CROWN-GALL OF APPLE AND PEACH 

 WITH NOTES ON THE BIOLOGY 

 OF BACTERIUM TUMEFACIENS 



Donald Reddick and V. B. Stewart 



THE CROWN-GALL DISEASE 



The crown-gall disease, caused by Bacterium tumefaciens Smith & 

 Townsend,^ occurs on a great variety of plants and over a wide geo- 

 graphical range. It has been noted particularly in fruit culture from 

 practically every fruit district in the United States, and the very general 

 opinion expressed in the literature on this subject is that the disease is a 

 dangerous one and its introduction into a planting is greatly to be feared. 



The evidence bearing on the economic importance of the disease is 

 largely observational and few experimental data are at hand to show its 

 exact importance. The observational data are fully summarized by 

 Smith, Brown, and Townsend ^ and need not be repeated here. In 

 general, it may be concluded from these authors' digest of the literature 

 that apples are not seriously affected but that peaches and many other 

 plants are. These writers are inclined, however, to include apples (page 

 197 of the bulletin cited) in the list of plants that should be inspected 

 for crown-gall, and to recommend rejection of trees showing galls or 

 hairy root. They suggest that even if apple trees are not materially 

 affected by crown-gall, the distribution of trees bearing galls will serve 

 to spread the disease to new localities and to other hosts which are more 

 susceptible and which may be injured thereby. Neither point seems to 

 be well taken when one considers (1) the very wide distribution of the 

 disease at the present time, and (2) that the apple constitutes a relatively 

 permanent crop which is not interplanted except for a few years and 

 then preferably with cultivated crops such as potatoes, beans, corn, 

 and the like, that is, plants which do not develop the disease under natural 

 conditions. 



In a more recent publication, Erwin F. Smith ^ states that ''when 

 death results it is not due to the direct action of the bacteria, but to 



^Attention is called to the fact that this organism is named Bacterium tumefaciens in conformity with 

 the nomenclature of Erwin Smith, which is in common iise among plant pathologists. According to the 

 nomenclature commonly followed by bacteriologists, however (see Bergey'a Manual oj Determinative 

 Bacteriology, 1923), this organism would be called Phytomonas tumefaciens. 



' Smith, Erwin F., Brown, NeUie A., and Townsend, C. O. Crown-gall of plants: its cause and remedy. 

 U. S. Dept. Agr., Bur. Plant Ind. Bui. 213:1-215. 1911. 



• Smith, Erwin F. Further evidence that crown gall of plants is cancer. Science 43:871-889. 1916. 

 (The quotation cited is on page 876.) 



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