

A CONSPECTUS OF BACTERIAL DISEASES OF 



PLANTS 



ERWIN F. SMITH 

 U. S. Department of Agriculture, Washington, D. C 



1 



All our knowledge of these diseases has come within a gen- 

 eration. It began thirty-six years ago with the announcement 

 of the bacterial origin of pear blight by Professor T. J. Bur- 

 rill of the University of Illinois, who is with us to-day. During 

 the first half of that period progress was slow and doubt uni- 

 versal, especially in Europe. 



It is now eighteen years since I ventured the statement, 

 that " there are in all probability as many bacterial diseases 

 of plants as of animals. ' ' This statement was received with 

 much skepticism, not to mention active opposition, but time 

 has more than borne out my statement, and there is now no 

 one left to dispute it. To-day I will venture another, and 

 broader generalization, to wit : It appears likely that event- 

 ually a bacterial disease will be found in every family of 

 plants, from lowest to highest. This prediction is based on 

 the fact that although the field is still a very new one, with 

 no workers in most parts of the world, such diseases have been 

 reported from every continent, and are already known to occur 

 in plants of one hundred and forty genera distributed through 

 more than fifty families. 



DISTRIBUTION 



Following Engler's arrangement, I will list these families 



that you may 



how wide is the distribution of bacterial 



diseases in plants and how utterly wrong were those who said 

 that there were no such diseases, and also those who conceded 

 a little but said that they were very rare and restricted to the 

 soft underground parts of a few bulbous and tuberous plants, 

 and generally preceded by fungi. 



In this list, I have included 



ly the flowering plants, but some of the cryptogams 



1 Am. Nat. 30: p. 627. 1896. 

 Ann. Mo. Bot. Gard., Vol. 2, 1915 



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