OTHER BACTERIAL DISEASES. 389 



Bidb Rot of Hyacinth. This disease especially attacks the 

 bulb of this plant, causing it to rot and decay. It is produced 

 by bacteria, as has been demonstrated successfully. One of 

 the common forms is caused by an organism named B. hya- 

 cinthi, while another type of the disease, with different symp- 

 toms, is caused by another organism named B. hyacinthus 

 scpticus. The diseases attack both the leaves and the bulb, 

 but are especially characterized by a decay 

 of the bulb. 



Curcurbit Wilt. This is one of the best * *>\ 



known and most thoroughly attested of *fr J f ( 



bacterial diseases of plants. It is espe- x ^ ^ 



cially common in the tomato and causes a ty ^$ ^ ^^ 

 rapid wilting of the plant and its final /' // * 

 complete destruction. It has been care- v % 'vT^^t*\ 

 fully studied by several bacteriologists and 

 found to be due to a bacillus which has 

 been named B. trachciphilus. (Fig. 40.) 

 The bacillus can be cultivated readily in B.tracheiphiius. Caus- 



^ ing the curcurbit wilt. The 



the laboratory. If healthy plants are in- two lower 



res are more 



oculated by pricks from needles that have 



' r flagella. (&*/*.) 



been dipped into the bacteria culture, the 

 inoculation is inevitably followed by the wilting and the 

 browning of the plant, and the extension of the disease with 

 the typical symptoms, the plant tissues becoming filled with 

 bacteria in great quantities. 



Black Rot of Cabbages. This disease attacks not only the 

 cabbage, but other cruciferous plants, such as the rutabaga, 

 turnip and cauliflower. It is characterized by a blackening of 

 the leaves, which extends until eventually it may ruin the 

 plant. It is quite common in America and produces not a 

 little loss from our gardens. It has also recently been shown 

 to be abundant throughout Europe. The cause of the disease 

 is a bacterium called Bacillus (or Pseudomonas) campcstris. 



