DRESSINGS FOR WOUNDS 



159 



few weeks or even a year. This material is often referred to as 

 coal tar. Certain forms of thin or very fluid character used for 

 roof coverings and as metal paints are not well adapted for use as 

 wound dressings. 



In general, pruning wounds less than one and a half inches in 

 diameter scarcely require a covering. There may be cases, how- 

 ever, where heavy pruning is practiced, in which more general treat- 

 ment of the wounds is advisable. Solid asphaltum has not proved 

 successful as a wound covering. It may be rendered fluid as de- 

 tailed below (142). 



133. Effect of various wound dressings.* Fruit growers have long 

 used paints, tars, waxes and other substances as coverings for 

 wounds of trees. The following paragraphs report the efi'ects of 



FIG. 118 POLE SAWS ARE ALL AWKWARD IN USE, MAKE RAGGED CUTS 



AND ARE UNDESIRABLE 



Nos. 1, 5 and 6 are freak devices. No. 2. Objectionable because double edged. 

 No. 3. Single edge straight blade. No. 4. Swivel type, the best pole saw if one 

 must be used. 



white lead, white zinc, yellow ocher, coal tar, shellac and avenarius 

 carbolineum on wounds made on apple and peach. The dressings of 

 these materials were applied when the pruning was done at various 

 seasons of the year and upon wounds of various ages. 



In all cases undressed pruning wounds healed more rapidly than 

 those whose surfaces were protected. Shellac seemed, the tirst sea- 

 son, to exert a stimulating influence upon the wounds, but the second 

 season this effect disappeared. Of all the materials used shellac 

 was least injurious. On the other hand it adheres to the wounded 



* G. H. Howe's summary and conclusions, somewhat condensed from New York 

 Agricultural Experiment Station Bulletin 396. 



