Current Literature 295 



susceptible, though closely followed by pine, hemlock, spruce and 

 balsam. Its greatest ravages are in unthinned stands, especially 

 pure stands of White pine, and infection occurs mainly through 

 broken branches. The annual losses to timber owners in Vermont 

 alone were estimated to be a quarter of a million dollars, so that 

 the losses throughout America each year probably run into many 

 millions. Prevention is best effected by proper thinnings, remov- 

 ing diseased trees and destroying the punks or fruiting bodies; 

 though the practicability of the methods remains to be put to the 

 test in forest areas in America. The lumber from diseased trunks 

 is of very inferior quality, but is usable to some extent in box- 

 making, cooperage, etc. 



J. H. F. 



Larch Mistletoe: Some Economic Considerations of Its Injuri- 

 ous Effects. By J. R. Weir. Bulletin No. 317, U. S. Department 

 of Agriculture. Contribution from the Bureau of Plant Industry. 

 Washington, D. C. 1916. Pp. 25. 



Many of the conifers of North America are subject to attack 

 from one or other of several species of dwarf mistletoes, slender, 

 leafless, yellowish or brownish flowering plants, one to three inches 

 in length, growing in small clumps on the stems and branches 

 of their hosts. In the East the spruces not infrequently fall a 

 prey to one of these pests ; in the West, Lodgepole pine. Yellow 

 pine, Jack pine, Western larch, Douglas fir, hemlock and other 

 species suffer. In this bulletin, Dr. Weir presents the first of a 

 series of economic studies on these parasites — Arceuthobium 

 laricis on Western larch. 



Infection is most abundant in thin, open, uneven, exposed 

 stands, in some cases involving 80 to 90 per cent of the larch, and 

 trees of all ages are susceptible. The effects produced arc witches' 

 brooms, burls, open wounds, through which destructive fungi may 

 gain entrance, stunted growth, and often death. Lumber from 

 diseased trees is inferior in amount and quality. Mistletoe may 

 be controlled by inserting in all timber-sale contracts a clause 

 requiring the cutting on the sales' area of all larches infected 

 with mistletoe, whether merchantable or unmerchantable. 



J. H. F. 



