Co Bulletin 140. 



color of the foliage changes from a green to a russet or dark brown, 

 or even black, and the edges curl as the tissue dies. A distinguishing 

 characteristic of the early blight is the general appearance of the tissue 

 of the leaf beyond the most seriously affected portions. Instead of 

 retaining the green color of healthy foliage, it assumes a yellowish 

 appearance similar to that of matured plants, this premature ripening 

 probably being caused by the general weakening of the plant. This 

 appearance, no doubt, is the cause of the general supposition that 

 when potatoes are affected with the early blight the death of the vines 

 is due to natural causes, and is simply a case of early ripening, when 

 in reality it is premature and due to the blight. 



One remedy for early blight will have been suggested by what has 

 been said regarding the predisposing causes. It attacks plants which 

 have been for some cause weakened or injured. Treatment, then, 

 should begin with the preparation of the land. Deep plowing to fur- 

 nish an adequate feeding ground and a reservoir for moisture, seed 

 cut in pieces of good size, the surface soil crust broken with a harrow 

 before plants are up, and then thorough tillage and protection from 

 both the flea-beetles and the Colorado beetles. If the plants are kept 

 in vigorous growth they will largely possess immunity to the early 

 blight. 



Bordeaux mixture is the standard remedy for this as well as other 

 fungous diseases. If it has been used in early spring in combating 

 the flea-beetles, and if Paris green is used to kill the Colorado potato- 

 beetles, it is applied in Bordeaux mixture, there is but slight chance 

 that the early blight will appear. The treatment in the manner above 

 described serves a double purpose. The foliage is kept vigorous and 

 healthy, free from attacks of the insect pests, and this alone lessens the 

 liability of attack by the blight as the Bordeaux mixture forms a coat- 

 ing of copper over the foliage thus protecting it. 



Zafe BHi:;ht [PJiytophthora infestaus). 



This is a fungous disease which is responsible for the potato rot of 

 the present season in New York State. * Its appearance is well known, 

 and it has attracted far more attention than has the early blight. 

 The widespread famine in Ireland in 1846 was largely due to the 

 fact that the potato crop was destroyed by the late blight. At the 



