Results of this study indicate that although trees of West Virginia balsam and Fraser fir can be successfully sheared into quality Christmas trees from mid-summer to early spring, shearing soon after shoot growth is completed and stem tissue begins to harden in mid- to late-summer can result in improved quality as reflected by higher numbers of U.S. Premium and U.S. No. 1 trees, particularly when compared with trees sheared in late winter/early spring.
Specific data collected as part of the study does not provide conclusive evidence of why this occurs, because there were no trends in shoot growth after shearing, numbers of internodal buds and limbs, or tree density related to time of shearing. Based on results in other studies with the pine species (Brown, 1960; Brown, 1964; Brown, 1984), it is possible that when shoots are sheared in late summer when growing conditions are more favorable and before stem tissue begins to harden, inter-nodal buds which are already present along the shoots of the firs can develop/enlarge and produce more vigorous inter-nodal limbs the following growing season.
Also, as noted in previous studies with the pines (Brown, 1981), the shorter terminal shoots of West Virginia balsam and Fraser fir were sheared, the higher the tree quality. In this study, for those with terminals sheared to 10-inch lengths, 100 percent of West Virginia balsam and 59 percent of Fraser fir were graded as Premiums, while for those sheared using the “progressive” treatment, approximately 33 percent of trees of both varieties were graded as Premiums.
However, it should be noted that shearing terminal shoots to shorter lengths increases the time needed to produce harvestable trees; for those on which terminals were cut to 10-inch lengths, trees began to reach harvestable size after five shearings and eight years in the field, while those on which terminals were cut to 15 inches and those sheared using the “progressive” treatment began to reach harvestable size after three shearings and six years in the field.
It is also important to remember that individual trees in this study were randomly assigned to shearing treatments and were not selected based on growth rate, bud set, or lateral branch angle. Experience separate from this study has demonstrated that West Virginia balsam fir trees exhibiting good growth rate and bud set and upward-swept lateral branches can be sheared with terminals even longer than those used in this study and still produce high-quality trees. Such shearing strategies, however, necessitate that trees be growing on good sites with adequate fertility and good weed control.
Annual applications of nitrogen fertilizer had no effect on shoot growth, numbers of internodal buds and limbs, tree density, or overall tree quality as specifically used in assigning USDA grades to trees in this study. However, fertilizing did have some very beneficial effects on tree quality as reflected in foliage characteristics of both West Virginia balsam and Fraser fir, including increased needle lengths; heavier, more dense foliage; and better needle color. These are all traits that can help the overall appearance and marketability of trees.
Other research at the Ohio Agricultural Research and Development Center has shown that annual applications of fertilizer may not be needed to improve foliage quality on harvestable trees; rather, bene-fits of nitrogen applications are usually effective for at least two years, and applications made in the spring of the year prior to harvest will improve foliage characteristics of the two years of needles that are most visible on trees (Brown, 1976; Brown, 1998a; Brown, 2000a; Brown and Vim-merstedt, 1983; Keller, 1980).
For this study, USDA Standards for grading Christmas trees were used to evaluate the effects of various defects on trees and to assign a “quality” value to individual trees. Results found that because of higher numbers of internodal lateral limbs and more ascending branch angles, overall tree quality was generally somewhat higher for trees of West Virginia balsam than for those of Fraser fir. For individual Christmas tree growers, this may or may not result in better sales and/or higher prices.
In Ohio and many other states, most growers use their own subjective criteria rather than USDA grades to judge tree quality, and Fraser fir is well established as THE PREMIUM TREE on the Christmas-tree market. Excellent foliage quality, including the color of the upper and lower surfaces of needles, “stiffer” limbs that support decorations without sagging, and needle retention on cut trees (Heiligmann and Brown, 1997) contribute to that position.