Minnesota Plant Diseases. 34 i 



Rotation of crops has been suggested to prevent a recur- 

 rence of the disease. 



Wilt of cucurbits (Bacillus tracheiphilus Sm.). Squash, 

 muskmelons, cucumbers and their relatives are attacked. The 

 existence of this disease has not yet been reported from Min- 

 nesota but is well known in eastern states. The disease is 

 caused by bacteria which gain entrance chiefly through wounds 

 in the stem or leaf. These wounds are often caused by insects. 

 The bacteria immediately seek out the water-conducting tis- 

 sues and settle there in such great numbers that the flow of 



FIG. 173. Bacterial wilt of squash. After Clinton. 



water is impeded. The result is a wilting of the plants and 

 death usually follows. This disease is of interest, in that it 

 shows an unhealthy condition in the host plant, induced not 

 by a directly destructive action of the disease-causing organ- 

 ism, but by the interference with the normal life processes ol 

 the plant, i. e., the obstruction of the water-conduction current. 

 The sprays which are used for downy mildew and anthrac- 

 nose of cucurbits will prevent this disease. Rotation of crops 



