FIG. 23. LETTUCE DISEASES. 



a Germinating sclerotium of Sclerotinia libertiana 

 the 'cause of lettuce drop, b. section of fruiting cup 

 (apothecium) showing asci, ascospores and parapnyses 

 of S. libertiana, c. section through sclerotium of A. 

 libertiana, d. germinating ascospore of .S .libertiana (a. 

 to d. after F. S. Stevens), e. Cercospora leaf spot. 



