PRESERVATIVES AND MATERIALS 207 



too rigid, a mixture of sawdust and asphalt 

 makes an excellent filling for hollow trees, 

 particularly such as are growng in exposed 

 situations and are apt to get swayed about by 

 the wind. The materials are dry sawdust and 

 solid asphalt, one part of the latter to four of 

 the sawdust of oak or beech. 



Fungicides. Some of the larger-growing 

 fungi that attack forest and other trees can 

 most successfully be dealt with by carefully 

 removing the growth and, after cleaning and 

 dressing the wound, treating the affected stem 

 or root with a suitable antiseptic. In the case 

 of minute fungi, however, scraping or scrub- 

 bing the bark and wood and painting or spray- 

 ing with a recognised fungicide will be 

 sufficient. 



Where the fungus has permeated the diseased 

 wood of a tree, it is almost impossible to deal 

 with the attack ; but when it only occurs 

 between the bark and wood, remedial measures 

 may often be adopted. For the destruction 

 of fungus spores nothing equals sulphide of 

 potassium, also known as liver of sulphur, 

 or copper sulphate. Sulphide of potassium in 



