Blight Canker of the Apple Tree. 



191 



while twigs and blossoms punctured with a sterile needle gave no infection. 

 This last experiment was twice repeated during the summer with pure 

 cultures of the bacteria from the apple tree canker. The blight resulted 

 in practically every case. Young fruits of both the pear and apple were 

 also inoculated and gave well developed cases of the disease. (Fig. 70.) 



Fig. 63. — Badly cankered trees showing the dead leaves clinging to the branches. 



By a comparative study in various culture media of the bacteria from 

 cankers, twigs and fruits of both pear and apple (Fig. 71) secured from 

 different orchards about Ithaca, the organism of the canker was shown to 

 be identical with that of the well known " fire blight " of the pear and 

 " twig blight " of the apple. 



