FUNGI AFFECTING INDIAN CORN 



The Corn Smut 



Ustilago zece-mays 



The smut of Indian corn is one of the most widely 

 distributed and generally known of the fungous diseases 

 of i^lants. It jn-obably occurs wherever this crojo is 

 extensiTely grown, and it has been known for many 

 years. The amount of injury it does varies greatl}^ but 

 has seldom been accurately determined. In the report 

 of the Tenth Census of the United States, Professor 

 Brewer writes that he has heard of instances in which 

 the damage was estimated as high as sixteen per cent., 

 although he had, himself, never seen a field which was 

 injured to the extent of one per cent. Professor Bessey 

 reports that in a garden patch where sweet corn had 

 been grown for several successive years, sixty-six per 

 cent, of the crop was destroyed by smut one season. 

 The general average, the country over, however, prob- 

 ably does not exceed one or two per cent. 



Although corn smut usually infests the ears of the 

 plant, it is occasionally found upon tassel, stem and 

 leaves. On the ear it first appears as a white, malformed 

 mass, representing either the whole ear or a portion of 

 the kernels (Fig. 84). The whiteness gradually becomes 

 darker, finally changing into a brownish-black powdery 

 mass, consisting of millions of the minute spores or 

 reproductive bodies of the fungus. On the tassels the 

 swellings are not so large, and on the stem and leaf 

 their size varies greatly. 



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