GRAFTING THE WALNUT 437 



in the center of the scion. Care should be taken to cover all exposed 

 surfaces. 



Grafting over is desirable either for substituting a better variety of 

 English walnut, or for working over a California black walnut into an 

 English variety, and as much attention is now being paid to blight 

 resistant, interest is sharpened in grafting methods. Mr. J. B. Neff, 

 of Anaheim, who has looked into the subject deeply and worked 

 over many old trees, gives the following practical suggestions on this 

 work: 



If the trees are from three to five inches in diameter they may be cut off at 

 about four feet above the ground and below the branches, then four or five scions 

 may be placed in one stock, or three or four of the branches may be cut back to 

 within 10 to 24 inches of the trunk and two or three scions placed in each. All 

 the other branches should be removed from the trunk. 



Old trees of from 12 to 20 years should have the branches cut at places where 

 they are from three to six inches in diameter, and from five to eight stubs left, 

 which will be from three to six feet in length and should have as many as six 

 scions in the large stubs, the other branches being removed before the scions are 

 put in place. 



In sawing large branches it is necessary to make two cuts, the first being 

 some distance above or outside the final cut, to prevent splitting the stub, or the 

 trunk, when the severed part falls. 



The scion should always be of solid, mature wood, that is, with as small pith 

 as can be had readily, and must have good living buds. Each scion should be 

 about one-quarter inch in diameter and have at least two buds. The growth 

 having buds close together is best, as shorter scions can be used. 



To receive the scions use a heavy butcher knife and mallet to split the stubs, 

 placing the knife across the stub as if a chip one-half to five-eighths-inch thick 

 was to be taken off. Then depress the handle of the knife to an angle of 30 to 

 45 degrees and split the edge down to 2y 2 to 3 inches, allowing the knife to 

 reach the farther side of the stub, but not making the split entirely across the 

 stub. Open the cleft with an iron wedge J4 to 5^-inch wide and thickest on one 

 edge, placing the thickest edge toward the outside. 



Trim the cleft in the stub with a sharp knife so it will be smooth. Then 

 cut the scion so as to fit perfectly and place it so the inner bark (the cambium 

 layer) of both will be on the same line, or at least will cross twice, then remove 

 the wedge and put hot wax over all the cuts on both stock and scion at once. 



The scions should be examined frequently and any excessive flow of sap 

 wiped off, and the stub re-covered with wax as soon as dry. Excessive flow of 

 sap for several weeks will cause the loss of the scions, as the callus can not form 

 in water. This may be controlled by boring one-fourth inch holes in the body of 

 the tree near the ground. Three or four holes four inches deep will be sufficient 

 to control the flow of the largest trees. No damage is done to the body of the 

 tree, as the holes soon grow over. 



The last two wax formulas on page 78 are largely used in walnut 

 grafting. For grafting in the stems of seedlings or in the smaller 

 branches of young trees a side graft as described on page 80 is success- 

 fully used as are also several styles of cleft grafting. One which is 

 used by Mr. R. Wiltz and others at San Jose consist in splitting a short 

 stub of a small branch which has been cut about four inches from its 

 attachment to a larger branch of stem. In this case the split can only 

 extend to the closely knit wood in the crotch and the scion is pushed 

 down strongly to the bottom of such a split and it is held tightly. The 

 two pieces of the deep split are not cut away but are allowed to protect 

 the short scion which is between them and if buds start on these pieces 

 they are allowed to grow a little to keep the stock from dying back. 

 When the scion starts well they are removed. 



