202 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



The nurseryman growing any considerable number of trees cannot 

 afford to run about picking up a few nuts from a tree here and a tree 

 there, even though they may give seedlings of unusual excellence. Hav- 

 ing found good trees from which to propagate, some nurserymen are 

 coming to the practice of reproducing a considerable number of these 

 trees by grafting and planting them out on their own grounds for seed 

 production purposes. 



English Walnut Root. The propagation of the English walnut 

 upon its own root has been almost entirely abandoned in California. 

 This is on account of the fact that this root, while very vigorous and 

 thrifty under perfectly favorable conditions, is easily affected by ad- 

 versity and very susceptible to unfavorable conditions, either perma- 

 nent or temporary, such as dryness, excessive moisture of the soil or 

 any other condition not perfectly favorable. The English root delights 

 in a deep, fertile, well drained, fairly heavy soil, with uniform and 

 abundant moisture, and under such conditions trees grafted upon it 

 are thrifty and vigorous, but experience has shown that comparatively 

 slight variations, such as dry years or other influences, react very 

 quickly and unfavorably upon trees on this root. The root is also 

 more susceptible to crown gall, gophers, root rot and some other 

 injurious influences than are those of any of the black walnuts. For 

 these reasons propagation upon the English root is practically obsolete 

 in California. 



Eastern Black Root, Juglans nigra. This root has been tried to 

 some extent in California, but the species is of such extremely slow 

 growth in this State as compared with other black walnuts that it can 

 scarcely be considered as a commercial root for general use. The im- 

 pression is general that this root is better adapted to wet land than 

 any other, on account of the native habitat of the tree in river valleys. 

 Even under such conditions, however, it is probable that for use in 

 California a better root can be chosen for planting in any soil which 

 is worthy of consideration for walnut culture. 



Northern California Black Root, Juglans hindsii. The black walnut 

 of northern California is an extremely thrifty, vigorous tree under 

 most conditions at all favorable to tree growth, and this is one of 

 the most popular and satisfactory roots for the propagation of the 

 English walnut. For general use, where no special study of selection 

 of rootstocks is made, it is probably the best root which can be recom- 

 mended for California planting. It should be remembered, however, 

 that the progeny of various individual trees of this species vary greatly, 

 and the seedlings of some trees are much more uniform and much 

 better trees than those of others. Indiscriminate planting of northern 



