THE POTATO IN BRITISH COLUMBIA. 



65 



groups of small nodules brown in colour. These gradually increase in size, become 

 darker, and finally black in colour. 



The disease does not kill the potato-plant and seldom interferes seriously with 

 the growth of the potato-vines. The best time to detect the disease is during digging. 



Any suspicious samples should be forwarded promptly to Mr. J. W. Eastham, 

 Provincial Plant Pathologist, Court-house, Vancouver, B.C., or to the Dominion 

 Botanist, Central Experimental Farm, Ottawa, Ontario. 



Fig. 7. Hollow-heart or hollow-potato 

 (after Gussow). 



Fig. 68. Internal brown-streak or " net 

 necrosis" (after Gussow). 



SOFT-BOTS. 



Soft-rots, which break down the substance of the potato to a soft evil-smelling 

 mass, are generally the work, of bacteria which obtain entrance through mechanical 

 injuries or follow some of the above-mentioned fungi. They develop very rapidly 

 under warm, moist conditions and furnish an additional reason for selecting only 

 sound tubers for storage. 



Fig. G9. Black-heart (after Potato Magazine). 



