THE POTATO 



23 



them run together to form large brown blotches, so that 

 the plant is killed and the growth of the tubers ceases. 

 The latter do not rot, however, as in the case of those 

 affected by the Late Blight. 



In the regions where it occurs the Downy Mildew or 

 Late Blight is the most destructive fungous disease of 

 Potatoes. The fungus attacks both leaves and tubers, 

 causing a serious rotting of the latter. Fortunately it 

 can be prevented to a large extent by spraying with 

 Bordeaux mixture, a treatment that also helps in prevent- 

 ing injury by flea beetles and Early Blight. Arsenate 

 of lead is generally added to the fungicide whenever the 

 potato beetles threaten damage. 



