CHAPTER XXI. 



CORN MILDEW SPRING RUST AND MILDEW. 



Puccinia JRubigo-vera, D.C. 



THE disease of wheat, popularly known under the name 

 of corn mildew, is the best known and most widely-spread 

 of all plant diseases. Agriculturalists are familiar with the 

 reddish spots of ' rust " early in the season, and, later on, 

 the black spots of autumn and winter termed " mildew." 

 These spots are different conditions of the same parasitic 

 fungus, the "rusts" being early conditions of the "mildews." 

 Many observers believe that rusts and mildews have a 

 third condition of growth, and that the mildews of wheat 

 are capable of jumping over an apparent gap and causing 

 a blight of comfrey, bugloss, alkanet, or barberry ; and 

 the blights of these plants, termed jflcidia, in turn being 

 capable of causing new " rusts," and ultimately " mildew " 

 of corn. 



The subject of the mildews of corn may be approached 

 from several points ; and as farmers first become acquainted 

 with the pests every year in the spring, when the stems 

 and leaves of their cereals become rusted, we will start 

 with the familiar rust of spring, premising that botanists 

 term the rust Uredo, and the mildew Puccinia. These 

 terms have been already explained. 



There are two rusts of corn one termed Uredo Rubigo- 

 vera, D.C., the other Uredo linearis, Pers. Both are 

 followed by a Puccinia, the first by P. Rubigo-vera, D.C., 

 and the second by P. graminis, Pers. The first, Uredo, 

 with its Puccinia, is less known and less generally in- 

 jurious than the last ; but as it appears first in the season 



