Vegetable Gardening 137 



about the proper depth. One piece of seed potato con- 

 taining an eye should be planted to each hill. 



Both the vines and the tubers of potatoes are attacked Insects and 

 by insects and various diseases. The Colorado potato i ne po t a to 

 beetle (" potato bug ") is the commonest and most bu 9 

 destructive insect pest. It lives on the leaves and 

 so can easily be killed with a poison spray of Paris 

 green. 



A common disease of the tubers is potato scab. This Use of 

 is a fungous growth that causes the potato skin to appear 

 rough and unsightly. If potato seed is not perfectly scab 

 smooth, it should be treated with formalin to kill the 

 fungi that might cause disease in the new crop. The 

 treatment consists in soaking the potatoes for two hours 

 in water containing formalin, one pint of formalin to 

 thirty gallons of water being the right strength. 



A disease of the po tato vine which causes it to wilt and Potato 

 die is known as " potato blight." This is also a fungous ig 

 disease, and it can be prevented by spraying the potato 

 vines every ten to fourteen days with Bordeaux mixture, 

 the spray that is used for most fungous diseases. Potato 

 blight does not occur in all parts of the United States. 

 A sudden outbreak of blight in Ireland many years ago, 

 before any remedy was known, resulted in a famine 

 that cost the lives of more than two hundred thousand 

 people. 



Sweet potatoes. That part of a sweet potato which Conditions 

 we eat is a true root and not an underground stem like we%t mn9 

 the tuber of the white potato. As sweet potatoes are potatoes 

 natives of tropical America, they are especially a South- 

 ern crop, though they are grown in the North in warm, 



