Street Trees. 



331 



cuts the period of healing ma}'' occupy two, three or more years (see 

 Fig. 250). During this heahng period protection must be given to the 

 surface to keep out all moisture and prevent evaporation and subse- 

 quent dr\dng of the' dead inner -wood. If this is not done, the spores 

 of fungi enter and help to decay the exposed area. 



Protection is necessary on all large wounds (more than lY' in diameter), 

 and on all smaller wounds that are the result of fall and early winter 

 pruning. As soon as the wounds are made, some substance should be 

 applied to the surface which will serve as an antiseptic and also as a 

 preventive against evaporation and water. Bordeaux mixture may be 

 applied as an antiseptic, if desired; but it is not permanent as a covering 

 against evaporation. Tar 

 and lead paint are the best 

 mixtures for this work, 

 the latter being preferred 

 by the majority of pro- 

 fessional pruners. Dress- 

 ings used on fresh wounds 

 of pruned trees should in 

 all cases be preservative 

 and preventive, and in no 

 case should they be such as 

 might injure the tissues. 



Protective substances 

 are applied in a thick 

 layer, and one covering 

 is generally sufficient for 

 small wounds; for large 

 wounds a second coat is 

 put on during the second 



or third year, and if several years are required for the healing, the 

 surface should receive attention each year in order to avoid any 

 chance of decay. A common practice is to cover ver)^ large wounds 

 with dressing, and over the whole place a covering of tar paper which 

 will ser\^e to increase the efficiency of the dressing. Tar is not much 

 in favor as a dressing among professional operators as compared with 

 white lead, which is more permanent and less repulsive to the eye. 

 However, tar possesses the advantage that, when applied hot, it strikes 

 into the wood, thus making it a most desirable dressing to be used on 

 the wounds of maple trees during the spring months when paint will 

 not adhere. 



Fig. 252. 



-A well filled cavity preserves the tree 

 against further decay. 



