148 THE FARMERS HANDBOOK. 



POISONING GREEN TIMBER WITH SODIUM ARSENITE. 



A method that has been found useful for rapidly killing off the trees, 

 and at the same time reducing suckering to a minimum, is poisoning with 

 arsenite of soda, though it must not be supposed that this treatment 

 will cause such a change that within a week or so the trees will burn 

 readily. The usual drying-out must take place after the death of the tree 

 before it can be burnt. 



Arsenic — the ordinary white arsenious oxide of commerce — is not soluble 

 in water to any great extent, so that soda, either the ordinary washing soda 

 or caustic soda, has to be used to dissolve it. When large amounts of the 

 solution are required, washing soda will be the cheaper, but for small 

 quantities of solution, caustic soda will possibly be found the handiest. 



When preparing the solution, whether caustic soda or washing soda is 

 used, first dissolve the soda in a convenient amount of water, using heat, if 

 desirable, to assist and hasten it ; then slowly add the arsenic, which has been 

 previously made into a thin paste (as the housewife treats her cornflour), 

 stirring all the time ; place on a strong fire, and after it has come to the boil, 

 allow it to remain boiling for at least half an hour ; stir from time to time, and 

 be careful to stand on the side away from the fumes, as they are poisonous 

 and are apt to cause sickness. When the arsenic is thoroughly dissolved the 

 solution may be made up to the required bulk by adding the remainder of the 

 water, either hot or cold. 



A useful formula for quick and effective work in all kinds of timber is : — 

 Arsenic, 1 lb. ; washing soda, 1 lb., or caustic soda, i lb. ; water, 4 gallons ; 

 whiting, ^ lb. The addition of whiting is merely that it may serve as an 

 indicator On trees treated ; it turns white on slightly drying, clearly marking 

 the trees that have been operated on. An empty kerosene tin makes a useful 

 measure for dissolving in, as it holds 4 gallons. 



The best time to carry out the work of poisoning is when the tree is passing 

 into the dormant stage, that is, when the sap flow in the tree is ceasing. 

 This period varies in different districts, but as a rule it commences about 

 February. On parts of the North Coast ringbarking has been carried out to 

 best advantage as late as June, and early July in certain years. The main 

 object in catching the sap to season is to prevent suckering. Trees can be 

 killed by arsenic or ringbarking at practically any time of the year, but to 

 prevent this suckering it is necessary to operate when the sap is just com- 

 pleting its downward course. 



Having decided on the season and dissolved the poison, it is necessary to 

 " frill " the trees. By "frilling " is meant a succession of downward axe cuts 

 completely round the tree, each cut well overlapping the adjoining ones, so 

 as to leave no unsevered section of bark up which the sap can flow. There 

 is no doubt that "frilling" alone would kill timber if allowed time, but the 

 poison does it in a fraction of the time ; in fact, trees have been killed in a 

 few days. The cuts must be through the bark and well into the wood 

 proper, and as close down to the ground-level as is convenient to cut them 

 consistent with the shape of the tree, say, from 6 to 10 inches up. 



For trees of 4 feet in diameter, pour about a quart of solution into this 

 frilling, right round the tree, using an old teapot or kettle, as the spout makes 

 pouring easy, and less is wasted by spilling. Smaller trees naturally need 

 less solution. Saplings may be cut off lo*- clown, and the solution dabbed 

 on with a swab-stick to kill and prevent suckering. 



