594 BACTERIA IN RELATION TO PLANT DISEASES 



cepted by all phy topathologists, e.g., Smith's and Paine's laboratories, maintain the use 

 of names suggested by Smith in his chapter on "Nomenclature and Classification" in 

 Bacteria in Relation to Plant Diseases, "^ in which the generic name Aplanobacter was 

 substituted for Bacterium (Migula) ; Bacterium for Pseudomonas (Migula) ; and Bacil- 

 lus (Migula) was retained. Stevens' attempted to return to Migula's system. Ac- 

 cording to the system proposed in Bergey's Manual, the tribe Erwiniae includes all 

 plant pathogens, the forms with peritrichous flagella falling into the genus Erwinia, 

 while the forms with polar or no flagella constitute the genus Phytomonas. Eleven 

 of the listed forms belong to Erwinia and 36 to Phytomonas. 



SEROLOGICAL METHODS IN IDENTIFYING AND DIFFERENTIATING PLANT PATHOGENS 



Uncertainty has existed among phytopathologists as to whether many of the 

 so-called species really deserve such rank, or should be considered subspecies or vari- 

 eties. In some quarters the attempt to delimit species has been considered futile, 

 and the application of more refined methods in an attempt to differentiate species a 

 senseless waste of effort and time. 



Host specificity or association of a pathogen with a definite symptom complex, has 

 been used extensively or even solely to differentiate and diagnose species whenever 

 cultural characters have been unsuited. The situation is becoming steadily more com- 

 plicated because detailed studies indicate that supposedly well-established and clear- 

 cut species may be complexes or aggregates of forms. 



Relatively little use has been made by phytopathologists of serological methods 

 in wrestling with the problems of diagnosis and differentiation of plant pathogens. 

 The method has however been used very extensively and. successfully in classifying 

 the organisms causing the nodules of legumes. This work, however, done by soil bac- 

 teriologists, has gone largely unheeded by phytopathologists. Do'dge,^ Jensen, ^ Paine 

 and Lacey,5 Brooks, Nain, and Rhodes,** Takimato,^ and Goldsworthy,^ had varying 

 success in applying the agglutination test to grouping, identification or differentiation 

 of plant pathogens. Link and Sharp,'^ Sharp,'" and Link and Link,'' working primarily 

 with a group of yellow schizomycetes which are pathogenic to plants and which are 



I Smith, E. F.: op. clL, 1, 154-77. 



^Stevens, F. L.: Plant Diseise Fungi. New York: Macmillan, 1925. 



3Doidge, Ethel: "A Bacterial Spot of Citrus," Ann. Appl. Biol. 3, 53-83. 1917. 



4 Jensen, C. O.: "Undersogelser vedrorende nogle svulstlignende Dannelscr hos Planter," Kgl. 

 Vctcrinaer-og Landbohojskoles Aarsskrift. Copenhagen, 1918. 



5 Paine, S., and Lacey, M.: "Studies in Bacteriosis," Ann. Appl. Biol. 10, 204-9. 1923- 



* Brooks, R. St. John, Nain, K., and Rhodes, Mabel: "The Investigation of Phytopathogenic 

 Bacteria, by Serological Methods." Jour. Path, and Bad., 28, 203-9. 1925. 



7 Takimato, S.: "Studies on the Putrefaction of Vegetables," /. PI. Prol., 8, 344-53. 1921. 

 (Japanese) Bot. Absl., 14, 600. 1925. 



8 Goklsworthy, M. C: "Studies on tlic Spot Disease of Caulillower; a Use of Serum Diagnosis," 

 Phylopath., 16, 877-83. i92(). 



'Link, George K. K., and Slnup, C. (I.: "Correlation of Host and Serological Specificity of 

 Bad. campestre, Bad. jUiccunifarieii.s, Bad. pliaseoli, and Bad. pliaseoli .snjensc," Bot. Gaz., 83, 145- 

 60. 1927. 



'» Sharp, C. G.: "Virulence, Serological, and Other Physiological Studies of Bad. flaccunifaciens, 

 Bad. plia.seoli, and Bad. pliaseoli sojcnse," ibid., f)p. 113-44. 1927. 



" Link, George K. K., and A. DeS.: //)/(/., 85. 1928 



