370 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



that it will eventually result in the entire replacement of the seedling 

 tree by definite varieties propagated by grafting or budding. In our 

 most familiar instance, that of the orange, the problem of what to do 

 with the thrifty old seedling grove has been easily solved by top-working 

 these trees to better varieties. With the orange and other citrus fruits 

 this is a comparatively easy operation. With the walnut, however, it is 

 by no means as simple and yet not at all impossible. A few growers, 

 notably one, have attacked the problem in this way with very excellent 

 results. Mr. J. B. Neff, of Anaheim, who had an old walnut grove 

 planted as seedling trees, commenced a systematic effort several years 

 ago of improving his trees by top-working. For several years he 

 observed the grove carefully, picking out the poorest-producing and 

 most blight-susceptible trees, and also one tree which seemed by far the 

 heaviest producer and least affected by blight of any in the orchard. 

 Having located his very poorest trees and the best one, he commenced 

 operations by cutting off the tops of the poor trees just above the main 

 forks and top-grafting them with scions from the good tree. The suc- 

 cess of the first year's grafting was very good, although some misses 

 occurred which had to be worked over again the next year. During the 

 second year more trees were cut off and worked, and with the working 

 over of the previous .year's misses the whole work extended over three 

 or four years before the grove reached a condition satisfactory to the 

 owner. The ultimate outcome has been, however, that the average 

 quality and productiveness of trees were very much increased, and 

 after about four or five years practically all the grafted trees have as 

 large tops as those which had not been top-worked. As to the effect of 

 this work upon the production of the grove, Mr. Neff states that he does 

 not think that the cutting off of the poorest trees diminished his total 

 crop after the first year. One eighth of all the trees in the orchard 

 were top-grafted the first year and one fourth of the total trees the 

 second year, making altogether three eighths of the trees which were 

 cut off and worked over. The total number of trees cut off and grafted 

 was about 200. In 1907, the year previous to the first grafting, the 

 total crop was 20,406 pounds. The grafting was done in 1908 and 1909. 

 In 1911 the total crop was 26,297 pounds. During the intervening 

 years the crop was smaller than in either 1907 or 1911, varying consid- 

 erably along with the walnut production at large in southern California. 

 Mr. C. B. Franklin of Carpinteria has also done considerable work 

 along this line, working over his poorest trees into better kinds. At 

 the Pasadena City Farm, near Alhambra, a large number of seedling 

 trees about six years of age have been worked over into various varie- 

 ties, in this case top-grafting a whole row or a solid block of trees at one 

 time rather than picking out the poorest ones. The work here was 

 quite uniformly successful at the first attempt and very little regrafting 



