PEAR GROWING IN CALIFORNIA. 



317 



left in the wood permanently, and which disinfect the wound as they 

 gradually go into solution. After treatment of the outside portions of 

 the cut with the asphaltum-paraffine mixture 1 and the insertion of the 

 nails into the wood, the entire surface of the cut is covered with 

 Bordeaux whitewash. 2 In addition to the use of copper nails a 

 copper screen was tacked over the wood of. the cut. This is recom- 



FIG. 124. The same cut shown in 

 Fig. 123, with the bark layer covered 

 with a thick coating of asphaltum. The 

 exposed surface of the cut has been 

 driven full of copper nails or tacks. 

 (After W. H. Volck.) 



FIG. 125. Same as F'ig. 

 124, with the additional 

 leature of a copper wire 

 screen as further protec- 

 tion against rot fungi. 

 (After W. H. Volck.) 



mended as a supplementary treatment and in the case of large cuts 

 becomes almost a necessity. 



While Mr. Volck 's experiments were conducted with apple trees, 

 the principles involved in pruning apples are the same as in the case 

 of all other trees, and his treatment which has been so satisfactory in 

 the apple orchards will, without doubt, be satisfactory with all other 

 fruit trees that are subject to wood rot from infections in pruning 

 wounds. The fact can not be over emphasized that no treatment of 

 the end of a stub, an inch or more in length, left by careless pruners, 

 can be of any value whatever, and the treatment outlined is to be 

 used only in cases of properly-made cuts. Many an orchard is ruined 

 beyond recovery by careless pruning. There can be no healing of 

 stubs without the return flow of sap from the leaves, and this sap 

 when on its downward course can not reach the ends of stubs that 

 have been left, consequently there will be no healing; drying out will 



'Asphaltum-paraffine grafting wax is composed of (D) grade asphaltum and 

 paraffine wax at the rate of 8 parts of asphaltum to 2 parts of paraffine by weight. 

 These ingredients are melted together until thoroughly mixed. 



2 Bordeaux whitewash used by Mr. Volck was made by thinning commercial Bor- 

 deaux paste with suitable quantities of water. 



