CHAPTER II. 



GALLS AND TUMORS. 



CROWN GALL. 

 Bacterium tumefaciens Erw. Smith and Townsend. 



Crown gall is one of the most recent diseases to be traced to bacterial 

 origin. Its occurrence is so common in nursery stock that in a certain 

 western state seventy-five per cent of the young trees and shrubs con- 

 demned by nursery inspectors are condemned for crown gall, and 

 Tourney places the annual loss to orchardists at $500,000 to $1,000,000. 



FIG. 93. Crown gall with hairy root on nursery stock. Northern Spy apple. (After 



Paddock.} 



One of the remarkable things about this disease is the large number of 

 families which are subject to the infection. This list includes apple,* 

 peach, pear, plum, prune, apricot, cherry, grape, raspberry j black- 

 berry, rose, English walnut, chestnut, almond, white poplar, hop, sugar 

 beet potato, tomato, tobacco and Paris daisy. 



SYMPTOMS. The swellings or galls, small at first, usually "appear 



* Both hard gall and hairy root. 



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