SPRUCE DISEASES 327 



broken. The tree is relatively immune in the earlier stages 

 of growth before heartwood is formed, since wounded sap- 

 wood is largely protected by the resinous substances which 

 are exuded. Infection may also occur by the fungus ex- 

 tending down into the roots and passing into healthy trees 

 where a natural grafting of the roots has taken place. For a 

 more detailed discussion of the life history and control of 

 the wood-rot fungi, see page 64. 



References 



Schrenk, Hermann von. Trametes pini (Brot.) Fr. forma abietis 



Karst. In Some diseases of New England conifers. U. S. Dept. 



Agr. Div. Veg. Phys. and Path. Bui. 25 : 31-40, pis. 6-9. 1900. 

 Atkinson, G. F. Trametes abietis. In Studies of some shade tree 



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



Bui. 193 : 227-235, figs. 83-90. 1901. 

 Hedgooek, G. G. Notes on some diseases of trees in our national 



forests. II. Phytopathology 2 : 73-80. 1912. 

 Hole, R. S. Trametes pini. Fries, in India. The Indian Forest Records 



6:5: 1-26. pis. 1-8. 1915. 

 Hartig, R. Trametes pini Fr. In Wichtige Krankheiten der Wald- 



baume, pp. 43-61, pi. 3. 1874. 

 Hartig, R. Trametes pini Fr. In Die Zersetzungsersoheinungen des 



Holzes, etc., pp. 32-39, pis. 5-6. 1878. 



Red-Bbown Sapwood-Rot 



Caused by Fames pinicola Fries 



This wood-rot of spruce, pine, fir, larch and hemlock is 

 common in the forest wherever conifers grow. Trees in poor 

 health are more frequently affected. The wood is reduced to a 

 red-brown powdery mass, barely held together by anastomosing 

 sheets of mycelium. The sporophores of the causal fungus are 

 very common on fallen logs and dead standing trees. They are 

 conspicuous because of the red varnished margin and cream- 

 colored under surface. This disease is discussed more fully 

 under fir" diseases, on page 165. 



