WOUNDS ON TREES 515 



5. Coal-tar. — Coal-tar is sometimes useful as a dressing, especially 

 for shade or ornamental trees. Apply a thin coating to the wound. 



6. Tar for bleeding in vines. Add to tar about three or four times 

 its weight of powdered slate or some similar substance. 



7. Collodion for bleeding in vines. In some extreme cases two or 

 three coats will be needed, in which case allow the collodion to form a 

 film before applying another coat. Pharmaceutical collodion is better 

 than photographic. 



8. Cement for cavities. Rotten spots and cavities in trees should 

 be cleaned out to hard wood, the place filled solid with good cement. 

 (See Manual of Gardening, 145-151.) 



The grafting-waxes are applied to the cut surfaces of graft-unions 

 for the purpose of preventing evaporation of the plant juices, and 

 protecting from weather and the germs of decay. Buds covered by 

 wax will push through as they grow. The softer the wax when it 

 is applied, the closer will be its adhesion to the wood. Wax is often 

 applied to ordinary wounds ; but if the wounds are large they should 

 first be treated with antiseptics (as bordeaux mixture or similar 

 compounds). 



