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.
Alice Le Duc, Robert P. Adams, and Ming Zhong
Lynn Ellen Doxon and Rex Kirksey
Between 1923 and 1987, several tree species were tested for long-term survival under dryland conditions at the New Mexico State Univ. Agricultural Science Center at Tucumcari. Of those tested, three deciduous species-Chilopsis linearis, Ziziphus jujuba, and Gymnocladus dioica- had a survival rate >50%. Among the evergreen species, Thuja orientalis varieties Goldspire, Gracillis, Berkman, Baker, and Excelsa had good survival rates, as did Juniperus ashei, J. chinensis pfitzeriana, J. pachyphlaea, J. pichottii, J. monosperma and J. virgiana. These species and varieties can be used successfully in dryland plantings in the Western Great Plains once established.
Gary W. Watson, Gary Kupkowski, and Kerstin G. von der Heide-Spravka
Cotoneaster apiculata and Juniperus chinensis `Pfitzeriana Compacta' were planted on a site with compacted clay soil. Plants were placed in holes the same size as the root ball (no backfill), or in holes three times the diameter of the root ball with sloping sides. The three backfill soils used were composed of site-soil (50%) amended with sand (40%) and leaf compost (10%), site-soil (75%) amended with mushroom compost (25%), and unamended site-soil. After 14 months, root density was not different in any of the treatments, and root densities were not different in the compacted clay soil outside of the planting hole, indicating that root growth was not inhibited at the interface between the backfill soil and the compacted site clay soil. Shoot growth of C. apiculata grown in backfill amended with sand and leaf compost was larger than shoot growth of plants grown in other backfills.
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.
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.
Janet C. Cole
Woody plant species were treated in 1995 and 1996 with 0, 1, 2, or 4 lb/acre (0, 1.1, 2.3, or 4.5 kg·ha-1) propazine (a.i.). Species studied in 1995 included rose-of-sharon (Hibiscus syriacus L. `Double Purple'), japanese boxwood (Buxus microphylla Sieb. & Zucc. `Green Mountain'), butterfly bush (Buddleia davidii var. Veitchiana Rehd. `Nanho Purple'), euonymus (Euonymus fortunei var. acutis Hand-Mazz. `Emerald n'Gold'), forsythia (Forsythia ×intermedia Zab. `Lynnwood Gold'), fire thorn (Pyracantha angustifolia Roem. `Gnome'), and japanese spiraea (Spiraea japonica L.f. `Goldflame'). Crape myrtle (Lagerstroemia indica L. `Acoma' and `Zuni') and juniper (Juniperus chinensis L. `Pfitzeriana') were added and euonymus and japanese spiraea were omitted in 1996. In both years, statistical analyses revealed differences in height and visual quality between plants exposed to propazine and control plants of some species; however, differences were inconsistent in that some plants treated with propazine were larger or rated better than control plants while other plants were smaller or of lower quality than their corresponding control plants. In all cases, differences among propazine treatments within each species were <1.2 inches (3 cm) in height while decreases in visual quality compared to control plants were most evident in plants receiving four times the recommended rate of propazine. The horticultural significance of these differences was, therefore, considered small, suggesting that all of the species tested are tolerant to propazine applied at the recommended rate of 1 lb/acre (1.1 kg·ha-1). Chemical names used: 6-chloro-N,N'-bis(1-methylethyl)-1,3,5-triazine-2,4-diamine (propazine).
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
Celina Gómez and James Robbins
analyses were not included, either form of rice hulls appeared to be a suitable media amendment based on mortality and growth data for Pfitzer juniper [ Juniperus × pfitzeriana (L.) Späth]. Laiche and Nash (1990) evaluated the effect of composted rice