WALNUT 



WALNUT 



3501 



English walnut because the supply yearly reached 

 America through England; also, by extension, to other 

 species of the genus Juglans. The name is sometimes, 

 but provincially, given to hickory-nuts. 



The walnuts may be thrown into three horticul- 

 tural groups: (1) The Persian or English domesticated 

 species, Juglans regia (Fig. 3989), the walnut of com- 

 merce and of extensive cultivation in California and 

 other parts of the United States. (2) The North 

 American walnuts, of several species but chiefly known 

 in the black walnut, J. nigra (Fig. 3990). (3) The 

 East Asian walnuts, represented by J. 

 Sieboldiana and allies, promising but yet 

 little grown in this country. To the genus 

 also belongs the butternut, J. cinerea 

 (Fig. 3991), sometimes called white wal- 

 nut. There is much promise of important 

 cultural races in the species of Juglans, 

 but the markets yet know practically 

 onlv the nuts of J. regia. See Juglans, 

 Vol. III. L . H. B. 



The walnut in California. 



The extent of the present Persian or 

 English walnut (J. regia) industry of 

 California amounts to between 45,000 and 

 50,000 acres, or about 1,250,000 trees. An 

 average crop for the past few years is 

 about 12,000 tons, valued at $3,500.000. 

 The crop for the year 1915 equaled 14.300 

 tons, valued at approximately $4,250,000 

 to the growers. The investment in the 

 \valnut industry of California represents 

 about $45,000,000. 



English walnuts may have first been 

 planted in California by the Mission 

 Fathers. However, it was not until after 

 the coming of the first Americans that 

 this industry attained any commercial 

 importance. The present walnut industry 

 is of comparatively recent origin and owes 

 its establishment to the early efforts of 

 Joseph Sexton, of Santa Barbara, and the 

 late Felix Gillet, of Nevada City. The 

 Santa Barbara Soft Shell seedlings and 

 the several grafted varieties of this type 

 all trace back more or less directly to the 

 efforts of Sexton. The French varieties, 

 such as the Mayette, Franquette, and the 

 like, owe their popularity to the tireless 

 work of the late Gillet in promoting the 

 production of this type of walnut. 



Commercial walnut-growing is largely 

 centralized in the following counties mentioned in 

 their order of importance: Orange, Los Angeles, 

 Yenturaj Santa Barbara, San Joaquin, and Contra 

 Costa. 



This industry is almost everywhere a specialized 

 crop. It is seld'om seen as one of two or more general 

 farm crops, but, on the contrary, nuts are the one and 

 only crop produced by many of the prchardists engaged 

 in this industry. Success with this crop depends on 

 the soil and climatic conditions and the availability 

 of irrigation water. A deep rich alluvial loam contain- 

 ing plenty of humus is desirable. Groves planted on 

 the light sandy loams or soils underlaid with a fluctua- 

 ting water-table or a hardpan within 4 or 5 feet of 

 surface are usually short-lived and unsatisfactory in 

 the end. Although good drainage is imperative to a 

 depth of at least 6 or 8 feet, irrigation water is neces- 

 sary throughout most of the walnut areas of California 

 for the best production of nuts. 



The walnut industry has been most successful through- 

 out the coast regions. In general, the high humidity 

 and frequent fogs, together with a relatively small 



daily range in temperature, seem favorable to this crop. 

 Walnuts grown inland are subject to sun-scald injury 

 on both the nuts and the trees. The inland regions are 

 subject to a very low humidity, an extreme maximum 

 temperature and a wide daily range. Some of the more 

 recently introduced varieties seem to endure the inland 

 conditions better than the Santa Barbara Soft Shell 

 seedlings. It seems very likely that the inland valleys 

 may yet be devoted to this crop with the proper choice 

 of varieties. 



Clean culture, with the use of a winter cover-crop, is 



3968. Wallichia disticha. 



the most prevalent type of soil-management practised 

 by the progressive growers. Such cover-crops as melilo- 

 tus clover, vetch, and rye are often seen. These crops 

 are usually planted immediately after harvest, the 

 latter part of September or October, and should be 

 nearly waist-high at the time they are plowed under, 

 in the latter part of March or April. 



Irrigation water is applied by the furrow system in 

 most cases, although occasionally a grove is watered 

 by the basin method, where the land is level or where 

 possibly a sod is grown in the grove throughout the 

 year. From one to five or six applications of water are 

 made in a season, depending on the moisture-holding 

 capacity of the soil and local climatic conditions. Each 

 irrigation should penetrate from 6 to 8 feet from the 

 surface of the ground in order to reach the entire root- 

 system. If the trees are irrigated a week or two before 

 harvest, the shucks will open and remain on the trees, 

 dropping the clean nuts to the ground. In case the 

 trees are drought-stricken at harvest, the shucks are 

 likely to become sunburned, stick to the nuts, and thus 

 cause an increase in harvesting expense. 



