128 



Minnesota Plant Diseases, 



Ergot fungi (Hypocrcacccc in part). The fungus which pro- 

 duces ergot is a member of the black fungus group, though not 

 a very close relative of the mildews. The life-story of such a 



fungus is somewhat com- 

 plex and we may illus- 

 trate by that of the ergot 

 of rye. In the summer, 

 when the youngest 

 grains are commencing 

 to fill, or just before that 

 period when the grass 

 flower opens, the spores 

 of the ergot fungus may 

 lodge in the flower and 

 start to grow. The 

 young threads are capa- 

 ble of attacking the grow- 

 ing grain and in a short 

 time almost completely 

 absorb the latter, form- 

 ing a more or less soft, 

 spherical or elongated 

 mass of mycelium, at the 

 summit of which are 

 formed, in convolutions 

 of the surface, thousands 

 of summer spores. These 

 are accessory spore- 

 forms. The production 

 of these spores is accom- 

 panied by the formation 

 of sweet saccharine fluids 

 which are very attractive 

 to certain insects. Visit- 

 ing insects become at 

 least partially covered by 

 summer spores in the 



sticky solution and in their visit to other flowers transfer 

 these spores, just as they do the pollen, from flower to flower. 



FIG. 54. Ergot fungus on canary grass; s sclerotium 

 or storage organ of the fungus. Original. 



