624 MICROBIAL DISEASES OF PLANTS 



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 Organism. — The organism is a variable rod, majority 2.0/4 by o.ip., 

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

 slight pseudozoogloese. 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 infundi- 

 buliform, liquefaction 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 solu- 

 tion — abundant growth. Quick tests; soft rot of uncooked carrots, turnips, cab- 

 bages. Slight gas produced from dextrose, lactose, saccharose, but not glycerin. 

 Acid from dextrpse, 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, cauli- 

 flower, lettuce, Irish potato, fruit of tomato, eggplant and pepper. 



B. oleracetB Harrison, and B. omnivorus van Hall, formerly described as bacterial 

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

 as identical with B. carotovorus and therefore to be recognised 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 — ^HeinzJ 



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, ii, New York Agr. Exp. Sta., 1909. 

 t Harding and Morse, Tech, Bull. 11, New York Exp. Sta., 1909. 

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



