234 SCIENCE REMAKING THE WORLD 



blights, they are more difficult to control. Certain 

 helpful measures have been found effective in check- 

 ing these diseases, but absolute control is yet un- 

 known. 



One of the most dangerous of the European fungous 

 diseases of the white potato is the potato wart. It is a 

 disease of the tubers and from the standpoint of its 

 seriousness and some of its characteristic manifestations 

 it may be thought of as potato cancer, although it is 

 unlike true animal cancer in that it is very infectious. 

 In advanced stages the warty growths on the tubers may 

 be as large as the tuber itself. In severe cases the fun- 

 gous consumes nearly all of the stored food material in 

 the tuber, reducing it to a soft mass. Realizing the 

 possibility of this dread disease being introduced into 

 the United States, an embargo went into effect in 1912 

 against potatoes from countries known to harbour wart. 

 This legislation evidently came a little too late, for in 

 1918 the disease was discovered in gardens at Highland, 

 Pa., a hamlet in the heart of the anthracite coal dis- 

 trict. The alarming discovery of this malady in the 

 United States at once led federal and state officials to 

 launch an extensive campaign to discover the extent 

 of its occurrence in this country. So far it has been 

 found only in gardens, chiefly in restricted areas of the 

 mining districts, in Pennsylvania, West Virginia, and 

 Maryland. Strict quarantine has been placed on these 

 districts and every effort is being made to prevent its 

 spread. This virulent and dangerous disease has rather 

 suddenly become one of the modern potato problems in 

 this country. Immunity to disease in plants is beauti- 



