186 



GRASSES OF IOWA. 



quality of the product or render the plant less susceptible to 

 the disease. Much in the following pages has been gleaned 

 from various sources, as well as work of our own based on 

 experiments extending over a period of years. 



DOWNY MILDEW. 



This disease is caused by Sclerosporagraminicola (Sacc.) Schroet. 

 Though a large number of plants belonging to many different 



Fig. 83. To the left leaf of SetaHa viHdis containing the oospores of Sclerospora 

 graminicola, & single spore at (a). (After Trelease.) To the right spike affected by 

 the same fangus; (b) single splkelet enlarged. (After Hdlsted.) 



