352 



Thf Principles of Fruit -growing. 



the open in regions where the ground freezes 

 deep. This subject of the root-galls has been 

 fully gone over by various writers, and a summary 

 of the subject is presented in Bulletin 117 of the 

 Cornell Experiment Station (although this subject is 

 by no means well understood), from which the fol- 

 lowing epitome is clipped: "The conclusion of the 

 whole matter, then, as we now 

 understand it, is that these root- 

 galls are not the work of a par- 

 asite, but are a mal- forma- 

 tion following some injury of 

 the root, or some uncongenial 

 condition in soil or treatment. 

 The galls may seriously interfere 

 xv ith the nutrition of the plant, 

 ' u mail J' cases causing it to be- 

 come weak and sickly. It is 

 probable that the trouble is not 

 communicable, and that cutting 

 off the gall averts further trouble 

 from that source. As a precau- 

 tionary measure, however, we 



much prefer to plant only trees with perfectly clean 

 and normal roots." 



The injuries caused by hail are very often con- 

 founded with those wrought by borers and other 

 pests, and it is the delight of many persons to en- 

 deavor to puzzle the experimenters and teachers with 

 sppcimens of such work. Plum limbs injured by 

 hail-stones are shown natuial size in Fig. 65. 



Pig. 65. 



Injuries by haiJ- 



stones. 



