BULLETIN 231] WALNUT CULTURE IN CALIFORNIA. 371 



has been necessary. Various other growers have top-worked a greater 

 or less number of orchard trees with varying success. The whole 

 matter rests largely upon the skill of the operator who does the grafting 

 and the care and attention given to the trees after grafting until the 

 new tops are well established. Men who are able to top-graft the 

 walnut with fairly uniform success are decidedly uncommon and yet 

 there is no particular mystery or secret about the operation. It depends 

 entirely upon mechanical skill in this sort of work, knowledge and 

 judgment of the peculiarities of the walnut tree, and particularly upon 

 great care, thoroughness and attention to details in selecting and keep- 

 ing the scions, doing the grafting, and the subsequent care of the grafts, 

 especially during the first season. Unless prepared to give the work 

 this special care and attention until new tops are well established upon 

 the trees we would not advise any grower to attempt to improve his 

 walnut grove by top-working. If, however, he can give the work such 

 attention, either in person or through reliable, competent help, we would 

 strongly advise any grower to follow Mr. Neff's example, pick out his 

 poorest trees and work them over into a better variety, either by select- 

 ing scions from an especially good tree in the immediate neighborhood 

 or by putting in some good variety among those which we describe 

 elsewhere. Again, however, we would emphasize the fact that if the 

 grower cannot undertake this work with the assurance of giving it 

 careful, continuous attention, he would much better leave his grove in 

 its present condition z since otherwise he will find himself with a lot of 

 trees composed of a mass of sprouts coming from the cut-off branches, 

 the latter decaying and dying back in the stubs where they were cut, 

 leaving the grove in much worse condition than before. 



Other than top-grafting, the only method of bringing about improve- 

 ment in a seedling grove is by means of more regular and abundant 

 irrigation, pruning and thinning out the tops if they are too thick, 

 heavy fertilization with stable manure or nitrogenous fertilizers, and 

 such other improvements in cultural practice as may suggest them- 

 selves. These matters we have discussed on pages 182-192. 



The problem of the seedling walnut grove is being readily solved in 

 many portions of southern California by the rapidly increasing value 

 of land and the prosperous condition of the citrus industry. Many 

 hundreds of acres of thrifty seedling walnut trees have been cut out in 

 Los Angeles and Orange, and, to some extent, in Ventura County, during 

 the past few years, and planted to citrus fruits, especially lemons. At 

 the high valuation now placed upon the best land in these counties, it is 

 doubtful if any present variety of walnut could compete with the lemon 

 or Valencia orange, and the walnut acreage is very rapidly being trans- 

 formed into citrus groves. This tendency becomes more and more pro- 

 nounced every year. 



