200 FARM FORESTRY 



has been poisoned, so that the fungus is deprived of its food 

 supply, will never decay as long as the poison remains in the 

 wood. The methods of preserving wood are based on this 

 principle of depriving the fungus plant of its food by poison- 

 ing the wood. This is the only factor that can be controlled 

 practically in fence posts. 



How the Life of Fence Posts can be Lengthened. — The 

 drier a post is kept the longer will be its life. Draining the 

 surface water away from a post will help to prolong its life. 

 Piling stones, ashes or gravel around a post will help to drain 

 away moisture and will keep down the weeds and grass that 

 spring up about a post keeping the base moist and so subject to 

 decay. Sometimes posts are set in cement or concrete. Because 

 of the shrinking and swelling of wood with moisture this is not 

 an effective method. The cement is cracked by the swelling of 

 the posts and in dry times the posts will shrink and will not 

 completely fill the cavity in the cement allowing the spores of 

 fungi to be washed down between the wood and the cement. 

 Coating a post with cement has the same objection. 



Jt is possible to prolong the life of fence posts by pre- 

 venting the entrance of fungi. Charring the ends of posts will 

 cover them with a layer of charcoal through which the fungus 

 can force its way only with difficulty. It also hardens the 

 wood and may produce changes in the composition. In char- 

 ring wood the danger lies in the wood checking badly and 

 splitting open. The posts must be well seasoned. The charred 

 portion must extend 8 to lo inches above the surface of the 

 ground when the posts are set. Wood that is kept well painted 

 does not easily decay, because the layer of paint keeps out 

 the fungus. If wood is wet when painted, however, it makes 

 the wood especially liable to dry rot should that fungus gain 

 entrance. Tar, pitch and various kinds of oils and other sub- 

 stances can be used for coating fence posts with considerable 

 success. Surface coatings are of but temporary value. They 

 are easily worn or broken off subjecting the wood to decay. 



