THE POTATO 109 



grow but little after the leaves are first attacked; hence 

 the crop is ruined unless the blight can be checked. 



The ravages of leaf blight can be almost if not wholly 

 prevented by spraying the plants with the Bordeaux mixture 

 (see page 208). This solution is applied with a spraying 

 machine at the rate of about fifty gallons to the acre. From 

 three to five sprayings during the season are required when 

 leaf blight threatens. One pound of Paris green to the 

 acre at the first spraying, and the same amount later in the 

 season will also destroy the potato beetles, which often prove 

 such a pest. 



Late blight, or rot. The blotches and blackish 

 streaks often seen running through tubers are caused by 

 late blight, or potato rot. This disease first attacks the 

 leaves and stems, causing them to soften and decay, pro- 

 ducing a bad smell. Late blight often appears suddenly, 

 and spreads through a field with great rapidity. A green, 

 healthy-looking field may turn almost black in a day or two. 



The treatment for late blight is the same as for leaf 

 blight, and should never be neglected in regions where 

 blight is common. It is far better to begin the spraying 

 before either form of blight begins to appear, for this is the 

 easiest time to prevent it. 



TOPICS FOR INVESTIGATION 



1. What is the acreage of potatoes raised on your 

 home farm this season? If you are not certain, go out and 

 measure the field carefully. Compare the acreage of each 

 of the farms represented in the school. 



2. What is the yield of your potatoes per acre? How 

 does this compare with the other farms of your vicinity? 

 With the state? With the United States? 



3. Select two medium-sized potatoes, one regular, 

 smooth and with shallow eyes, and the other irregular and 

 with deep-set eyes. Weigh each. Pare both potatoes, as 



