nursery plants and 15 mg·liter-1 for `Hamlin'-Carrizo nursery plants. The critical N concentration for relative total plant dry weight accumulation (percentage) for the two experiments was 16.8 mg·liter-1. In a separate experiment, plants were given labeled fertilizer N (FN) (15NH4 15NO3) at one of five growth stages: A) in the middle of rapid shoot extension of the third flush, B) immediately following the cessation of the third flush shoot extension but during leaf expansion, C) immediately following leaf expansion, D) before the fourth flush, or E) in the middle of rapid shoot extension of the fourth flush. Labeled FN recovery increased during rapid shoot extension of the fourth scion flush compared to the other labeling periods. FN uptake per gram of total plant dry weight was greatest during rapid shoot extension (A and E) and lowest during the intermediate labeling periods (B-D). FN supplied 21% to 22% of the N required for new growth during rapid shoot extension.

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Dewayne L. Ingram and Charles R. Hall

The costs of producing ornamental plant species vary among alternative nursery production systems because of differences in planting procedures, growing practices (fertilizing, irrigating, pruning, etc.), and harvesting activities. Common systems