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(3) Keep the wound thoroughly painted or covered at all times 

 until it is completely sealed over by a new growth of callus. 



(4) If the top-working was originally done in such a manner that 

 the removal of all the decay results in a cavity that cannot be prop- 

 erly drained, it is advisable to fill the cavity with some waterproofing 

 and antiseptic material in order to prevent it holding water and also 

 to assist the cambium in covering the wound. The cavity must first 

 be treated in accordance with approved tree surgery practices. In 

 shade tree work, quite a variety of substances have been used to fill 

 cavities witli more or less success; e. g., wood blocks and strips, 

 asphalt and sawdust, asphalt and sand, clear coal tar, clear asphalt, 

 elastic cement, magnesian cement. Roman (or Portland) cement, etc. 

 Of these only two — wooden blocks and Portland cement, have been in 

 general use more than a few years. Blocks of wood were used in 

 France to fill cavities more than 60 years ago. and in this country 

 to some extent about 50 years ago. Later, Portland cement was used 

 in preference to wood for fillings, probably mainly because it was more 

 easily handled. To us of the present generation, Portland cement in 

 combination with sand is the one material that seems to have been in 

 general use sufficiently long to allow us to draw any seemingly reliable 

 conclusion as to its real merits. 



For the personal use of tlie average orchardist. Portland cement 

 is one of the last in the list mentioned above that I would recommend. 

 According to a few reports that have reached me. wooden blocks and 

 tar proved to be fairly satisfactory half a century ago, and strips of 

 wood embedded in some flexible and antiseptic material, are proving 

 very satisfactorj- today. An excellent preparation to use between the 

 strips of wood, containing asphalt and asbestos, can be readily bought 

 on the market, and it has the advantage of being mixed ready for use. 

 For cavities with horizontal openings that will hold semi-fluid sub- 

 stances, clear asphalt or gas-house (coal) tar may answer all purposes. 

 For cavities with oblique or vertical openings, or for those on the un- 

 derside of a limb, probably some of the magnesian cea:ents. which 

 readily adhere to wood, will be found more satisfactory when prop- 

 erly mixed and applied. 



Although I have said more about filling cavities than of other 

 phases of the work, I do not wish the impression to go forth that I 

 recommend such work except as a last resort, so to speak. The one 

 thing that I do most emphatically recommend above all others is the 

 prevention of decay so far as possible by practices that are less 

 likely to allow decay-producing organisms to gain entrance in the 

 first place, or at any other time. 



