Levison : Filling Tree Cavities 



79 



could never reach or which would otherwise escape his eye. 

 When the cavity is absolutely freed from disease and insects its 

 interior is covered with a coat of white lead paint, which acts as 

 a disinfectant and also helps to hold the filling. The cavity is 

 then solidly filled with bricks, stone and cement, or with charcoal, 

 bricks and cement. The filling is allowed to set and harden and 

 after a day or two covered with coal tar to prevent the weather 

 from cracking the cement. The work can best be done in warm 

 weather. The cement is used mixed with two thirds fine sand, 

 and not only serves as a bed for the bricks and stone but also 

 forms the outer wall of the filling. The exposed face of the 

 filling must not be brought out to the same plane with the outer 

 bark of the tree, but should rather recede a quarter of an inch, 

 so that the living layer or cambium, which is situated immediately 

 below the outer bark, can grow over the cement and cover the 

 whole cavity, if it be a small one, or else grow out sufficiently to 

 overlap the filling and hold it as a frame holds a picture. The 

 growth of this living layer can be much accelerated by cutting 

 around the border of the orifice immediately before the season of 

 growth commences. The substitution of charcoal for a portion 

 of the bricks or stone is advisable in many instances because the 

 coal acts as an antidote against fungi and as an absorbent of 

 moisture. Where a cavity runs down a limb or trunk perpen- 

 dicularly, a mixture of pitch and sand can be poured down with 

 advantage in place of cement and bricks. 



The handling of cavities in this manner is not practiced very 

 extensively in this country, chiefly because the work is not usually 

 done properly and the resulting failures discourage the operators. 

 The cavity is generally not sufficiently cleaned and the disease is 

 allowed to continue its disastrous work behind the filling. The 

 cement is flushed out to the surface of the bark so that within a 

 year or two it either falls out altogether or else is pushed out by 

 the growing cambium forming crevices between the cement and 

 the wall of the cavity. The outer surface of the filling is seldom 

 tarred and is therefore directly exposed to the injurious effects 

 of the weather. The correct method of filling tree cavities has 

 been practiced extensively in Brooklyn for the past two years 

 with excellent results. 



Brooklyn Park Department. 



