WHEN TO PRUNE 103 



vantage to the healing process ; and the check- 

 ing of the stnb from its longer exposure is also 

 to be considered. 



On the other hand, pruning in the growing 

 season of spring exposes the plant to bleeding. 

 It is not germane to the present discussion to 

 consider the effect of this bleeding on the plant, 

 although it may be said that injury rarely fol- 

 lows. It is said, however, that the sap sours 

 upon exposure to the air and injures the bark 

 and cambium about the edges of the wound. 

 Although this is a very common notion, I have 

 looked in vain for a number of years for a 

 single confirmation of it. Fruit trees rarely 

 bleed to any extent, and on trees which do 

 bleed, it is doubtful if this injury follows. The 

 Japanese walnut bleeds profusely. On the 10th 

 of April, 1896, I cut a limb two inches in 

 diameter from one of these trees. The sap ran 

 freely, and kept the bark wet for two weeks for 

 a distance of nearly two feet below the cut. At 

 this writing (Jan. 15, 1898) the wound looks as 

 shown in Fig. 88. It is healing well on all 

 sides, and there has never been the least injury 

 from the bleeding. Moist wounds, however, do not 

 allow of the efficient application of dressings. 



Let us now go to the trees. In the fall of 

 1891, experiments were begun at Cornell to 

 determine the best season for the making of 

 wounds and the best dressings for covering 



