PLATE VIII 

 Phytophihora infestans: Infection of potato plots 



Fig. I. — A comer of the plots where infected seed potatoes were planted. An epi- 

 demic originated from shoots which became infected through the parent tuber. The 

 four rows of potatoes that still remain standing were of a resistant variety. 



Fig. 2. — The area within the white lines shows a spot where infection is much more 

 prevalent than in the surrounding plants. This spot functioned as a center for the 

 development of an epidemic of late-blight in this field. 



