SCHIZOMYCETES. BACTERIA 



133 



XIII. SOFT ROT OF THE CALLA 



Bacillus aroidece Townsend 



Townsend, C. O. A Soft Rot of the Calla Lily. U. S. Dept. Agl., Bureau 

 Plant Industry, Built. 60 : 1-44. pis. i-q. 1904. 



This organism, very closely related to the preceding, has been 

 found to be the cause of a serious soft rot of the calla lily, 

 destroying the plants at about the time of flowering. The seat 



Fig. 39. Isolation Culture of Bacillus arowea- Townsend. 

 (Photograph by C. O. Townsend) 



of the disease is principally in the corms, petioles, and flower 

 stalks. If inoculated into a wound, the bacillus will produce a 

 rot in many raw vegetables, and also in some green fruits. The 

 cultural characters have been indicated. According to Town- 

 send it produces on agar very characteristic radiate colonies 

 (Figs. 38, 39) at or near the optimum temperature. The rot 

 in the calla may be prevented by a careful selection of the corms 

 and by changing the soil in the beds every three or four years. 



