THE POTATO 195 



the soil quicker than will manuring and cultivated 

 crops. 



'*17. Longer than a three-year potato rotation 

 should be practised. 



" 18. Storage htter and sick seed should not be 

 allowed to reach the manure pile, as this will be a 

 sure method of distributing the disease and infect- 

 ing the fields. 



"19. The disease demands further study. The 

 Department of Botany invites cooperation with 

 potato growers. Examination of seed potatoes 

 and plants will be made and the results reported. 



"This Department, in cooperation with the Bu- 

 reau of Plant Industry of the U. S. Department of 

 Agriculture, has the franking privilege on diseased 

 plant material; the franks will be sent to those hav- 

 ing diseased material to be forwarded. " 



Prof. B. O. Longyear of the Department of Bot- 

 any and Forestry of the Colorado Agricultural Col- 

 lege says: 



"One of the most widespread and common 

 diseases of the potato caused by fungi is that com- 

 monly known as the Fusarium disease, or Fusarium 

 blight. This trouble first manifests itself in the 

 field by the wilting and yellowing of the lower 

 leaves of plants that have reached the height of 

 ten to twelve inches. In bad cases the entire 

 foliage appears to suffer as though the plant were 

 not getting suflScient moisture. Later on, the tips 

 of the leaves turn brown and dry up, leading to 

 the trouble commonly known as tip burn. The 

 edges of the leaves commonly roll inward during 

 the heat of the day, although they may partially 

 revive during the night. 



