Bui. 82, U. S. Dept of Agriculture. 



Plate III. 



The Cankerous Stage of Sponqospora. 



It is this stage that is most destructive to the potato tuber. The cavities and large pustules 

 combine to cause malformation of the tubers. In C is shown a section through a tuber 

 badly infected with Spongospora. (A, B, D, and E are after Home. C after Gussow.) 



