BULLETIN 231] WALNUT CULTURE IN CALIFORNIA. 217 



to appear above ground, although if heavy rains occur before this time 

 the surface may crust over, especially on heavy soils, to such an extent 

 as to make it difficult for the young sprouts to break through the surface. 

 Under such conditions it may be well to go over the nursery with a rake 

 or light harrow in order to break up this crust. As the trees grow they 

 should be given good care, such as would be given to a crop of corn or 

 potatoes, by frequent cultivation and hoeing. Seedlings are grown 

 without irrigation in some localities, and there is a fairly common 

 impression that such trees are more hardy and desirable than those 

 grown under irrigation. We cannot coincide with this view, however, 

 having found no undesirable features in irrigated trees, while their 

 superior growth is desirable from every standpoint. As ordinarily 

 grown without irrigation, two seasons' growth is necessary to get the 

 majority of the seedlings up to sufficient size for grafting, while with 

 good soil and abundance of water, fine large trees of ample size for 

 grafting can be produced in one year, with roots proportionate to the 

 top in size and with no undesirable qualities whatever on account 

 of having been given sufficient moisture for their best development. 

 The difference, in fact, is fully as apt to be in the other direction, non- 

 irrigated trees being stunted and reaching grafting size only after 

 several years' growth. Again, in unusually dry years, non-irrigated 

 trees may be badly injured or even killed by drouth. 



GRAFTING. 



With good care and sufficient moisture the majority of the seedlings 

 should reach sufficient size for grafting during their first year's 

 growth and be ready for grafting during the next winter following 

 that when the nuts were planted. The size of tree which is suitable 

 for grafting depends largely upon the size of the scions available, 

 since seedlings can be used nearly down to the size of the smallest good 

 scions. In practice it will be found that trees of from one to two inches 

 in diameter close to the surface of the ground are best adapted for 

 grafting, while with the best of the smaller scions trees down to that of 

 three quarters of an inch or a little less may be used. This assumes 

 that the trees are grafted close to the ground. 



There are various methods of nursery walnut grafting in practice, 

 the majority of which we will not attempt to describe. The operation 

 at best is one which requires much skill and practice, the walnut being 

 less easily grafted than most fruit trees, and among those who are 

 doing the work successfully each has his own method to which he has 

 accustomed himself by long use and which might hold no particular 

 advantage for the beginner. We will, therefore, describe but one 

 method of nursery grafting, which is that which has proven most 

 successful with us. 



