152 Minnesota Plant Diseases. 



well defined but may extend out indefinitely over the attacked 

 organ. Many fruit rots are caused by these fungi, as the brown 

 rot of plums and ripe rot of apples. Sometimes the influence 

 of the fungus causes the fall of the leaves with great injury to 

 the plants, as on currant bushes. Some imperfect fungi; more- 

 over, attack stem portions, particularly the young stems, and 

 then may do considerable damage. Many are, on the other 

 hand, saprophytes and as such, just as the majority of black 

 fungi, are important agents in the disintegration of plant debris. 

 (Figs. 35, 70, 156 to 159, 164, 165.) 



