24 BULLETIN 31*7, U. S. DEPARTMENT OP AGRICULTURE. 



eliminate some of the worst fungous enemies of the forest. Those 

 of the roots escape and others attacking the aerial portion of the 

 tree afterwards in many cases develop quite as vigorously on the dead 

 wood as before. On the other hand, the mistletoe plant dies with 

 the death of the host. Although the seeds of the mistletoe are ex- 

 pelled from the pericarp with considerable force, they are not carried, 

 even though aided by wind, for great distances, as are the spores of 

 fungi. Birds and rodents 2 are factors in the distribution of mistletoe 

 seeds, but the actual service rendered the parasite by such agencies is 

 very small. It is very evident, then, that no trees, young or old, in- 

 fected with mistletoe should ever be selected for seed trees, because 

 all young growth beneath such trees and in the near vicinity would 

 be in great danger of infection. By a gradual process of elimination 

 en every timber-sale area, governed by a clause in the contract requir- 

 ing the taking down or girdling by fire of every mistletoe-infected 

 tree, much may be accomplished within a comparatively short time. 



CONCLUSIONS. 



The principal conclusions which may be drawn from the present 

 study are summarized as follows : 



The deterioration of the western larch in the more open and 

 exposed stands of the Whitman National Forest is due to mistletoe. 

 Although yellow pine and Douglas fir are the most valuable species, 

 the larch, when free from mistletoe, attains a size on any site, so 

 far as observed, sufficient to merit its being carried along in the 

 rotation with the other species. From the fact that the larch mistle- 

 toe finds its optimum development in the more exposed sites, future 

 silvical operations should aim at confining the larch to moist bottoms 

 and protected valleys. 



Since the principal defects of the western larch, excluding 1 pitchy 

 butt and shake, originate from mistletoe, the diameter and age limit 

 of this tree may be greatly extended, provided methods for the 

 eradication of the mistletoe are adopted. 



The larch mistletoe attacks' trees of all ages, from seedlings to the 

 unsuberized parts of mature trees. If not entirely suppressed or 

 killed, trees attacked in early life seldom produce a good grade of 

 merchantable timber. All trees seriously infected show poor health 

 and reduced diameter or height. Trees becoming infected in middle 

 life may have the quality of the timber reduced by the large knots 

 formed by the basal branch burls. 



1 The common English sparrow has been observed by the writer to feed upon the seeds 

 of the yellow-pine mistletoe in the city park at Coeur d'Alene, Idaho. Mistletoe seeds 

 have been found in the excrement of birds in mistletoe regions. Birds and rodents fre- 

 quently build their nests in mistletoe brooms and are known by actual investigation to 

 play a minor role in the distribution of the seeds of the parasite. 



