222 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



weight of accumulated snow, &c., breaks off the dead 

 branch, leaving the projecting basal portion : if the 

 branch broke off quite close to the stem, the wound 

 would, or at least might, soon be occluded ; but, as it 

 is, the projecting piece not only takes longer to close 

 in, but it tends to rot very badly (Fig. 33), and at the 

 best forms a bad " knot " or hole in the timber when 

 sawn up. Of course what has already been stated ol 

 cut branches applies here : the wounds are 

 sources of danger so long as they are exposed. 



It is beyond the scope of this chapter to set fort 

 the pros and cons as to the advisability of adopting 

 any proposed treatment on a large scale : the simple 

 question of cost will always have to be decided b} 

 those concerned. But whether it is practicable or not 

 on a large scale, there is no question as to the desira- 

 bility of adopting such treatment as the following to 

 preserve valuable trees and timber from the ravages 

 of these wound-parasites. Branches which break off 

 should be cut close down to the stem, if possible in 

 winter, and the clean cut made so that no tearing or 

 crushing of the cambium and cortex occur ; the sur- 

 face should then be painted with a thorough coating 

 of tar, and the wound left to be occluded. If 

 the cutting is accomplished in spring or summer, 

 trouble will be caused by the tar not sticking to the 



