292 



STRUCTURE AND LIFE HISTORIES 



This fungus is known as Albugo Candida, or more recentl)* 

 as Cystopiis candidus. 



4. Downy mildew^ of grapes and cucumbers. 



Fig. 214. — Witches' brooms on the hackberry {Celtis occidentalis), 

 caused by a gall-mite {Phyioplus sp.), or possibly by the mite in conjunc- 

 tion with a powdery mildew {Sphcerotheca phytoptophyla), which is usually 

 found on the "brooms." 



5. Potato rot and "late blight," Phytophthora injestans 

 (Mont.) DeBary. This disease was the cause of the 

 failure of the potato crop and the consequent famine in 



