HOW TO INCREASE THE POTATO CROP BY SPRA^ TXG. 

 OTHER DISEASES. 



17 



Several other diseases of potato foliage should be mentioned, to 

 avoid confusion with late-blight. They are Hsted below in the order 

 of their appearance. 



SUNSf ALD. 



Young potato plants that have made a rapid growth during cool 

 and moist weather may suffer from, hot, bright weather. The leaves 

 droop and wilt, and some are killed, but the plants usually recover. 



Protracted hot and dry weather, complicated by flea-beetle injury 

 and early bhght, results in the injury illustrated i]i figure 19. The tips 

 and margm of the leaves turn brown and dry up. The jield of tubers 

 is reduced in proportion to the loss of foliage. Spraying with 

 Bordeaux mixture 

 greatly reduces the 



injury from 

 burn. 



tip- 



EARLY-BLIGHT. 



Early-blight is a 

 fungous disease 

 which appears in 

 the North before 

 the late-bUght. In 

 the South, how- 

 ever, it is more 

 common on the fall 

 crop. Itishkelyto 

 occur in all sections 

 of the country. 



This disease is 

 marked by the ap- 

 pearance of nearly 

 black spots in the 

 otherwise green 

 leaves. As these 

 enlarge they are 

 marked by faint 

 concentric rings. 

 (See fig. 20.) 

 Eventually the 

 leaves yellow and die, and the tuber yield is reduced 10 to 25 per cent. 



Early-blight attacks weakened plants and is worst upon light soils, 

 not well adapted, by fertility and, moisture supply, to potato growing. 

 When conditions favor, it becomes widespread. 



Fig. 20.— Potato early-blfeht. 



