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David R. Sandrock, Jean Williams-Woodward, and Michael A. Dirr

Fifty-four taxa of Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] were assembled and maintained. A protocol for propagation of Atlantic white cedar was established. Plants were grown in containers and in a replicated field plot. Height and width data were recorded from container- and field-grown plants and all taxa were evaluated for growth habit, growth rate, and summer and winter color. Color descriptions of foliage are provided based on the Royal Horticultural Society colour chart. Exceptional taxa were identified based on needle color, texture, growth habit, and growth rate. Superior green forms include Dirr Seedlings 1 and 2, `Emily', `Rachel', and `Okefenokee'. The superior variegated form is `Webb Gold'. Superior blue forms include `Blue Sport', `Glauca Pendula', and `Twombly Blue', and superior slow-growing forms include `Andelyensis', `Meth Dwarf', `Red Star', and `Heatherbun'. These taxa are recommended to growers, landscapers, and gardeners for production and use.

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David R. Sandrock, Jean Williams-Woodward, and Michael A. Dirr

Five taxa of Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.], `Blue Sport', `Okefenokee', Raulston Form, `Emily', and `Rachel', and one cultivar of Leyland cypress [×Cupressocyparis leylandii (Jacks. and Dallim.) Dallim.], `Haggerston Grey', were screened for resistance to Botryosphaeria and Seiridium cankers. Treatments consisted of Seiridium unicorne (Cke. And Ell.) Sutton, Botryodiplodia Sacc. sp., Fusicoccum Corda. sp. and the non-inoculated control. After 8 weeks, plants were measured for change in caliper at the wound site, change in plant height, and length and width of surface and interior cankers. Seiridium and Botryosphaeria canker development on Atlantic white cedar taxa was not significantly different than that on Leyland cypress. Seiridium unicorne was more pathogenic than Botryodiplodia sp. and Fusicoccum sp. on Atlantic white cedar and Leyland cypress with infection percentages of 100%, 84%, and 80%, respectively. Well-defined, sunken, resinous cankers developed on Leyland cypress plants infected with Seiridium unicorne, whereas Atlantic white cedar showed no visible surface canker.

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L. Eric Hinesley, Frank A. Blazich, and Layne K. Snelling

Hardwood and softwood stem cuttings of 5-year-old Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] were cut to 12-cm (short) or 24-cm (long) lengths, treated with 0 to 15 g IBA/liter in 50% isopropyl alcohol, and rooted in a raised greenhouse bench under intermittent mist. When hardwood cuttings were collected in February, short cuttings survived and rooted better than long cuttings. Survival and percent rooting for softwood cuttings collected in late August was virtually 10070 regardless of cutting length. Long cuttings produced more roots and longer roots with hardwood and softwood material. IBA was unnecessary for rooting, but it markedly increased the number of roots. Chemical name used: 1H-indole-3-butyric acid (IBA).

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L. Eric Hinesley and Layne K. Snelling

Stem cuttings of Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] were collected in early June 1995, divided into two parts (distal tip and proximal segment), and rooted for 12 weeks in shaded containers outdoors. Total rooting was near 80%. Mist intervals of 8 and 15 min yielded the best rooting percentages and the least dieback and injury. Two rooting media were tested, with similar results. Rooting was slightly higher in Spencer-Lemaire Rootrainers (Hillson size), compared to RoPak Multi-pots (#45). More than 90% of the tips rooted, even without IBA treatment. Auxin improved rooting of stem segments, but the difference between IBA at 1.5 and 3.0 g·L-1 was small. Yield of cuttings suitable for transplanting or potting was 80% for tips, 58% for segments. Dividing stem cuttings into two or more parts allows multiplication of rooted propagules from a collection. Chemical name used: 1H-indole-3-butyric acid (IBA).

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Scott A. Derby and L. Eric Hinesley

Germination and growth of atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] was evaluated in response to four container volumes (98 to 530 cm3), two substrates [North Carolina Forest Service (NCFS) container mix [3 canadian peat: 2 coarse vermiculite: 1.5 perlite (by volume), and 3 composted pine bark: 1 peat (by volume)], two controlled-release fertilizers [Osmocote 15N–4.0P–10.0K (15N–9P2O5–12K2O), 12- to 14-month southern formulation, with micros; and Polyon 18N–2.6P–10.0K (18N–6P2O5–12K2O) with micros, 9-month formulation], and three irrigation frequencies (2, 3, or 4 times daily). Although growth increased up to the maximum container volume (530 cm3), the optimum for 1-year-old seedlings appeared to be 164 to 262 cm3. The higher peat content and water holding capacity of the NCFS substrate yielded better growth than 3 bark: 1 peat. Osmocote yielded larger and heavier plants than Polyon, probably owing to more available phosphorus in the former. Irrigation three times daily was optimum. Suitable manipulation of container volume, substrate, fertilizer, and irrigation should yield high quality containerized atlantic white cedar seedlings.

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L. Eric Hinesley and Layne K. Snelling

Drying and rehydration characteristics were measured for Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.], Arizona cypress [Cupressus arizonica var. glabra `Carolina Sapphire' (Sudworth) Little], Leyland cypress [× Cupressocyparis leylandii (A. B. Jacks. & Dallim.)], Virginia pine (Pinus virginiana L.), and eastern white pine (Pinus strobus L.) Christmas trees. Species varied in drying rate, loss of mass during display, water use after rehydration, the relationship between moisture content and xylem water potential (Ψ), and keeping quality. Leyland cypress and Arizona cypress rehydrated from Ψ values as low as –5.0 MPa, and remained in good condition after rehydration. The critical moisture content for Virginia pine and white pine was between –2.5 and –3.0 MPa. The ability of Atlantic white cedar to rehydrate decreased quickly with time out of water, and water consumption dropped sharply within a few days after placement in water. Change in fresh mass varied from +1% for Arizona cypress to –29% for Atlantic white cedar. Keeping quality of Virginia pine was poor, even for trees that were placed in water the day of cutting.

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Laura G. Jull and Frank A. Blazich

Seeds of six provenances (Escambia Co., Ala.; Santa Rosa Co., Fla.; Wayne Co., N.C.; Burlington Co., N.J.; New London Co., Conn.; and Barnstable Co., Mass.) of Atlantic white-cedar [Chamaecyparis thyoides (L.) B.S.P.] were stratified (moist-prechilled) for 0, 30, 60, or 90 days at 4 °C. Following stratification, seeds were germinated at 25 °C or an 8/16-hour thermoperiod of 30/20 °C with daily photoperiods at each temperature of 0 (total darkness), 1, or 24 hours. The germination of nonstratified seed did not exceed 18%. Seeds germinated at 25 °C required 60 to 90 days stratification to maximize germination. In contrast, 30 days stratification maximized germination at 30/20 °C. Regardless of stratification duration, germination was generally lower at 25 °C than at 30/20 °C for each provenance. Averaged over all treatments, seeds of the Alabama provenance exhibited the greatest germination (61%), followed by those from Florida (45%), with the remaining provenances ranging from 20% to 38%. However, specific treatments for each provenance induced germination >50%. Germination of seeds not exposed to light was <8%, in contrast with 48% and 55% germination for daily photoperiods of 1 and 24 hours, respectively. Seeds from each of the provenances, except for Alabama, exhibited an obligate light requirement when germinated at 25 °C. At 30/20 °C, the North Carolina, New Jersey, Connecticut, and Massachusetts provenances required light for germination, whereas the Alabama and Florida provenances did not.

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Laura G. Jull, Thomas G. Ranney, and Frank A. Blazich

Seedlings of six provenances of Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] (Escambia Co., Ala., Santa Rosa Co., Fla., Wayne Co., N.C., Burlington Co., N.J., New London Co., Conn., and Barnstable Co., Mass.) were grown in controlled-environment chambers for 12 weeks under 16-hour photoperiods with 16-hour days/8-hour nights of 22/18 °C, 26/22 °C, 30/26 °C, 34/30 °C or 38/34 °C. Considerable variation in height, foliage color, and overall plant size was observed among plants from the various provenances. Seedlings from the two most northern provenances (Massachusetts and Connecticut) were most heat sensitive as indicated by decreasing growth rates at temperature regimes >22/18 °C. In contrast, plants from New Jersey and the three southern provenances (North Carolina, Florida, and Alabama) exhibited greater heat tolerance as indicated by steady or increasing growth rates and greater top and root dry weights as temperature regimes increased above 22/18 °C. Growth rates of seedlings from the four aforementioned provenances decreased rapidly at temperature regimes >30/26 °C suggesting low species tolerance to high temperatures. There were no significant differences in seedling dry matter production among provenances when temperature regimes were ≥34/30 °C. Net shoot photosynthesis and dark respiration of plants did not vary by provenance; however, net photosynthesis was temperature sensitive and decreased at temperature regimes >26/22 °C. Foliar respiration rates increased as temperature increased from 22/18 °C to 26/22 °C, but then remained relatively constant or decreased at higher temperature regimes. Plants at temperatures ≥34/30 °C exhibited severe stunting, chlorosis, and necrosis on branch tips. However, tissue concentrations of N, P, K, Ca, Mg, Fe, Zn, Cu, and Mn generally increased with temperature regimes >30/26 °C indicating that mineral nutrient concentration was not a limiting factor at high temperatures.

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Jianhua Li, Jeremy Ledger, Peter Del Tredici, and Donglin Zhang

The identity of heath-leaved cypress is controversial. In this study nucleotide sequences of nuclear ribosomal DNA were used to identify heath-leaved cypress (Chamaecyparis `Ericoides') species. Sixteen individuals were sampled representing the five species of Chamaecyparis, `Ericoides', and four other genera of Cupressaceae (Cupressus, Fokienia, Juniperus, and Thuja). The results placed `Ericoides' unequivocally to Chamaecyparis thyoides, supporting a conclusion derived from wood anatomy. This study supports the usefulness and integrity of using molecular data to identify the genetic affinity of cultivars that are morphologically different from the parent species.

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Laura G. Jull, Frank A. Blazich, and L.E. Hinesley

Cones of two provenances (Wayne Co., N.C., And Escambia Co., Ala.) of Atlantic white cedar [Chamaecyparis thyoides (L.) B. S. P.], were collected Fall 1994. Cones were dried for 2 months, followed by seed extraction and storage at 4°C for 6 months. Seeds were graded and stratified (moist-prechilled) for 0, 30, 60, or 90 days. Following stratification, seeds were placed at 25°C or 8/16 hour thermoperiods of 25°/15°C or 30°/20°C with daily photoperiods at each temperature of 0, 1/2, 1, 2, 4, 8, 12, or 24 h. At the conclusion of a 30-day germination period, the Alabama provenance exhibited greater germination than the North Carolina provenance for all treatments (74% vs. 46%). There were no significant differences between 25°/15°C and 30°/20°C with regard to total percent germination for both provenances. Germination was lowest at 25°C for each provenance. In some cases, however, there were no significant differences in germination of the North Carolina provenance when stratified for 60 or 90 days and germinated at 30/20°C or 25°C (61% vs. 63%). There was a highly significant quadratic response to stratification for cumulative percent germination for both provenances. The North Carolina provenance required 90 days stratification to maximize germination (66%) in contrast to the Alabama provenance, which only needed 30 days (80%). Seeds of both provenances did not exhibit an obligate light requirement. However, photoperiods ≥1/2 h increased germination greatly over seeds in darkness (29% vs. 62%).