1 8 SHADE TREE GUIDE. 



without attempting to fill it, cover the opening with cement, sheet- 

 metal, or wood blocks (creosoted), to guide the growing callus. 

 For small cavities a mixture of half cement and half sand is best; 

 for larger ones one part cement, one part sand and two parts 

 gravel, broken stone or cinder will answer. The surface of a fill- 

 ing may be smoothed with a coat of clear cement. The sand, stone 

 or cinder should always be free from dirt of any kind, the cement 

 thoroly mixed and as soft as it can be handled. 



Gas poison. If illuminating gas escapes from a faulty pipe into 

 the soil in which a tree grows the roots may be poisoned, cease to 

 function and the tree be weakened or killed. The extent of the 

 damage, and the rapidity of action, depend upon the quantity of gas, 

 the porosity and moisture of the soil, and the chaVacter of the pave- 

 ment or other ground cover. A little gas may find its way to the 

 air and do no great harm; a large quantity can kill in a day every 

 tree whose root system it penetrates. If a tree is killed while it is 

 leafless, it may give no sign until the following spring when its foli- 

 age fails to come out, or, coming out, is weak and soon falls. The 

 only sure test for gas is the odor. If a leak is suspected make a 

 hole with a crowbar or auger about two feet from the tree and two 

 or three feet deep and apply one's nostrils to the opening. If gas 

 is indicated the leak must be found and stopped at once. Some- 

 times a tree subjected to gas can be saved by trenching about it and 

 watering the soil freely, but most cases are hopeless unless only a 

 little gas has escaped. 



Fire must not touch a valued tree. Even the slight heat given off 

 by a burning leaf pile may cause serious injury. 



Salt, lime. Many trees are killed by having brine from ice- 

 cream tubs, or from salt used to melt pavement ice, penetrate to 

 their roots, and some are lost by an excess of lime water washed 

 from nearby mortar beds. Preventive measures only are effective. 



Electricity. Ordinary electric currents never injure the vitality 

 of a tree, and wires carrying a high potential current which might 

 do damage, especially in wet weather, are bound to be properly in- 

 sulated to save loss of power. The injury that trees suffer from 

 electric wires is invariably a cutting or local burning caused by 

 friction between a loose wire and a branch, or, more often, the 

 mutilations performed by careless or ignorant linemen. The rules 

 of the electric companies forbid their employees to use any tree 

 without the consent of the owner and provide for expert super- 

 vision of any tree trimming that is authorized. Linemen fre- 

 quently ignore these rules, but no tree need suffer if its owner will 

 take the trouble to report the case to headquarters before the dam- 

 age is done. In many cases the company will completely trim and 

 fix up a tree for the privilege of carrying their wires thru it. In 

 this State an owner should always be represented by a Shade Tree 

 Commission. 



