PREVENTING DISEASE 181 



important, and tarring or painting should 

 not be neglected, whether for the sake of 

 appearance or the health of the tree. The 

 extra weight of foliage often causes a branch 

 to become top-heavy and break across, this 

 being accentuated by the presence of an un- 

 usually large quantity of sap, which naturally 

 causes the timber to become brittle and more 

 readily susceptible to accident. 



The presence of fungus on a tree may be 

 taken as a sure indication that all is not right 

 with the timber, and, so far at least as the 

 public safety is concerned, the sooner such 

 a tree is examined and dealt with the better. 

 Insect attacks, particularly those of the goat 

 and wood leopard moths, are frequently the 

 cause of the sudden breaking of a limb or 

 branch, especially when the tree is in full 

 leafage or during stormy weather. The cater- 

 pillar of either insect tunnels into the wood 

 and causes it to become so weakened at the 

 point of attack that it readily breaks over 

 when subjected to the extra weight of leafage 

 or wind-pressure. 



Though hardly applicable, from a financial 



