278 POMOLOGY 



ference in the growth and time of flowering of whitened and 

 unwhitened peach trees." 



247. Securing hardier fruits. — A discussion of breeding 

 hardier fruits is included in the general subject of breeding 

 (Chapter XIII), but a statement in regard to the acclimati- 

 zation of plants is apropos at this point. There is a lack of 

 unity of opinion on this point, although it has been discussed 

 for many years a,nd many observations have been recorded. 

 It seems unlikely that individuals of a tender species will 

 manifest any permanent character for hardiness when such 

 plants are removed to a colder climate. While an occasional 

 individual may be more resistant to cold than its companions 

 of the same origin, the enviromnent may be different or some 

 other cause operating which would not be permanent. To at- 

 tempt to select biotypes showing this hardy character would 

 be a slow process with the weight of evidence against its suc- 

 cess. The better procedure to follow would be to breed such 

 tender species with hardy "relatives" and select individuals 

 exhibiting the desirable qualities of both parents. Hence it 

 is practically useless to attempt to find a particularly hardy 

 Baldwin apple or Crawford peach tree from which to prop- 

 agate a strain that will withstand the northern winters where 

 these varieties are unreliable. 



248. Treatment of frozen trees. — Great care must be 

 exercised in treating trees which have been frozen or the 

 injury may be extended rather than reduced. As indicated 

 previously, the pruning given winter-injured trees calls for 

 moderation and the operation should not be hastened but 

 rather delayed until the probable injury can be determined. 

 Some seasons the peach is so injured that the buds are de- 

 layed in starting; this calls for careful observation lest live 

 wood be cut away and the tree umiecessarily reduced. 



In addition to proper pruning, it is also advantageous to 

 apply a quickly available form of nitrogen, such as nitrate 



