THE LILAC MILDEW. 

 Microsphcera Friesii Lev. 



PRELIMINARY. 



THE mildew on lilac is extremely common in the 

 United States, making the upper surface of the leaves 

 look white and moldy from midsummer on. The 

 first stage at which the fungus is ready to gather is 

 when it appears powdery, which is usually in June or 

 July, the earlier collections being the best. The next 

 gathering should be made in the early part of Septem- 

 ber, and another just before the leaves fall. As the 

 leaves bearing the fungus are gathered, lay them in a 

 book or plant-press to dry. If it is possible to examine 

 the first stage with fresh material it will prove more 

 satisfactory, but for the remainder dried material will 

 answer quite as well. 



The required material consists of dried lilac leaves 

 bearing the fungus, gathered in midsummer and 

 autumn ; and potassic hydrate. 



LABORATORY WORK. 



GROSS ANATOMY. 



A. GENERAL CHARACTERS. Notice 



i. The distribution of the fungus over the surface of the 

 leaf. 



