134 



BACTERIAL DISEASES OF PLANTS 



FIG. 65. Portion of a cucumber leaf wilted by Bacillus tracheiphilus (which 

 was abundant in many of the smaller veins) and then greedily gnawed by the 

 striped cucumber beetle (Diabrotica vittata). Such bet-tics are then infectious to 

 other plants. 



FIG. 66. A healthy cucumber leaf slightly gnawed by an infected striped beetle 

 and developing the bacterial wilt around the bitten places. From a field near 

 Washington, 1893. 



