. [Bulletins on forest pathology : from Bulletin , Washington, , 1913-1925]. Trees; Plant diseases. MISTLETOE INJURY TO CONIFERS. 17 yellow pine and Douglas fir (fig*. 15) and is the rule for larch. The stunting effect of these brooms on the trees as a whole was in one instance very interestingly shown by the fact that a middle-aged Douglas fir increased the radial dimensions of its annual rings after the removal by the wind of an immense broom located midway on the trunk. The weight of the brooms on some conifers is very often greatly increased by the accumulation of dead needles,
. [Bulletins on forest pathology : from Bulletin , Washington, , 1913-1925]. Trees; Plant diseases. MISTLETOE INJURY TO CONIFERS. 17 yellow pine and Douglas fir (fig*. 15) and is the rule for larch. The stunting effect of these brooms on the trees as a whole was in one instance very interestingly shown by the fact that a middle-aged Douglas fir increased the radial dimensions of its annual rings after the removal by the wind of an immense broom located midway on the trunk. The weight of the brooms on some conifers is very often greatly increased by the accumulation of dead needles, lichens, etc. (fig. 11). When loaded with snow or saturated with moisture the brooms are more easily broken off by high winds. The ground around the base of heavily in- fected larches is very frequently littered with brooms broken off in this manner, often insuring the death of the tree in case of ground fires. During the early part of October, 1911, an unusually heavy fall of soft snoAV occurred locally over a small area a round Missoula, Mont. The snow ac- cumulated in such quantities on the mis- tletoe brooms of the larches and Douglas firs throughout the area that the ground around the more heavily infected trees was piled high with fallen brooms. The foliage of old and mature mistletoe brooms is usually not as long lived as that of normal branches of uninfected trees. This is not true in the case of young well-nourished brooms. It has been observed to any extent only in old brooms which have begun to tax the food supply of the tree or the branch on which they are located. In the course of one year it was determined that 655 more needles fell from a small but mature broom on a Douglas fir than from a normal branch of a neighboring uninfected tree of the same species. The number of needles falling from the broom totaled 24182°—Bull. 360—16 3. Fig. 15.—Fallen brooms split from the trunk of a Douglas fir and piled about the base of the tree—a serious fire Pl
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