HOW TO INCREASE THE POTATO CROP 

 BY SPRAYING. 



CONTENTS. 



rage. rage. 



Colorado potato lieet Ic 3 Other diseases 17 



Blister beetles S Combined treatment for diseases and insects. 18 



Flea-beetles 9 Value of spraying 18 



Cutworms 10 j Spraying appliances 19 



Leafhoppers and plant lice 11 \ How to prepare Bordeaux mixture 20 



Late-blight and rot lo 



THE demand for an increased yield per acre in the potato crop 

 has become urgent. In the year 1915 the average yield of 

 potatoes in the United States was estimated at 96 bushels per acre. 

 In the following year the estimated average jdeld decreased to about 

 80 bushels per acre. 



Two of the causes of low crop yield are insects and diseases. It has 

 been estimated that the total loss from potato diseases and insects 

 in the United States frec^uently is as much as 100,000,000 bushels. 

 In New York 20,000,000 bushels were lost to potato growers as a 

 result of late-blight in 1912. 



COLORADO POTATO BEETLE.' 



Injury by the Colorado potato beetle is the work of both the "slugs " 

 (young, or larvse) and the beetles (adults) . The beetles, after they 

 pass the winter, appear usually at about the same time as the potato 

 plants, lay their eggs, continue feeding, and frequently destroy small 

 areas entirely, especially those grown for garden purposes. On larger 

 areas the species, as a rule, is somewhat less injurious. When the 

 larvae begin to grow, they usually finish the work begun by the 

 beetles, so that in a very short time, or by the time the larvae are 



1 Leptinotarsa deccmlineaia Say. 



Note.— The insects treated in this bulletin are all leaf-feeders. Some of those which 

 feed in the stalks and tubers, viz, the potato stalk-weevil, the common stalk-1/orer, 

 the potato tuber-moth, white grubs, and wireworms, also are very injurious in 

 certain areas, but these are controlled by methods different from those used against 

 the leaf-feeders, and they will be treated in a separate publication. The diseases 

 treated herein are those affecting the I'oUage and are preventable, in the main, by 

 spraying. Other potato diseases affecting the tubers or controllable by seed selection 

 are treated in Farmers' Bulletin 544, Potato-tuber Diseases, and in Department Bul- 

 letin 64, Potato Wilt, Leaf-roll, and Related Diseases. 



