214 



SOUTHERN FIELD CROPS 



FUNGOUS DISEASES 



While the corn plant is subject to a few diseases, these 

 are not known to cause much injury in the South, with 

 the exception of those mentioned 

 below, which injure chiefly the ear. 

 195. Corn smut ( Ustilago may- 

 dis). The presence of this disease 

 is first shown by a large swelling 

 on the ear, the stem, the tassel, or 

 the leaf (Fig. 108). At first, this 

 protruding mass is covered with a 

 whitish skin, which later bursts, 

 setting free clouds of black powder. 

 These powdery particles are the 

 spores, or bodies answering the 

 purpose of seed, and serving to 

 spread the disease to the next year's 

 crop. These spores gain entrance 

 to the young plant after it has 

 appeared above ground. The spread of this disease is 

 due to smut masses left in the soil by a preceding corn 

 crop, or blown in by the wind from surrounding corn 

 fields. No treatment of the seed is effective. 



The method of spread of the disease suggests the means 

 of decreasing it in subsequent crops, by gathering and 

 burning the smut masses before the whitish skin breaks 

 and sets free the spores. On the same principle, rotation 

 of crops is advisable, especially if this results in growing 

 corn on land where no surrounding fields in the preceding 

 year matured smut spores. 



FIG. 107. THE INDIAN 



MEAL MOTH. 

 The larvae injure corn. 

 Enlarged. (Photo by W. 

 E. Hinds.) 



