Minnesota Plant Diseases. 



133 



gus which is closely related to the last two groups of 

 fungi and particularly to the caterpillar fungus. This fun- 

 gus exerts a strangling action on the host plant. It appears as 

 a whitish or light-tan-colored ring around the young leaves at 

 the tip of the plant. The threads soon form a solid mass en- 

 closing the young leaves and pre- 

 venting them from unfolding. 

 The branch on which the fungus 

 is thus formed may ultimately die 

 off. When the fungus has in- 

 creased somewhat in thickness the 

 sac-spore capsules make their ap- 

 pearance as pear-shaped cavities on 

 the surface of the fungus, just as on 

 the clubbed stalks of the caterpillar 

 fungus. The sacs and spores are 

 also similar to those of this fungus 

 in appearance. The accessory spore- 

 forms appear on the fungus preced- 

 ing the sac-spore forms. The life 

 story in this fungus is thus seen to 

 be simpler than in either the ergot 

 fungus or the caterpillar fungus. 

 No storage organs are developed. 

 (Figs. 57, 58.) 



Other allies of the caterpillar fun- 

 gus (Hypocrcacca in part). Very 

 commonly on the milk mushrooms 

 are found fungi which cause the 

 abortion of the gills of the host and 

 which spread themselves out all 

 over the latter, covering it with a 

 bright red-orange color. On the 

 surface reddish wart-like bodies 

 can be seen and these are the spore- 

 capsules which, as in the caterpillar 

 fungus, open by pores to the sur- 

 face. The sacs are also of a similar 

 shape but the sac-spores are not as long. 



FIG. 58. A strangling fungus. 1. A 

 grass stem with a fungus fruit- 

 ing body, part of which has been 

 removed, showing the sac-spore- 

 capsules in position. 2. A single 

 sac, showing long thread spores. 

 3. A single spore. 2 and 3 highly 

 magnified. 1 after Winter: ? 

 and 3 after Brefeld. 



