New York Agricultural Experiment Station. 157 



Throughout the State late blight was general. Only a few locali- 

 ties escaped its ravages. In most places it was exceedingly virulent, 

 being most destructive to the later planted potatoes. There was some 

 of the disease among early potatoes, but not so much as in 1902. Up 

 to about August 24 there was but little if any damage done to the 

 late potatoes and the prospect for a fair crop was good. Then there 

 came a period of rainy weather and late blight suddenly became ex- 

 ceedingly virulent. Early planted fields were attacked first, but in the 

 end the late planted ones suffered the worst. All through the central 

 and western portions of the State potato fields which should have 

 remained green until October i were entirely dead by September 10 

 or earlier. In many cases the blight was followed by rot which caused 

 still further loss. 



After making a thorough survey of the situation the writers esti- 

 mate that the loss from late blight (Phytophthora iiifesfans) in New 

 York State in the season of 1903 was fifty bushels per acre on an 

 average. Since the area devoted to potatoes in the State is about 

 396,000 acres22 and the average price at the digging time was 50 

 cents per bushel, the total loss sustained by our farmers is almost 

 $10,060,000. A large part of this loss might have been prevented by 

 spraying. 



THE NATURE OF POTATO BLIGHT. 



Farmers use the word blight to indicate almost any injury which 

 causes potato foliage to turn brown and die. Hence, blight may be 

 early blight, stem blight, late blight, flea-beetle injury, paris-green 

 injury, the effects of drought, etc. Lack of space prevents a full 

 discussion of the various forms of blight at the present time. How- 

 ever, a few words on the nature of late blight seem absolutely neces- 

 sary to a proper understanding of the subject of potato spraying. 



It is late blight which is chiefly responsible for the heavy losses on 

 the potato crop in New York during the past two years. Late blight 



^395.640 acres in 1899, according to U. S. census. 



