POPLAR DISEASES 



309 



Catise. 



The common white wood-rot of deciduous trees is caused by 

 the fungus Fomes igniarius (= Fames nigricans). The spores 

 from the tubes on the 

 under surface of the 

 sporophores are wind- 

 blown and cause infec- 

 tion through branch 

 wounds where heart- 

 wood is exposed. The 

 mycelium delignifies the 

 wood elements and 

 partially destroys the 

 cellulose. For a more 

 detailed discussion of 

 the life history and con- 

 trol of the wood-rot 

 fungi of living trees, 

 see page 64. 



Fig. 61. — Lengthwise section through 

 fruitiug-body of Fomes igniarius. 



References 



Schrenk, Hermann von, 



and Spaiilding, P. 



White heart-rot 



caused by Fomes igniarius. In Diseases of deciduous forest trees. 



U. S. Dept. Agr. Bur. PI. Ind. Bui. 149 : 26-37, pis. 1-3. 1909. 

 Schrenk, Hermann von, and Spaulding, P. Heart-rot caused by Fomes 



nigricans. In Diseases of deciduous forest trees. U. S. Dept. 



Agr. Bur. PI. Ind. Bui. 149 : 42-^14. 1909. 

 Atkinson, G. F. Polyporus igniarius. In Studies of some shade tree 



and timber destrojdng fungi. Cornell Univ. Agr. Exp. Sta. Bui. 



193 : 214-222, figs. 71-79. 1901. 

 Hartig, R. Polyporus igniarius Fr. In Die Zersetzungserscheinungen 



des Holzes etc., pp. 114^123, pis. 15-16. 1878. 

 Hesler, L. R., and Whetzel, H. H. White heart-rot. In Manual of 



fruit diseases, pp. 72-76, figs. 20-21. 1917. 



