THE POTATO 177 



THE LATE BLIGHT 



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The Late Blight (Phytophthora infestans) is a 

 very serious disease. The following is from "Bul- 

 letin 71" of the Wyoming Experiment Station: 



"Though this disease had not been fully worked 

 out until in comparatively recent times, yet there 

 are references in literature to potato epidemics 

 which devastated the fields of Europe at intervals 

 during the nineteenth century, which were undoubt- 

 edly due to it. The first recognizable description 

 occurs first in 1845. Its life history, however, has 

 now been known for some time, though as late as 

 the '80's and '90's this trouble was still confused 

 with the early blight. For a considerable time it 

 was not known that the rot which usually follows 

 an attack is also due to the same parasite. While 

 probably of rare occurrence in the Rocky Moun- 

 tain states, late blight is feared more than any 

 other disease in the potato districts of the Eastern 

 States. It is estimated that the loss in New York 

 alone sometimes amounts to $10,000,000 a year. 



" Though this fungus resembles the early blight 

 in many respects, yet it is easily distinguished 

 from it by its mode of growth, the effect it pro- 

 duces on the leaf tissues, and especially by the 

 spores and the way in which they are produced. 

 It finds entrance into the potato leaf through the 

 stomata, and the mycelium once having found 

 entrance spreads by numerous branching hyphse 

 through the leaf among its cells, from which the 

 fungus draws its nourishment. After the leaf 

 has become filled, as it were, with the mycelium, 

 the fruiting period of the fungus is reached. Some 

 of the hyphse then grow out through the stomata, 



