200 



Bulletin 236. 



7. Preventive Measures. 



It is scarcely necessary to point out that every precaution should be 

 taken to prevent bruises or injuries of any sort, since these make excellent 

 infection courts for the entrance of the bacteria. 



All dead limbs and trees should be promptly removed from the 

 orchard and burned. Old pear trees in the neighborhood of young apple 

 orchards are often a constant source of infection, and, unless kept abso- 

 lutely free of the blight, should be removed. A neighbor careless in 

 respect to blight in his pear trees provides a dangerous source of infection. 



Cut out and burn every trace of twig blight from both pear and 

 apple trees as soon as it is detected. 



Fig. 77. — Pruned stub canker resulting from cutting 



away a waters prout with a knife used shortly before to 

 cut out an active canker and not disinfected. 



When pruning, treat all cut surfaces with the corrosive sublimate or 

 copper sulfate solution and keep them painted until healed. Treat all 

 accidental wounds in the same way. 



Keep the body and main limbs of the tree free of watcrsprouts 

 throughout the summer. 



In planting, choose trees with open or spreading crotches. 



Avoid excessive fertilizing with nitrogenous manures. Apply some 

 form of phosphoric acid to ripen new growths. 



