512 MICROBIAL DISEASES OF PLANTS. 



Bacillus carotovorus is a wound parasite which invades the inter- 

 cellular spaces, dissolving the middle lamellae and portions of the inner 

 lamellae, thereby establishing a condition which is known as a soft rot. 

 Jones* has shown this solution to be due to a bacterial enzyme which he 

 has named pectinase. 



CAUSAL OGRANISM. The organism is a variable rod, majority 2.0/4 by 0.8/4, 

 rounded ends, motile by 2 to 10 peritrichiate flagella; no endospores; no capsules; 

 slight pseudozoogloea. Stains readily with aqueous stains. Gram-negative. 



On agar. growth abundant, filiform to spreading, glistening, smooth, white, opaque 

 to opalescent. Potato glistening, white, decided odor, smooth, butyrous, medium 

 grayed. Gelatin stab filiform, liquefaction crateriform to infundibuliform, liquefac- 

 tion begins second day and complete in six days. Broth 'thin pellicle, clouding, 

 abundant, sediment. Milk coagulated, slowly peptonized, rendered acid, litmus 

 reduced. Cohn's solution no growth. Uschinsky's solution abundant growth. 

 Quick tests; soft rot of uncooked carrots, turnips, cabbages. Slight gas produced from 

 dextrose, lactose, saccharose but not glycerin. Acid from dextrose, lactose, saccharose 

 and glycerin. Nitrates reduced. Slight indol. Thermal death-point, 48 to 50; 

 grows at 37. Optimum temperature 25 to 30. Pathogenic to the roots of carrot, 

 turnip, rutabaga, radish, salsify, parsnip, bulb of onion, leaf stalk of celery, leaves and 

 scapes of hyacinth, cabbage, cauliflower, lettuce, Irish potato, fruit of tomato, eggplant 

 and pepper. 



B. oleracece Harrison, and B. omni-vorus van Hall, formerly described as bacterial 

 species capable of producing soft rots, have been reported by Harding and Morse')' 

 as identical with B. carotovorus and therefore to be recognized no longer as distinct 

 species. 



CONTROL. Jones believes that the soft rots can be practically held 

 in check by rotation of crops; by not using manure into which garden 

 refuse has been thrown; by drying the surface of the roots thoroughly 

 and exposing them to bright sunshine before storage; by maintaining a 

 constant low temperature (4) during storage. 



SOFT ROT OF HYACINTH. 

 Bacillus hyacinthi septicus Heinz. % 



A very active soft rot of the hyacinth bulb, producing a bad smelling, 

 slimy condition in a few days, has been described by Heinz as caused by 

 an unpigmented, motile bacillus. 



* Jones, L. R., "Pectinase, the Cytolytic Enzyme produced by Bacillus carotovorus and 

 certain other soft rot organisms." Tech. Bull, n, New York Agr. Exp. Sta., 1909. 

 f Harding and Morse, Tech. Bull, n, New York Exp. Sta., 1909. 

 J Heinz, Cent. f. Bakt., 5, p. 535, 1899. 



