PROCEEDINGS 



THE ROYAL IRISH ACADEMY 



PAPERS READ BEFORE THE ACADEMY 



BACTEEIAL DISEASE OF THE POTATO PLANT IN lEELAND 

 AND THE ORGANISM CAUSING IT. 



By GEOEGE H. PETHYBEIDGE, Ph.D., B.Sc, 



Economic Botanist to the Department of Agriculture and' Technical 



Instruction for Ireland, 



AND PAUL A. MUEPHY, Temporary Assistant. 



Plates I.-III. 



Eead December 12, 1910. Published Febkuari 6, 1911. 

 CONTENTS. 



I. Introductory and Historical, 

 II. Characters of the Disease, 



III. Isolation of the Organism, 



IV. Inoculation Experiments, 

 V. Description of the Orgiuiism, 



VI. Pathogenicity towards other Plants, 29 



PAGE 

 1 



9 

 14 

 20 

 23 



VII. Comparison of the Organism with 



allied Organisms, . . .30 

 VIII. Practical Considerations, . . 32 



IX. Summary, Si 



X. Bibliography 35 



XI. Explanation of Plates, . . .37 



I. Inteodugtoky and Histokigal. 



The study of the bacterial diseases of plants is a comparatively young branch 

 of vegetable pathology. Seeing that bacteria play such an important part in 

 the diseases of animals, it is rather remarkable that more attention has not 

 hitherto been devoted to the study of their pathogenic behaviour towards 

 plants. Up to about fifteen years ago, apart from some pioneer work which 

 had been carried on in the United States of America, very little had been 

 done in this direction. Indeed, in some quarters, the opinion was somewhat 



B.I.A. PROC, VOL. XXIX., SECT. B. [A] 



