Author(s): Eric Hinesley & Scott Derby
Where Published: HortScience 39: 1020-1024
Date of Publication: 2004
Research Dates: 1998-2001
Subject Area: Shearing Fraser fir (Abies fraseri)

Summary: 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. Shearing 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 int he 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 brnaches 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.

To obtain copies of this report, contact:
Eric Hinesley
Department of Horticultural Science
Box 7609
North Carolina State University
Raleigh, NC 27695-6905
Phone: 919/515-1223
E-mail: eric_hinesley@ncsu.edu

Author(s): Eric Hinesley & Scott Derby
Where Published: HortScience 39: 1644-1646
Date of Publication: 2004
Research Dates: 1998-2001
Subject Area: Shearing Frasier fir (Abies fraseri)

Summary: Fraser fir [Abies fraseri (Pursh) Poir.] Christmas Trees were sheared once annually over a 4-year period 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 2nd-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 approximately 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.

To obtain copies of this report, contact:
Eric Hinesley
Department of Horticultural Science
Box 7609
North Carolina State University
Raleigh, NC 27695-7609
Phone: 919/515-1223
E-mail: eric_hinesley@ncsu.edu

Author(s): James H. Brown & Randall B. Heiligmann
Where Published: Ohio State University, Ohio Agricultural Research & Development Center Special Circular 188
Date of Publication: 2002
Research Dates: 1996-2001
Subject Area: Investigation of the effects of time of shearing, leader length and nitrogen fertilization on bud and limb development, tree taper and density, defects per tree and USDA Christmas Tree grades of West Virginia balsam (Abies balsamea var. phanerolepis) and Fraser fir (Abies fraseri)

Summary: Beginning four years after planting, trees of West Virginia balsam (Canaan) fir and Fraser fir were sheared annually for five years at one of four times: unsheared, August, November and March. For each time of shearing, terminal shoots were sheared to one of four lengths: 10, 12 and 15 inches and a "progressive" combination, in which trees were sheared to 18 inches the first year, 14 inches the second, 12 the third and fourth, and a length to give a even, conical appearance to trees during the fifth year. In addition, trees of one group, with leaders sheared to 12 inches in NOvember, were fertilized annually at the rate of 200 pounds of actual N/acre. Terminal shoots of Canaan fir had consistently higher numbers of lateral buds/shoots per inch of length than did those of Fraser fir, resulting in slightly higher density, fewer defects/tree and higher USDA grades for Canaan fir. USDA grades for trees of both species were highest when terminals were sheared to 10 inches and lowest for those sheared to 15 inches. All unsheared trees were graded as USDA culls. Trees with leaders cut to 10 inches began to reach a 6 to 7 foot marketable size after five shearings and 8 years in the field, while those sheared to 15 inches and the "progressive" combination began to reach marketable size after 6 years. For both species, average USDA grades of trees were highest for trees sheared in August and lowest for those sheared in March. Nitrogen fertilization improved foliage color and weights and needle lengths; however, it did not improve the USDA grade of trees, probably because the overal foliage quality of all trees was judged to be within "characteristics typical of the species."

To obtain copies of this report, contact:
OSU/OARDC
Dr. James H. Brown
School of Natural Resources
129 Williams Hall
1680 Madison Avenue
Wooster, OH 44691
Phone: 330/263-3916
E-mail: brown.14@osu.edu

The Ohio State University
Dr. Randall B. Heiligmann
School of Natural Resources
367 E Kottman Hall
2021 Coffey Road
Columbus, OH 43210
Phone: 614/292-9838
E-mail: heiligmann.1@osu.edu

Author(s): Melvin R. Koelling, MSU Department of Forestry
Where Published: Nursery, Landscape and Christmas Tree Research Projects and Educational Programs
Date of Publication: December 2003
Research Dates: 2000-2003
Subject Area: Pruning and the effect on tree quality and grade in Pinus sylvestris

Summary: Producing the typical 6 to 8-foot Scotch pine Christmas Tree requires an average rotation length of 7 to 8 years. Beginning the third year after planting, the tree is trimmed annually to develop a characteristic "Christmas Tree shape" and to increase foliage density and tree quality.

In the past 20 years, Scotch pine has become an increasingly attractive host for a variety of insect and disease pests. Even with regular and timely pesticide applications, most growers experience significant loss, resulting in reduced harvest yields of 60 to 70 percent of the initial planting.

If rotation length could be reduced by one year, significant increases in yield would occur, and reductions in pesticide applications would result. Modification of shearing practices might permit this to occur provided tree height and quality were not adversely affected. To evaluate the effects of five different terminal shoot shearing practices on tree height and tree grade.

Methods Five different terminal-length shearing prescriptions were established. These were (1) grower normal, which served as a control, (2) 10-inch terminal, (4) 14-14-12-12-10-inch terminal, and (5) 16-14-14-12-10-inch terminal

The trees were sheared according to the prescriptions for each treatment in late June of 2001, 2002 and 2003. In September of each year, total tree height and USDA grade was determined for each tree in each treatment.

Results For all regulated shearing treatments, the maximum total tree height difference is approximately 12 inches. While this difference might be viewed as sizeable, it is not reason for significant concern if trees are sold in the customary 5-1/2 to 7 foot class, especially when increases in average grade are considered. For trees in the 12-inch and 14-inch treatments, height differences were even less, averaging about 0.7 foot.

Of particular significance at the end of the 2002 growing season is the decrease in percentages of No. 3 (cull) trees associated with each treatment. In comparison with the control or grower normal, the percentage of treatment trees with a No. 3 or cull grade averages 9 percent (all treatments).

From an economic perspective, this reduction in cull percentage translates to approximately 109 more trees per acre being available for harvest (9 percent of 1,210 trees per acre). If it is assumed all additional trees are only No. 2s with an average wholesale value of $10 each, an additional $1,090 per acre would be realized by the grower. For the 10-inch, 12-inch and 14-inch treatments, the increase in harvest yield would be even greater, as would the total increase in revenue if some of the additional trees graded No. 1.

Impacts of Research for Scotch Pine Growers Careful attention to regulating terminal shoot length during annual shearing can and does influence tree height and grade. It has been demonstrated that annual shearing following a prescribed shearing regime will result in the production of trees of an acceptable height and with an average higher grade than conventionally followed shearing practices. Furthermore, it is possible to reduce the length of a typical 7 to 9-year rotation and still produce trees of a size readily acceptable to the marketplace.

To obtain copies of this report, contact:
Jill O'Donnell
Michigan State University Extension Service
401 N. Lake Street, Suite 400
Cadillac, MI 49601
Phone: 231/779-9480
E-mail: odonne10@msu.edu