GRASSES OF IOWA. 



199 



Fig. 89, Powdery mildew of blue grass (Erj/.sip?iegramini8), leaf of blue grass curled; 

 to the right the leaf more magnified, the black spots perithecla, to the right perlthecia 

 more magnflied. (King.) 



Fig. 90. Powdery mildew of bluegrass, Erysiphe graminis, Oidium stage. The leaf 

 to the right hand magnified, the one to the left more magnified, showing the powdery 

 substance. 



