54 BOARD OF AGRICULTURE. [Pub. Doc. 



the fact, but think the death of the vines is due to early 

 maturity. This fact very likely explains why early blight 

 does not attract so much attention as late blight. 



The first indication of the disease is the appearance on 

 the leaves of spots, usually grayish brown, which soon be- 

 come hard and brittle. The disease ordinarily progresses 

 slowly ; the spots become gradually larger, particularly 

 along the edges of the leaves. At the end of two weeks, if 

 the progress of the disease is not interrupted, half of the 

 leaf surface may be brown, withered and brittle while the 

 remainder is of a greenish color. It mav be three or four 

 weeks before all of the leaves are entirely dead. In the 

 mean time the stems keep green, but these finally succumb. 

 The tubers stop growing nearly as soon as the leaves are 

 attacked, and in case of an early appearance of the disease 

 the crop is a failure. 



Anything which interferes with the health of the plant 

 predisposes it to this disease. Whenever the foliage has 

 been injured, as by attacks of the flea beetle, the plant is 

 more liable to the attacks of this fungus. Strong, healthy 

 plants may be entirely free from the disease, while plants 

 which have for any reason been checked in their growth are 

 ready victims. Since vigorous plants are less likely to be 

 attacked, one means of reducing the damage of this disease 

 is to do everything that will keep the plant in healthy 

 growth. Deep plowing, to furnish an abundant supply of 

 plant food ; frequent tillage, to conserve the moisture ; 

 large pieces of well-kept seed, and protection from the 

 flea beetle and Colorado potato beetle will do much to ward 

 off* this disease. 



Bordeaux mixture is an effective preventive of this as of 

 other fungous diseases. It is not a cure but a preventive, 

 and to be of much value it must be thoroughly applied before 

 the trouble presents itself. If the potatoes are treated with 

 Bordeaux mixture and Paris green or other reliable poison as 

 soon as they are two or three inches high, and the applications 

 are followed up after each six inches of new growth of tops, 

 the foliage will be kept healthy and vigorous and free from 

 insect pests, which will in itself tend to lessen the liability 



