10 



for the roots to feed in, and for the stolons, which are the 

 underground stems that bear the tubers, to penetrate. These 

 stolons run out, on some varieties, a foot or more, and then the 

 end enlarges and develops into the tuber that is dug and 

 harvested. 



Spraying. 



Spraying must accompany the cultivation of the crop, com- 

 mencing as soon as the vines are from 4 to 6 inches high. 



The spraying early in June is chiefly for the purpose of 

 checking the damage by the flea beetle, which sometimes 

 punctures the leaves to such an extent that it not only checks 

 the growth of the vines but gives the spores of early and late 

 blight free access to the tissues of the wounded leaves. 



From the last of June to the second week in July or later, 

 spraying with a poison solution to kill the potato beetle is 

 necessary. They must be kept off the vines by all means, for 

 unless checked they will strip all the leaves from the stalks in 

 a few days and ruin the field. The following is a good spray 

 to kill the potato beetle: 3 pounds arsenate of lead in 50 

 gallons of water. This may be used alone or the 3 pounds of 

 arsenate of lead may be put into 50 gallons of Bordeaux mixture. 



Arsenate of lead is mentioned because it is very effectual in 

 destroying the young beetles, and there is no danger of injury 

 to the foliage as is the case with Paris green. If it is necessary 

 or desirable to use the Paris green, use one-half pound to 50 

 gallons of water, and add 3 to 4 pounds of lime to prevent 

 danger of leaf burn. 



These poisons are used only for the purpose of protecting the 

 vines from insect injury. Spraying with Bordeaux mixture 

 must nevertheless be continued for the more important purpose 

 of preserving the vines from attacks of the late blight caused by 

 the fungus Phytophthora infesians, the worst of all enemies of 

 potato vines. 



The late blight is a fungous disease which may attack the 

 leaves, and later the stalks, of the potato plant at any time in 

 July or August. It first appears as a brown spot on the leaves, 

 as large as a cent or larger, and sometimes it spreads so rapidly, 

 if unchecked, that it soon covers all the leaves. They then 



