BULLETIN 231] WALNUT CULTURE IN CALIFORNIA. 201 



way that roots can be definitely tested on different soils and in different 

 localities with any possibility of duplicating the same roots after their 

 qualities have been determined. 



In our own work the necessity of testing rootstocks as well as differ- 

 ent varieties of the nut itself was recognized from the first, and in 

 the planting of our experimental orchard on the Whittier State School 

 grounds, an effort was made to obtain trees of the various varieties on as 

 many different roots as possible when the first planting was made. 

 We soon found, however, that the roots of these first trees purchased 

 from various nurseries came a long way from representing definite 

 species or types, but that as a matter of fact they were a very much 

 mixed lot. After commencing propagation of our own, root-testing 

 was still kept in mind, and further plantings for this purpose have been 

 made. We have now trees growing on various types of soil in various 

 parts of the State and on different, definitely known roots, from which 

 plantings results of some value can be looked for. A few other 

 propagators are doing the same thing. Experience has abundantly 

 proven that on account of the extreme variation in the seedlings of 

 various black walnut trees and the freedom with which trees hybridize 

 or cross with any other walnuts in the vicinity, the matter of rootstock 

 must come down to a determination of the qualities of the seedlings of 

 certain individual trees rather than those of all the trees of any given 

 species or form. 



The general requirements in a root are that it should produce a 

 thrifty and vigorous tree, the more so the better, under as many differ- 

 ent conditions as possible. In other words, it should be one which is 

 not easily affected by unfavorable conditions, but which will produce 

 and maintain a good, thrifty tree even if the ground is a little too 

 dry or too wet, and upon as many different types of soil as possible. 

 Having a large variety of types to choose from, however, it is not to be 

 expected that any one root will be the best under all conditions bat 

 rather that we shall ultimately find one type to be the best for dry soil, 

 another the best where there is an excess of moisture, one for heavy 

 soils, one for light soil, and so on. At the same time a good all-round 

 root or one which is not easily affected by any variation from its 

 favorite condition is by far the best for general purposes. It is not 

 impossible that we shall ultimately find a difference in regard to varie- 

 ties of the English walnut as to root, some kinds doing better on one 

 root and others on another. There is already some evidence that this 

 is true. From the nurservman's standpoint, it is desirable that a tvpe 

 be chosen for the root wherein the parent tree is a large producer of 

 nuts, one in which the nuts srerminate readily and uniformly, producing 

 a uniform lot of seedlings with a ood affinity for the English walnut. 



