ROTS 983 



on potato; surface film on bouillon; liquefies gelatin rapidly; coagulates milk; 

 ferments glucose with production of H and COz in the ratio 1:3; indol positive after 

 forty days; methylene blue reduced; ammonia and H 2 S produced from bouillon; 

 enzymes: amylase, oxidase, peroxidase; facultative anaerobe. 



PATHOGENESIS. Pathogenic to orchids grown in the hothouse and 

 also in their habitat. 



METHOD OF INFECTION. The germs enter the leaf tissue chiefly 

 through wounds caused by careless washing. 



CONTROL. Use only a soft sponge soaked in a i : 1000 solution of 

 mercuric chloride for wiping the leaves, and avoid excessive watering 

 as this favors the disease. 



ROT OF CAULIFLOWER AND ALLIED PLANTS 

 Bacillus oleracea Harrison 



HISTORY AND SYMPTOMS. This rot of cauliflower and allied plants 

 was first reported in 1901 from truck gardens in the vicinity of Guelph, 

 Ontario. It is characterized by a soft rot of the roots and a blackening 

 of the stems and leaves. Harrison* has found this condition to be 

 traceable to an actively motile bacillus which invades the intercellular 

 spaces of the plant and destroys the middle lamellae. 



CAUSAL ORGANISM. Bacillus o/eracec^-Harrison is a rod with rounded ends; 

 occurs single or in short chains; measures 2 X o.6/u; motile by means of 7 to 13 

 peritrichate flagella; stains with the ordinary aniline dyes; Gram-negative; in 

 broth heavy turbidity and sediment, no pellicle; stratiform liquefaction of gelatin; 

 on agar spreading, thin, whitish, moist, slightly opalescent; neutral red agar no 

 change in color; litmus milk coagulated, soft curd slowly peptonized; blood serum 

 slightly liquefied; growth positive in Uschinsky's and Fermi's solutions; potato waxy, 

 straw-colored to moist, shining; opt. temp. 30, max. 42, min. 5; thermal death- 

 point 55; facultative anaerobe; slight reduction of nitrates; indol slight; H^S 

 positive; slight gas from glucose and lactose, none from saccharose; acid from 

 sugars; enzymes: proteolytic, diastase, cytase (pectinase). 



METHOD OF INFECTION. Infection takes place chiefly through 

 wounds due either to mechanical or insect injuries. Warm weather 

 combined with excessive moisture appears to favor the spread of the 

 disease. 



* Harrison, F. C., "A Bacterial Disease of Cauliflower (Brassica oleracea) and Allied Plants," 

 Cent. f. Bakt.. Abt. II. Bd. 13, PP- 46, 185, 1904. 



