FHE MODERN POTATO PROBLEM 233 



DISEASES. Potatoes, like human beings, are subject 

 to serious and destructive diseases. Some of these 

 diseases frequently become epidemic in certain sec- 

 tions of the country, causing almost total loss of the 

 crop. The potato plant may become afflicted with 

 purely physiological troubles but the most destructive 

 diseases are parasitic in origin. As in the case of 

 animals, these pathogenic organisms are of several 

 different types. Although fungous diseases are rare 

 in animals they cause the largest group of potato dis- 

 eases. Early blight (Alternaria solani) and late blight 

 (Phytophthora infestans) especially the latter, head the 

 list of destructive fungous diseases. Both are diseases 

 of the foliage and stems but late blight also attacks the 

 tubers, causing them to rot either in the field or under 

 improper storage conditions. Fortunately, science has 

 found a specific preventive for these parasites. Spray- 

 ing the plants with Bordeaux mixture will check the 

 ravages of both diseases. In 1885 Millardet, then 

 professor at the University of Bordeaux, published the 

 first directions for preparing Bordeaux mixture, which 

 consisted of certain proportions of water, copper sul- 

 fate, and lime. This mixture has proved of inesti- 

 mable value in the control of some of the most destruc- 

 tive diseases of our food crops. 



The thread-like hyphae of the fungi causing the 

 Fusarium and Verticillium wilts grow in the conducting 

 vessels of the stems and thereby prevent the passage of 

 water through the stems to the leaves. Wilting of the 

 foliage and death of the plant follow. Although the 

 do not cause as much damage as the unchecked 



