WILT-DISEASES OP TOBACCO. 267 



flatter; on potato the colonies become rapidly confluent, forming a creamy, pale yellowish-white mass, 

 which is distinguishable from the substratum only by its shining appearance. 



" I have been able to obtain several artificial infections by lacerating the collar and rubbing the 

 wound with a culture of the first generation of the bacteria, obtained pure with the greatest ease, by 

 sowing some of the diseased tissue. " 



This disease is said to be confined to the collar, to be quite rare, and to require wet 

 soil for its development. 



Bacillus putrifaciens putridus is said to be a cylindrical rod with rounded ends, in short chains 

 of two or three elements when young; 0.5 to 0.7 X 1.2 to 1.8/1; it is closely related to his B. ceruginosus ;* 

 bouillon, gelatin, etc., are stained uranium green. The bouillon is very lightly clouded, without much 

 surface pellicle, and with a white precipitate. Gelatin is not liquefied; on agar or gelatin the colonies 

 are small, shining, irregular, opaque, white with a very faint rose color. 



Inoculation experiments appear to have been scanty and unsatisfactory. Under bell-jars, in a 

 humid atmosphere, about one-third of the inoculations showed some effect. No details are given. 

 The lesions were less profound than those in the field. 



A collar-rot of tobacco occurs in the United States. Specimens were received in 19 12 

 from Elmira, New York. The bark is killed between root and stem and the plants wilt. 

 Bacteria are present. Poured plates yielded green-fluorescent and white organisms. The 

 writer knows nothing respecting their cultural characters or pathogenicity. A tobacco 

 canker has also been reported from Connecticut by Clinton. 



THE INDIAN DISEASE. 



Hutchinson has recently published a paper on an Indian disease resembling the Gran- 

 ville tobacco wilt. Unfortunately, it was received too late for more than a very brief 

 abstract. 



The disease occurs annually in the Rangpur district in Bengal in northeastern India, and has 

 been present for many years. In the field it is patchy in its distribution. The loss is usually not 

 more than 5 or 6 per cent, but sometimes 20 to 25 per cent. Growers generally consider it to be a 

 disease of moist soils and its local name is "Rasa" or moisture-disease. It is attributed to Bad. 

 solanacearum Smith, which is said to be non-motile (numerous observations covering a period of 

 more than two years), but accompanied almost invariably by a morphologically similar motile form 

 which produces on potato only a yellow pigment (yellow ocher with a greenish tinge), and is not 

 pathogenic. The true parasite measures 0.6 by 1 .0 to 1.5/1; on agar it is white, moist, and smooth, 

 becoming sepia brown with stain of the substratum; on gelatin the colonies are round, thin, white, 

 opalescent, brown under magnification by transmitted light, and without liquefaction; bouillon is 

 turbid on shaking and alkaline in reaction (a good distinguishing trait) ; on potato the growth is 

 watery and colorless at first, then opaque white, becoming brown, and finally bitumen black; in 

 glucose bouillon no acid or gas is formed. In mixed cultures Bad. solanacearum may be distinguished 

 by its tendency to show bipolar staining with methylene blue. This is a common phenomenon on 

 potato cultures. f Successful inoculations were obtained on tobacco and tomato by needle-punctures. 

 Soil inoculations generally failed unless the roots were injured. Marked differences in virulence 

 were observed in cultures, also in their brown pigmentation and a non-pigmented strain was observed. 

 Variations in morphological character and in virulence are attributed to the culture medium used. 

 Promptest results were had from potato-culture inoculations, slowest from bouillon ; agar was mid- 

 way in point of time. When mixed with saprophytes, such as Bad. megatherium and Bad. prodigiosus, 

 inoculations often failed. " It was found that a mixed culture of Bad. solanacearum and Bad. prodi- 

 giosus in bouillon depended for its pathogenicity upon a preponderance of the former in the medium 

 sufficient to produce alkalinity." The wilting of the plant is ascribed to the action of bacterial 

 toxins rather than to mechanical plugging of the vessels. This hypothesis is supported by interesting 

 experiments, i. e., (1) a healthy tobacco plant may be cut half through the stem without causing wilt 

 even in the leaves immediately above the cut; (2) an alcohol precipitate from a bouillon culture when 



* Bacillus ceruginosus Schroter is earlier (1886), and consequently Delacroix's name should be rejected, and in the 

 present stage of our knowledge of the disease it is scarcely worth while to suggest a substitute. Griffon states that 

 Bacillus brassiccevorus Delacroix and Bacillus aeruginosas Delacroix are nothing but B. fluorescein putrid us; while Bacillus 

 caulivorus Prill, and Delacroix is B. fluorescens liquefaciens. It is with a sigh of relief that one reads: "II n'y a plus 

 lieu de conserver les denominations specifique de caulivorus, brassicavorus et ceruginosus." 



fThe Florida potato organism (1914) grown on cooked potato, also showed bipolar staining with methylene blue. 

 See also Honing's statement (p. 253). 



