CHAPTER XX 



The Smut Fungi 



The Smuts form a distinctive group of parasitic plants 

 called by botanists Ustilaginales. The mycelium develops 

 in the tissues of the host plant and causes serious injury to 

 the parts infested. Spores are developed in the form of 

 the blackish powder so characteristic of Corn Smut and 

 Oats Smut. These primary spores germinate under favor- 

 able conditions and often bring about 

 the development of enormous numbers 

 of secondary spores. 



Nearly every one is familiar with the 

 Loose Smut disease which so often 

 affects the heads of oats, causing them 

 to become masses of loose blackish 

 powder instead of healthy kernels of 

 grain. These black powdery masses 

 are composed of millions of the minute 

 spores by means of which the fungus 

 multiplies. 



These spores appear on the plants when the oats in the 

 field are blossoming. At that time the seed envelopes — 

 which later form the " chaff " — are spread apart, so that it 

 is easy for the spores to lodge inside them. There the spores 

 remain, even through the threshing process. 



The spores that have thus been concealed beneath the 

 chaff remain in position until the grain is planted. The 

 moisture and warmth favorable to the starting of the seed 



226 



Smut Sporidia 

 Magnified 



