SEEDLING DISEASES AND INJURIES 15 



References on Frebzing-to-Dbath 



Chandler, W. H. The killing of plant tissue by low temperature. 

 Missouri Agr. Exp. Sta. Research Bui. 8 : 141-309. 1913. 



Zon, R. G. Effects of frost upon forest vegetation. Forestry Quar- 

 terly 2 : 14-21. 1903. 



Hajtig, R. Injuries due to atmospheric influences and fire. In 

 Text-book of the diseases of trees, pp. 282-304, flgs. 167-159. 

 1894. 



Metcalf, H. Diseases of ornamental trees. U. S. Dept. Agr. Year- 

 book 1907 : 483-494, pis. 58-60, fig. 52. 1908. 



Galloway, B. T., and Woods, A. F. Diseases of shade and ornamental 

 trees. U. S. Dept. Agr. Yearbook 1896 : 237-254, figs. 53-57. 

 1897. 



Smothering-D ise ase 



Caused by Thelephora laciniata Fries 



This disease is common and often destructive in seed-beds of 

 spruce, fir and pine. It may, however, occur on trees of any 

 species. The myceHum of the causal fungus does not enter 

 and establish a parasitic relation with the living plant. It 

 grows in the soil and uses decaying vegetable matter as food. 

 A moist and continually humid atmosphere is necessary to 

 furnish ideal conditions for the destructive development of 

 this fungus. When the trees are planted thickly, this fungus 

 produces an abundant growth of mycelium which adheres to 

 the trees as confluent, incrusting, leathery layers. It may 

 ascend to a height of six or eight inches and encompass the 

 trees. At frequent intervals, more or less horizontal shelves 

 project from the fungous layers attached to the seedlings. 

 These shelves may be narrow and coarsely toothed or broad 

 and rosette-like with a lacerated margin. In its active vege- 

 tati\'e condition, the upper surface of the shelf is finely hairy 

 and a rich dark brown with lighter zones of color. When old 

 and somewhat dried, the entire fungous mass adhering to the 

 trees becomes shrunken and a dirty dark brown. 



