Report of Missouri Farmers' Week. 491 



air is excluded so there can be no fungus growth. If these decay- 

 producing organisms are deprived of one or more of the above 

 conditions, their growth is checked. In the case of fence posts it 

 is impossible to govern the temperature and air, so all attempts 

 toward prolonging the life of posts must be along the lines of 

 poisoning the food supply or reducing the moisture content. These 

 two things are accomplished by the proper use of certain preserva- 

 tives. 



There are several simple methods of lengthening the life of 

 posts which are worth mentioning. First and simplest, perhaps, 

 is seasoning. Wood, when cut, contains a considerable amount of 

 water. This is especially true of the sapwood. It also contains 

 more food material and so is more susceptible to the attacks of 

 fungi than is heartwood. No sapwood in its natural state is dur- 

 able — even the sapwood of the durable woods, like cedar and ca- 

 talpa, decay rapidly. By piling the posts so as to allow free access 

 of air all round them, the moisture content can be reduced to 15 

 per cent or 18 per cent, depending, of course, on the climate. It 

 it important to have all the bark removed so that the process of 

 seasoning may proceed more rapidly. 



Paints and other materials have been largely used in the 

 hope of preserving timbers. The practice is to be commended 

 provided the timbers are thoroughly seasoned. Otherwise, the 

 coating will make a moist chamber, a condition which favors the 

 growth of fungi rather than retards it. 



Another method is that of piling stones or gravel around the 

 base of the posts. This checks the growth of weeds and allows 

 a free circulation of air. It is doubtful whether the air circulates 

 freely enough to retard the growth of fungi by keeping the mois- 

 ture content below 15 per cent or thereabouts. 



Charring assists merely as an insulator, separating the wood 

 from the ground. Fungi cannot live in charcoal, there is no food 

 for them, and so the wood will not decay. Generally, however, 

 the process develops large cracks or checks in the wood so that 

 the interior is exposed. Fungi gain entrance through these checks 

 and the wood decays rapidly. 



Dipping of posts in a thin solution, of cement or similar ma- 

 terial has much the same effect as a coat of paint. Then, too, as 

 the wood will shrink or swell, cracks are made in the hard coat so 

 that fungi may enter. 



Oil paints are valuable for protecting wood against moisture. 

 Coal tar and pitch, especially if mixecj with turpentine and applied 



