LOPHODERMIUM 



249 



Usually saprophytes on dead leaves or stems. 

 Ascophores often gregarious on bleached spots. 



Pine leaf cast (Lophodermium pinastri, Chev. =Hyster- 

 ium pinastri) Schrad.) is the cause of a serious disease to 

 seedling conifers, which results in the leaves being shed ; 

 if this occurs for two or three years in succession the trees 

 are killed outright. According to Hartig the disease may 

 frequently be observed even in the first autumn, by the 



FIG. 71. Lophodermium pinastri. i, fungus on 

 pine leaves ; 2, ascigerous form of fungus ; 3, 

 conidial form ; 4, ascus with spores ; 5, a single 

 spore. Figs. 2-5 mag. 



primary leaves showing brown blotches, while other portions 

 become purple-red. Even at this early stage the character- 

 istic mycelium may be found in the brown blotches. During 

 the first year after infection a large number of minute black 

 spots, representing a conidial form of the fungus, are pro- 

 duced, the contents of which do not appear to be capable of 

 germination. As a rule, the ascigerous form of the fungus 

 does not appear till the following season, but this depends 

 much on the weather. Dry summers and cold winters check 

 the development of the fungus, whereas its growth is favoured 



