Family Solanaceae 311 



reddish discoloration on the skin. In cutting across 

 an affected tuber, the flesh is found to be spotted 

 reddish in isolated and scattered places. The 

 trouble usually starts at the stem end and works 

 toward the bud end and inwards. In severe cases, 

 the trouble is indicated by a discolored band, the 

 outside of which may easily be mistaken for late 

 bHght injuries, Phytophora infestans. 



Net Necrosis 



Cause Unknown. 



Tubers often show minute black areas (fig. 58 c) 

 beginning, near the stem end and extending about an 

 inch inwards. It is not known whether the trouble, 

 if such it may be called, has any influence in reducing 

 the yield. However, it is safer not to use tuber 

 seed which shows these minute internal browned 

 specks. 



Black Heart 



Caused by Overheating. 



This trouble is often met on tubers kept in storage 

 pits which are poorly ventilated. In this case the 

 sweating and overheating will cause the tubers to 

 turn black at the heart (fig. 58 e). The same occurs 

 when potatoes are shipped in overheated cars. The 

 remedy is to keep the potatoes as cool as possible, 

 and slightly above the freezing point. 



