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Alice Le Duc, Robert P. Adams, and Ming Zhong

Van Melle (1947) proposed that juniper cultivars of the Pfitzer Group were of hybrid origin and ascribed the name Juniperus ×media Melle. This purported hybrid of J. chinensis L. × J. sabina L. has not been accepted unanimously by the horticultural community. Random amplified polymorphic DNAs (RAPDs) were used to analyze and establish new evidence for the hybrid origin of the Pfitzer Group, using both parents and seven cultivars of the Pfitzer Group. Principal coordinate analysis (PCO) of 122 RAPD bands demonstrated that samples of J. chinensis cluster tightly together, as do the J. sabina samples. Cultivars of the Pfitzer Group lacked affinity with either species, but stood apart as a distinct cluster. The data support Van Melle's conclusion that the Pfitzer Group is separate from J. chinensis and indicate hybrid origin from parents J. chinensis and J. sabina. We recognize Juniperus ×pfitzeriana (Späth) Schmidt [Pfitzer Group] as the correct name for cultivars of Pfitzer junipers. Juniperus ×media, proposed by Van Melle, was rendered illegitimate because of the earlier name J. media V.D. Dmitriev.

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Isabelle Duchesne and Jacques-André Rioux

The main objective of this research was to determine the propagation potential of Juniperus scopulorum `Wichita Blue' through grafted cuttings while using Juniperus chinensis `Hetzii' and Juniperus Sabina `Blue Danube' as a rootstock. The experiment took place in a glass greenhouse, the propagation material was either placed under a polyethylene film or intermittent mist. In each of these growth conditions the graft union was either wax coated or buried in a humid substrate. Grafting method was a side veneer graft. Each treatment was repeated three times and the experimental unit was made up of ten specimens.

Best results were obtained from the experimental trial covering the period of february to may (12 weeks). During this trial period we observed a similar rate of successful graft union whether grafted cuttings or conventional graft was used with J. S. `Blue Danube', while grafted cuttings was more successful with J. c. 'Hetzii'. Grafted cutting obtained the best results with J. S. `Blue Danube' when graft union was buried in perlite and placed under an intermittent mist. Rooting quality of rootstock cuttings was slightly inferieur to conventional cuttings for J. S. `Blue Danube' this difference was more prononced in the case of J. c. `Hetzii'

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Edward F. Gilman and Michael E. Kane

Shoot and root growth were measured on Chinese juniper (Juniperus chinensis L. `Torulosa', `Sylvestris', `Pfitzeriana', and `Hetzii') 1, 2, and 3 years after planting from 1l-liter black plastic containers. Mean diameter of the root system expanded quadratically, whereas mean branch spread increased linearly. Three years after planting, root spread was 2.75 times branch spread, and roots covered an area 5.5 times that covered by the branches. Percentage of total root length located within the dripline of the plants remained fairly constant for each cultivar during the 3 years following planting. Root length density increased over time but decreased with distance from the trunk. During the first 2 years after planting, shoot mass increased faster than root mass. In the 3rd year, the root system increased in mass at a faster rate than the shoots. Root length was correlated with root weight. Root spread and root area were correlated with trunk cross-sectional area, branch spread, and crown area.

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Edward F. Gilman and Michael E. Kane

Shoot and root growth were measured on Chinese juniper (Juniperus chinensis L.) Var. `Torulosa', `Sylvestris', `Pfitzeriana' and `Hetzii' 1, 2 and 3 years after planting into a simulated landscape from 10-liter black plastic containers. Mean diameter of the root system increased quadratically averaging 1, 2 m/year; whereas, mean branch spread increased at 0, 33 m/year, Three years after planting, root spread was 2, 75 times branch spread and roots covered an area 5.5 times that covered by the branches. Percentage of total root length located within the dripline of the plants remained fairly constant (71-77%) during the first 3 years following planting. Root length density per unit area increased over time but decreased with distance from the trunk. In the first 2 years after planting shoot weight increased faster than root `weight. However, during the third year after planting, the root system increased in mass and size at a faster rate than the shoots. Root length was correlated with root weight within root-diameter classes, Root spread and root area were correlated with trunk area, branch spread and crown area.

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Calvin Chong and Bob Hamersma

Terminal stem cuttings of four evergreens [arborvitae (Thuja occidentalis L.), `Calgary Carpet' juniper (Juniperus sabina L.), `Hetzii' juniper (Juniperus virginiana L.), and Tamarix juniper (Juniperus sabina L.)] and four deciduous {Amur maple (Acer ginnala Maxim.), common lilac (Syringa vulgaris L.), ninebark [Physocarpus opulifolius (L.) Maxim.], and viburnum (Viburnum farreri Stearn)} woody landscape shrubs were treated with 0%, 0.1%, 0.3%, or 0.8% IBA mixed in talc or with 0%, 0.25%, 0.5%, 1.0%, or 1.5% IBA dissolved in 95% ethanol, radiator antifreeze (95% ethylene glycol), or windshield washer fluid (47.5% methanol). None of the carriers were phytotoxic to the cuttings. Cuttings treated with IBA in radiator antifreeze or windshield washer fluid produced rooting in most taxa similar to those treated with IBA in ethanol. Cuttings of the evergreen taxa produced more roots with liquid than with talc IBA at similar concentration ranges. There were some differences in rooting performance (expressed in terms of percent rooting, mean root count per rooted cutting, and length of the longest root per cutting) of taxa to solvents and IBA concentrations. However, such differences, if any, were generally small or commercially insignificant, except for ninebark, which rooted optimally with no IBA and exhibited a large reduction in percent rooting with increasing IBA concentrations in windshield washer fluid. Chemical name used: indolebutyric acid (IBA).

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Timothy K. Broschat

chinensis ‘Hetzii’ J. Amer. Soc. Hort. Sci. 94 457 459 Pellett, N.E. 1973 Influence of nitrogen and phosphorus fertility on cold acclimation of roots and stems of two container-grown woody plant species J. Amer. Soc. Hort. Sci. 98 82 86 Proebesting E.L. Jr

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Amy L. Shober, Kimberly A. Moore, Christine Wiese, S. Michele Scheiber, Edward F. Gilman, Maria Paz, Meghan M. Brennan, and Sudeep Vyapari

( Gilman and Kane, 1991 ). Juniper cultivars with a wide spreading canopy form (‘Pfitzeriana’ and ‘Hetzii’) had a lower root:canopy ratio (root:canopy spread ratio ≈1.0 to 2.2) compared with cultivars with a more upright canopy (root:canopy spread ratio ≈2