THE BLACK ROT OF CRUCIFERS : TYPE 147 



rot occurs almost all over Europe and North America, and 

 probably in many other parts of the world. It is said to 

 be common in Japan (Gentaro Yamada) and to occur in the 

 Philippines (Reinking). It was first reported from Europe 

 in 1900 by an American (H. A. Harding). 



Cause. — This disease is due to Bac'erium cainpestre (Pammel) 

 EFS. The organism is a moderately growing, non-viscid, non- 

 capsulate, yellow, non-sporiferous, nitrate-reducing, slowly 



% 



K 



V 



f 





Fig. 82. Fig. 83. 



Fig. 82. — Section of a cabbage leaf-tooth parallel to the surface, showing 

 two water-pores; one empty, the other blocked by bacteria. 



Fig. 83. — Upper stoma of Fig. 82, enlarged to show more distinctly the rods 

 of Bacterium campestre blocking its mouth. 



liquefying, non-gas-forming, casein-precipitating (by a lab fer- 

 ment), aerobic, rod-shaped, or slightly curved or club-shaped 

 schizomycete, motile by means of a polar flagellum (Fig. 88), 

 and forming on the surface of agar-poured plates small circular 

 or slightly irregular, wet-shining colonies (Figs. 89 to 91) which 

 are pale at first but become distinctly yellow (not orange). 

 Filamentous chains occur in sugar-rich media. It resists 

 drying 12 months or more under favorable conditions (Compare 

 with Bacillus tracheiphilus, No. I, and Bacillus carotovorus, 

 No. VI, which from bouillon cultures scarcely resist drying 



