April 21, 1922] 



SCIENCE 



433 



but the absence of the latter is atoned for by 

 the presence of a table of contents just before 

 the introduction. As in most of Dr. Mortensen's 

 publications the illustrations are all that could 

 be desired and are of the greatest service to 

 the user of the book, while the text is entirely- 

 free from ambiguities and shows the customary 

 positiveness of the writer. The whole appear- 

 ance of text and plates is admirable and the 

 Carlsberg Fund, no less than the author, is to 

 be congratulated ou this very important con- 

 tribution to our knowledge of eehinoderms. 

 HuBEBT Ltman Clark 



SPECIAL ARTICLES 



A BACTERIAL WILT OF THE BEAN CAUSED 



BY BACTERIUM FLACCUMFACIENS 



NOV. SP. 



A NEW bacterial disease of navy beans has 

 appeared in South Dakota. The grower on 

 whose farm the disease was discovered reports 

 that what he believes to be the same disease 

 killed 90 per cent, of his 1920 crop. In 1921 

 he planted the seed harvested from the remain- 

 der and lost about 25 per cent, of his crop. 

 Some of this 1920 Dakota seed planted at Ar- 

 lington, Virginia, also produced a large pro- 

 portion of diseased plants, many of which 

 never survived the seedling stage. The dis- 

 ease is characterized by a wilting of the leaves 

 of seedlings sometimes accompanied by a dis- 

 coloration, and by dwarfing, reduction of yield 

 and the death of some of the shoots, if the 

 plant survives the early stages of growth. 



Plants from South Dakota, received in the 

 Laboratory of Plant Pathology, Bureau of 

 Plant Industry, August 6, 1921, were found to 

 contain bacteria in the vessels of the stem 

 often accompanied by a browning of the vas- 

 cular ring. The writer suspected the presence 

 of Bacterium solaiiacearum Erw. Sm. but when 

 petri dish poured-plates were made from the 

 diseased stems a yellow organism was isolated. 

 This, when pricked into vigorously growing 

 King of the Mountain bean seedlings produced 

 the wilt in every case. From these infected 

 plants the yellow organism has been reisolated 

 and has produced the wilt in Great Northern 



beans. King of the Garden lima and Ito San 

 soy-beans have also become infected as the re- 

 sult of pure culture inoculations. 



The same organism has been isolated from 

 the Arlington, Virginia, plants and with it the 

 writer has reproduced the disease. 



The discoloration mentioned above may con- 

 sist of a dull green or brownish green, green- 

 ish brown or reddish brown area sometimes 

 bordered with yellow. The discolored area is 

 flabby at first and later dry and papery. In 

 many oases the whole leaf blade and petiole 

 become flabby and droop without any dis- 

 coloration at all, whereas in others a portion 

 of the leaf becomes flabby and discolored while 

 the rest of the blade and the petiole isi turgid 

 for a time at least. It is presumably a question 

 of the number of vessels plugged by the bac- 

 teria. This same phenomenon has occasionally 

 been observed in secondary infections of young 

 leaves by Bacterium phaseoli. 



The wilt of the seedlings in some respects 

 suggests the "systemic disease" of beans 

 ascribed by Burkholder to Bacterium phaseoU 

 but the parasite under consideration is very dif- 

 ferent from Bacterium phaseoli. For example, 

 its very moderate, often scanty growth on potato 

 cylinders, due to its very slight diastasic action, 

 is in marked contrast to the exceedingly 

 copious prolonged growth and marked diastasic 

 action of Bacterium phaseoli Erw. Sm. The 

 color on potato is Ridgway's mustard or pri- 

 muline yellow (Color Standards and Nomen- 

 clature, plate XVI, 2nd ed., 1912) and there 

 is usually a marked graying of the potato. The 

 difference in the colonies are less marked but 

 plates of the two organisms when compared 

 are easily distinguishable. The colonies of 

 Bacterium phaseoli are much more wet-shining 

 and of a much more syrupy consistency. Both 

 Bacterium phaseoli and the South Dakota or- 

 ganism reduce the litmus in litmus milk in 4 

 to 7 days but the cultures of the latter flnally 

 become acid and the tehavior of the two or- 

 ganisms is very different in regard to the man- 

 ner and time of the other changes taking place 

 in the milk. Cultures of Bacterium phaseoU 

 begin to clear in 1 to 6 days, and a very soft 

 mobile curd is formed, a partial peptonization 



