Growth of Fraser Fir Christmas Trees In Response to Annual Shearing

Abstract

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.