154 



BACTERIAL DISEASES OF PLANTS 



in the cages in moist air for 30 hours and water freely. Examine 

 the plants morning, noon and evening, and if the leaves look dry 

 atomize sterile water on them and flood the soil around the 



FIG. 94. Cross-section of a cauliflower stem showing a cavity in a small bundle 



occupied by Bacterium campestrc. 



cages. Examine the leaf serra- 

 tures at least once every 3 days 

 until signs appear. 



Try soil infections through 

 broken roots: a, on very young 

 plants; 6, on plants having stems 

 Y to ^ inch in diameter. What 

 do you conclude? 



Determine 



FOR THE ORGANISM. Mor- 



phology. Size in microns, form 

 (straight rods, curved rods, club- 

 shaped rods), aggregation of 

 elements, i.e., chains, filaments, 

 etc., motility on margin of 

 hanging drop, absence of endo- 

 spores, presence and distribu- 

 tion of flagella (Loffler's stain). 

 Is there ever more than one 



flagellum? Try Gram's stain. Look for involution forms. 



Use various media. Try cultures of different ages. 





FIG. 95. Longitudinal section of 

 a cauliflower bundle, similar to Fig. 

 94, showing entire disorganization due 

 to Bacterium, campestre. 



