78 PREVENTIVE AND COMBATIVE MEASURES. 



wood during autumn, and partly to the consequent negative 

 pressure of air in the tree. .When pruning is undertaken in 

 spring or summer the tar altogether fails to enter the wood, 

 and the thin superficial layer does not prevent the cut surface 

 i'runi drying later and forming fissures into which water and 

 fungi may enter." From what has been said it follows that 

 dicotyledonous trees may be best pruned in the months of 

 October, November, and December perhaps also in January 

 and February, and that a good coat of coal-tar should be at 

 once applied to the wounds. 



Conifers should also be pruned in autumn and winter, for 

 although the wounds resulting from removal of small branches 

 with no heart-wood are soon protected by an excretion of resin, 

 yet thicker branches with heart-wood, which secretes no resin, 

 must be tarred over. Similar precautions are advisable to 

 protect the stools of trees felled in order to produce coppice. . 



Wounds are produced on fruit-trees by removal of branches, by 

 pruning and grafting, and again during the fruit-harvest. Hail 

 and wind are frequent sources of wounding. Gnawing of the 

 bark by animals, such as mice and other rodents, may also occur. 



Eed deer, by peeling off the bark, are a source of great 

 damage in the forest. In this way spruce plantations may be 

 so peeled, and in consequence so subject to red-rot that they 

 have to be prematurely felled. The trees which suffer most 

 are those like spruce, silver fir, Weymouth pine, and Douglas 

 fir, which remain for a considerable time smooth-barked, whereas 

 species with a rough bark are comparatively safe ; the latter 

 can also cover up any wounded surface by means of an excretion 

 of resin. Conifers suffer most from peeling, but the broad- 

 leaved trees are not quite exempt. At certain seasons the deer 

 rub the fur off the young antlers or knock off the old ; for 

 this purpose they generally choose younger plants, which, in 

 consequence of the injury, frequently dry up. Injury by deer 

 is more serious in summer than in winter, because with the 

 increased temperature and moisture the spores are able to 

 convey infection quickly and easily. 



Injuries similar to peeling by deer are produced in gathering 

 resin, and in the process of " testing " the timber of conifers. 

 Both practices are, however, prohibited in well-managed forestry, 

 and occur only as misdemeanours. Resin-collecting of whatever 



