BULLETIN 231] WALNUT CULTURE IN CALIFORNIA. 203 



California black walnut is, therefore, not advisable if the grower desires 

 to produce the best possible trees upon this root. It is much better 

 to plant separately the nuts from various trees and determine the 

 nature of the offspring in each instance. Only trees of large produc- 

 tion should be chosen for this purpose, since it is not profitable to 

 gather nuts here and there from a great many different trees. Seed- 

 lings from the best types of the northern California species produce, 

 when worked to the English walnut, a thrifty, vigorous tree, of very 

 good growth, more resistant both to excessive moisture and drouth than 

 those upon the English root, not susceptible to gophers or root rot, and 

 in every way a very good, all-round tree. The root is only excelled by 

 certain special hybrids which will be discussed later. 



Southern California Black Walnut Root, Juglans californica. This 

 root has been quite commonly employed for the English walnut in the 

 southern part of California and has much to recommend it, particularly 

 for that part of the State where it has been most tested. The quite 

 common impression that the southern California walnut root has a 

 dwarfing effect on trees worked upon it is entirely erroneous, as such 

 is certainly not the case. The tree no doubt gets this reputation from 

 the fact that as it grows wild on dry hillsides it often has a dwarfed, 

 shrubby form. When planted in good soil, however, with even a mod- 

 erate supply of moisture, it is a tree of extremely rapid growth, 

 especially in diameter, and actual experience shows that with trees upon 

 this root there is no indication whatever of a dwarfing effect. In our 

 southern California nurseries we have found no walnut which gives as 

 uniform a growth of seedlings in the row or as uniformly good grafted 

 trees during the time that they are in the nursery as this. From 

 the nurseryman's standpoint, in the south at least, it is an ideal 

 tree, the nuts sprouting early and uniformly and the seedlings making 

 a uniform, vigorous growth kept up until very late in the fall. Trees 

 of this species remain green and still growing while the northern Cal- 

 ifornia and other forms have become dormant and dropped their 

 leaves in the fall, while in the spring they are the first to come out. 

 The tree is, therefore, especially good for budding on this account. 

 The southern California walnut unites readily with the English, and, 

 as we have said, for the southern part of the State at least, we believe 

 it to be one of the best roots. Other objections to this root have been 

 that it is especially susceptible to wet land and also that trees grafted 

 upon it are more apt to blow over than those upon other roots. The 

 first objection is not without foundation, since the southern California 

 walnut, from the first sprouting of the nut, is extremely susceptible 

 to an excess of moisture. This root should not be used for trees to be 

 planted on very heavy land which is likely to be extremely wet at times. 



