THE BLACK ROT OF CRUCIFERS '. TECHNIC 



153 



immediately under the origin of a leaf ; still others in the paren- 

 chyma of the leaf-blade some at the apex, others on one side 

 midway down. Select leaves several removes from the lowest, 



FIG. 92. Cultures of Bacterium campestre (B), and Bacterium phaseoli (A) in 

 Dunham's solution at end of 4 days. 



otherwise the leaf may be un jointed and thrown off before 

 stem-infection has occurred. 



The plants should be well watered and growing freely for 

 best results, which should begin to be visible in 10 days, more or 

 less, from the time the punctures are made. 



FIG. 93. Sheaf-like tyrosin crystals in a 2-months 12-day old litmus-milk culture 



of Bacterium campestre. X 6. 



For water-pore infections confine young plants in an infec- 

 tion cage in a cool place and spray freely with a water suspension 

 from a 48-hour agar or potato-streak culture. Keep the plants 



