422 



BACTERIAL DISEASES OF PLANTS 



FIG. 321. Crown gall on sugar-beets due to Bacterium tumefaciens. Pure- 

 culture, needle-prick inoculations, using organism isolated from a tumor on hop. 

 Time, 104 days. Necrosis has begun. Tumors larger than the roots. Actual 

 diameter about 4 inches. 



