FUNGI AS CONTRIBUTORY CAUSES OF WINDFALL, 713 



conditions take first place in importance as causing windfall damage, 

 fungi second, and exposure third. 



The principal fungi concerned in causing windfall are Polyporus 

 schzvcinitcii, Tramctcs pini, Echinodontimn tinctorium, Pomes annosiis. 

 Armillaria mellea, and Sparassis radicata. 



Fungi as secondary causes play an important part in causing wind- 

 fall. Poorly drained soils, moist sites, old-age class, fire, and other in- 

 juries, prevalence of fungous infection, all contribute to increase the 

 weakening action of fungi exerted upon the roots and trunks of trees 

 and thus increase the danger and damage from windfall. 



All other factors being equal, a sound tree will withstand windthrow 

 when a tree whose roots arc rotted will be thrown or a tree whose trunk 

 is rotted will be broken. 



A large amount of damage to our Xatit)nal Forests and the remain- 

 ing forest region as well, reckoned upon a financial basis, is annually 

 sustained through windfall. A considerable portion of this loss can be 

 traced to fungous action alone. 



Fungous attack is largely responsible for windthrow in western white 

 pine, one of the most important of our timber trees. It is also a menace 

 through windthrow to all stands of infected timber left as thinned 

 stands or as seed trees after cutting operations. 



It is recommended not only as a measure toward increasing forest 

 sanitation, but primarily as a preventive measure against windfall and 

 windbreakage, that all trees marked to be reserved in selection cuttings 

 or as seed trees upon a cut-over area are to be free from root, butt, 

 and trunk rots. 



IIII'.LKJC.KAI'IIV 



1. Baker, T. T. : A Windfall Problem. For. Quarterly, Vol. XIII, p. 317. I9I5- 



2. Benedict, R. C. : Snow Injury to Trees. Torreya, Vol. 16, p. 71. 1916. 



3. Bernhardt, A. : Influence of Site upon Damage from Windthrow. 1877. 



4. Fernow, B. E. : Economics of Forestry, pp. 185-186. 1902. 



5. Fisher, W. R. : Forest Protection in Schlich's Manual of I'orcstry, Vol. IV', 



p. 527. 1907. 



6. Frothingham, F. II.: Douglas l-'ir. U. S. Dept. .\gr., Forest Service Circ. 



150, p. 26. I')CK). 



7. Fiirst, H. : Protection of Woodlands, pp. 34-42. 1893. 



8. Graves, H. S. : Nineteenth Annual Report, U. S. G. S. Pt. V, Forest Re- 



serves, pp. 86-87. 1897-1898. 



9. Hess, R. \.: Influence of Site upon Storm Injury of Stands. Forstschutz, 



PP- 383-f^>. i'>oo. 

 10. Ilodson, Iv K., and Foster, J. II.: luigelmann Spruce in the Rocky Moun- 

 tains. L'. S. Dept. .\gr., For. Service Cir. 170, p. 9. 1910. 



