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- Author or Editor: L. Eric Hinesley x
Fraser fir [Abies fraseri (Pursh) Poir.] Christmas trees were cut on 30 Nov. and air-dried for periods of 2, 5, 9, 13, 19, 22, 27 and 33 days, followed by recutting the butt ends and placing in water. Trees dried 9 days or less quickly rehydrated and reached twig moisture contents considerably higher than initial values. The rate and extent of rehydration declined with further drying; trees dried longer than 27 days continued to dry after being returned to water. Needle loss was not related to duration of drying or the quantity of water taken up after trees were returned to water. Xylem pressure potential was closely related to twig moisture content and seemed to be a rapid method of assessing freshness. The critical twig moisture content of Fraser fir, i.e., the moisture content below which a tree will not rehydrate when placed in water, was about 70% to 75%, which corresponded to pressure potentials of -40 to -45 bars.
Three-year-old (3-0) Fraser fir seedlings were transplanted into an irrigated transplant bed at 2-week intervals between 1 Aug. and 15 Oct. and once the following spring prior to budbreak. Following one growing season in the transplant bed, seedlings established the previous August and early September had the greatest dry weight, stem diameter, and shoot elongation.
Two-year-old (2-0) Fraser Fir [Abies fraseri (Pursh) Poir.] seedlings were planted in a transplant bed and grown for 2 years under shade intensities of 0%, 30%, 51%, and 76%. Shade intensity of 30% had little effect on growth, but growth decreased significantly when shade intensity was increased from 51% to 76%. Plants grown in full sunlight or 30% shade were 2- to 2-times heavier and 75% larger in diameter than those grown under 76% shade. The effect of shade was similar for roots and shoots.
Eastern redcedar (Juniperus virginia L.) Christmas trees were cut in early December, brought indoors, and dried to different xylem pressure potentials (Ψ) before the stems were recut and placed in water. Redcedar trees dried rapidly, but quickly rehydrated even at Ψ as low as –6.5 to –7.0 MPa. Trees displayed negligible foliage loss while drying, but those dried to Ψ ≤ –4.9 MPa were predisposed to heavy defoliation following rehydration. There was a linear relationship between Ψ and twig moisture content (dry-weight basis).
Fraser fir [Abies fraseri (Pursh) Poir.] Christmas trees were sheared once annually over a 4-year period using fixed schedules ranging from July to March. Shearng in July reduced potential growth of the upper crown by 38%; when done in October or March, the reduction was about 50%. Length, dry weight, and one-sided area of individual needles were smallest on nonsheared trees, and increased to maximum values on trees sheared in March. In the upper crown (top three internodes), trees sheared in July were 16% to 33% heavier than those sheared in August or later. Dry matter in the upper crown was 30% foliage and 70% woody material. Sixty-one percent of the biomass in the upper crown was branches for trees sheared in July, compared to 55% for October. In the upper crown, foliage comprised about 50% of the branch dry weight (all treatments); in 3-year-old branches, it was 54% to 58%. Among treatments, shearing in July caused the smallest reduction of potential growth and yielded the largest and heaviest branches with significantly more foliage and lateral shoots, all of which would be expected to improve crown density and commercial value. October was the least favorable time to shear.
Fraser fir [Abies fraseri (Pursh) Poir.] Christmas trees were sheared once annually over 4 years on dates ranging from July to March. Shearing reduced total tree growth. Trees sheared in July and August had the highest quality and retail value. Early shearing (July and August) yielded fewer leaders, longer leaders, and 35% to 66% more internodal branches on the leader, compared to later shearing (September through March). Early shearing also yielded more second-order laterals, followed by greater elongation of those laterals. Shearing late into the fall yielded progressively fewer branches, with the minimum in October. Shearing in March gave a little better results than October, but neither date was as good as July or August. In one experiment, two types of residual tip buds (bubble and whisker) were compared as future leaders. Differences in length and straightness of leaders derived from whisker and bubble buds were considered negligible in commercial shearing practice. The ratio of adaxial and abaxial buds on the proximal portion of the leader was about 1:1, and showed little change with shearing date. Distance from the base of the leader to the first abaxial branch also showed little variation among shearing dates.
Postharvest drying of Leyland cypress [× Cupressocyparis leylandii (A.B. Jacks. & Dallim.)] branches was intermediate between eastern red cedar (Juniperus virginiana L.) and Fraser fir [Abies fraseri (Pursh) Poir.] in two laboratory experiments. Leyland cypress rehydrated without adverse effect until xylem pressure potential reached –4.0 to –5.0 MPa (shoot moisture content = 60% to 65%). For branches continuously maintained in water, Fraser fir and Leyland cypress kept equally well over 4 weeks of display, but Leyland cypress lasted longer than Fraser fir over 8 weeks. Postharvest keeping quality of Leyland cypress and Fraser fir was better than that of eastern red cedar.
Dormant branches of Fraser fir [Abies fraseri (Pursh) Poir.] Christmas trees were subjected to single doses of gamma radiation at levels ranging from 0 to 5.0 kGy (0 to 500 kRad). Significant needle loss resulted at doses ≥0.10 kGy and increased with radiation intensity. Irradiation discolored foliage and accelerated drying. Irradiation does not appear to be a viable way to meet insect quarantine requirements on cut Fraser fir Christmas trees.
Fraser fir [Abies fraseri (Pursh) Poir.] Christmas trees up to 3.2 m in height were sampled from 18 well-managed plantations in western North Carolina to determine the yield of decoration greenery (wreaths, roping). Trees were not sidesheared in the year of harvest. The proportion of branch material suitable for decoration greenery decreased with increasing height and crown taper, but crown density had no effect. Mean annual yield of decoration greenery (establishment in the field, until reaching an average height of 3.2 m 10 years later) was 1.9 to 2.3 kg/tree per year, respectively, for trees with medium or heavy crown density.
Various pruning treatments were evaluated to determine the best procedure to correct terminal bud loss in Fraser fir [Abies fraseri (Pursh) Poir.]. Removing the top node (expanding terminal and subterminal buds) soon after budbreak combined with light pruning of the major branches in the next two lower whorls best restored a normal leader. This procedure allowed one or more shoots just below the cut to become orthotropic leaders in the first growing season. All but one of these shoots were removed, and only a single leader was retained after growth matured in late August or September.