8502 



WALNUT 



WALNUT 



The larger number of growers do very little systematic 

 pruning of the walnut except to remove the lower limbs 

 which interfere with cultivation. Occasionally, how- 

 ever, a grove is to be seen in which the branches are 

 annually thinned out. Such trees usually bear more 

 nuts on the main limbs near their centers than the 

 unpruned ones. 



Companion crops in bearing groves are seldom seen t 

 and in fact young groves, before they reach a bearing 

 age, are sometimes handled with clean cultivation. 

 The interplanting of young walnut groves with lima 

 beans or other hoed vegetable crops, small-fruits, 

 alfalfa, and occasionally apricots and peaches, is a 

 common practice. Certain intercrops, as beans, if 

 properly handled, will commence making returns 

 immediately without detriment to the future walnut 

 groye. Vegetable crops are preferable to tree crops 

 for interplanting. Peaches and especially apricots have 

 an apparent dwarfing effect on the young walnut trees. 

 Their use may be profitable, however, in the end in 

 spite of the injury caused. 



The older plantings of walnuts were set too close 

 together. Although 40 to 50 feet apart seemed ample 

 room for development, it is very evident now that a 

 distance of 60 feet is none too much for the larger-grow- 

 ing varieties on the rich loam soils which are best 

 adapted to this crop. It is a matter of common observa- 

 tion to see the outside trees in a grove produce con- 

 siderably more than the trees in the center. This leads 

 one to believe that perhaps some of the older planta- 

 tions might produce more walnuts today with fewer 

 trees to the acre. 



The older groves are composed entirely of seedlings, 

 most of which are of the Santa Barbara Soft Shell type 

 and trace directly or indirectly to the original trees 

 grown by Sexton at Santa Barbara. It is only within a 

 comparatively recent time, during the last ten to 

 fifteen years, that the walnut has been propagated by 

 budding and grafting in commercial quantities. During 

 this time, a comparatively large number of varieties 

 have been introduced and many of these have been 

 discarded even thus early in the development of the 

 industry. At the present time the following five varie- 

 ties are being propagated to a greater extent than all 

 other sorts combined: Placentia, Eureka, Franquette, 

 El Monte, and Prolific. In general, the first two men- 



tioned varieties compose nearly 70 per cent of the 

 trees propagated at the present time in southern Cali- 

 fornia nurseries. 



The several black walnuts are used as rootstocks. 

 The northern California species (J. Hindsii) is held in 

 the greatest favor at present. This is a strong vigorous 



3989. Juglans regia, the walnut of commerce. Often known as 

 "English walnut." 



3990. Black walnut. Juglans nigra. On the right is the bare nut; 

 on the left the husk not removed. ( X H) 



tree which will withstand adverse soil conditions much 

 better than the Persian walnut itself. Very few eastern 

 black walnuts (J. nigra) are used for propagation, as 

 they are usually thought to be less vigorous than Cali- 

 fornia species. The southern California black walnut 

 (J. californica) is little used at present, although it was 

 once popular (Fig. 3992). This species starts growth so 

 much earlier in the spring than the Persian walnut that 

 it suckers profusely when used as a rootstock. It is not 

 so rapid-growing as the J. Hindsii. Some of the nursery- 

 men are using the Royal hybrid as rootstock. The 

 Royal hybrid is the name commonly given to a cross 

 between J. nigra and either of the California species. 

 Some observers think the Royal hybrid root more 

 resistant to excessive soil-moisture and general adverse 

 soil conditions than any other rootstock. The Paradox 

 hybrid, which is a cross between J. regia and any of the 

 black species, is an exceedingly vigorous rapid-grow- 

 ing tree. This hybrid can be obtained by planting 

 black walnuts which were produced in the neighborhood 

 of J. regia trees. Such nuts will produce from 50 to 90 

 per cent hybrid progeny. Although this hybrid makes 

 an excellent root and produces an exceptionally large 

 and vigorous tree, it is rather impractical for general 

 use as it cannot be obtained in wholesale quantities. 



The nursery propagation of walnuts is usually by 

 crown-grafting in place. The black walnut root is 

 grown one year in the nursery and grafted the second 

 spring just before the leaves start to come out. A short 

 whip-graft is used, tied in place by soft cotton twine or 

 raffia. After tying, the graft and top of the cion are 

 covered thoroughly with hot wax. Some additional 

 protection is usually given to prevent the cion drying 

 out excessively. This is done by covering with a paper 

 bag or by hilling the soil over the union until growth 

 starts. The young trees are staked in the nursery, as 

 they are very supple, due to their rapid growth. The 

 one-year-old trees are preferred by most planters and 

 should be 6 to 10 feet high at this age. As the trees are 

 set in the orchard, they are usually cut back to about 

 5 feet. Some growers in the inland sections, however, 

 prefer to cut the trees back to 18 inches and then train 

 one sprout from the trunk of the tree. This sprout is 

 pinched back when it reaches a height of 5 feet. The 

 method necessitates staking the trees. At the end of 

 one season's growth such severely headed-back trees 

 may be as large as though they were left 5 feet high in 

 the beginning. The trees cut back to 18 inches grow 

 much more vigorously than trees only moderately 

 pruned. 



The harvesting of walnuts is done largely by Mexican 

 families who camp in the groves through the picking- 

 season. A portion of the nuts fall naturally to the 



