"WALNUT 



growth tlie first year, many of them not more than 6 

 inches. After this the srrowth is rapid. The trees are 

 tied to st;ikf< witl] strip- of cloth, since they are very 

 tender wlifii i,'r.iwiiiu'. and tlie swaying of the tree by 

 the wind ciuirkly raii-i - any other tie to cut through 

 the hark. Walnut tr.-.s are pnmed very little. At first 

 .•iiuall limbs are allowed to start about 

 the trunk, but later these are pruned off 

 to a height of i feet. Some of the longer 

 growths are shortened back while the 

 trees are young; and after they are older 

 the low limbs which bend down in the way 

 of cultivating are removed. 



The Santa Barbara Softshell begins to 

 bear the third year from planting, but 

 does not produce profitable crops before 

 the fifth or sixth year. Precocity in bear- 

 ing is nut a desirable quality in "Walnuts, 

 since no Walnut tree will produce a prof- 

 itable crop until it attains sufficient size 

 to support it. Hardshell trees do not 

 bear as young, and they are not regular 

 bearers. 



Walnut orchards in California receive 

 thorough tillage. They are heavily irri- 

 gated in winter, and plowed about 8 in. 

 deep in the spring. After this they are 

 irrigated and cultivated until the nuts be- 

 gin to fall, — about the 1st of September. 

 Late irrigation fills out the nuts and 

 causes the hull to open readily. Heavy 

 fogs are also desirable during harvesting. 

 The nuts are shaken down and picked up. 

 They are then spread in trays about 5 

 in. deep until dry, when they are bleached 

 and shipped to market. Walni 

 formerly bleached with fumes of sulfur, 

 but this was found injurious to the nut. 

 They are now usually dipped in a solution 

 of chloride of lime (chlorinated lime) and 

 sal-soda, to which a sufBcient amount of 

 sulfuric acid has been added to set free the chlorine. 



The majority of Walnut-growers are organized into 

 local associations. Representatives of these associa- 

 tions form the executive committee of the Southern 

 California Walnut-Growers' Association. This execu- 

 tive committee provides the form of contract which 

 the local associations may enter into with brokers, 

 and fixes the price. The local associations are man- 

 In some the growers bleach 

 their own crop, while in 

 others the association performs 

 this work at its own packing 

 house. 



The Walnut tree has very few 

 pests. The red spider some- 

 times attacks the trees, but it is 

 not considered a serious pest. 

 Of late years a bacterial growth 

 has developed to a considerable 

 extent which is more serious. 

 This attacks and destroys the 

 immature nut and the small 

 limbs of the tree. 



Akthur Staley. 



WALNUT 1961 



tricts in southern California, viz., Prfeparturiens, May- 

 ette, Chaberte, Parisienne, Franquette, etc. These va- 

 rieties are hardier in resistance of frost and leaf-burn 

 from summer heat. They are largely root-grafted upon 

 the seedlings of the California Black Walnut in the nur- 

 sery and are also being top-grafted upon old native trees. 



E. J. WiCKSON. 



The Walnl-t 

 California. Wain 

 is quite rapidiv .■ 

 both the coast and 

 ley regions of C'-n!r: 

 and is also success; 

 plished in favorahl 



IN Central 



ion of : 



2711. Juelans cinerea 



ituations 

 up to an eleva- 

 There are also 

 many instances of thrifty and 

 prolific trees in northern Cali- 

 fornia and southern Oregon. 

 This northward extension of 

 successful Walnut growing is 

 conditioned upon the use of the 

 best French varieties and the 

 rejection of the varieties popu- 

 lar to the chief commercial dis- 



2712. The California Wild Walnut - Juelans Calitorni 



Walnut Bacteriosis. — Chief among the more serious 

 diseases of Juglans regia in the United States is a bac- 

 terial blight of the nut, branch and leaf of that tree. 

 This blight now has its greatest development along the 

 Pacific coast, especially in Orange and Los Angeles 

 counties, California. The germ which causes this dis- 

 ease is a newly described species of Pseudomonas [P. 

 juglaiidis). Different effects of Ihe disease are shown 

 in Fig. 2714. 



The organism of Walnut bacteriosis winters in the 

 fallen nuts, in the diseased tissues of affected branches, 

 and especially in the pith cavity of the latter. New in- 

 fections occur as soon as spring growth begins, taking 

 place near the growing point of branches, in the open- 

 ing leaves, and upon the young and tender nuts. The 

 finer lateral veins of the leaves and the adjoining par- 

 enchyma are destroyed, and the midrib is often af- 

 fected. The injury re-nltinL' frt'ni inftcti'in nf tin- branch 

 will largely depeml ..n the trnd.-rn.>^ nf tin- latter at 

 the time and puint nf inl'.rti.m. If tin- <i-snr is tender 

 a canker-like s]".t will 1.. . ai. n tluapULrh tci the |)ith, or 

 the entire end of tin- -lni"i may be destroyed. If the nut 

 is infected while -mall, it- imnidete destruction usually 

 follows, the digfstivi- ai linn .if the germ involving hull, 

 shell and kernel. Xuts inf.cted early in the season 

 mnstlv fall when small, while later infections frequently 

 r. -nil unly in the destruction of the hull and the black- 

 . iiinLT nf the outer layers of the shell, the tissues bav- 

 in:; l.e.amu- too hard for the further progress of the dis- 

 ease. As in the case of pear blight, rapidly growing 

 trees are more subject to injury than those making a 

 slower and hardier growth. The spread of the micro- 

 organism through infected branches is generally only 

 local— it rarely extends more than a few inches from 

 the point of infection. A marked blackening of the in- 

 jured parts results from the rapid oxidation of the tan- 

 nic acid they contain, though this is not distinctive 

 of injury from this disease. Pseudomonas juglandis 

 is actively motile; hence fogs, rain or dew aid in its 

 spread and increase the number of infections. The 

 water of irrigation may carry the germ for miles. 



The destruction of the tissues of the Walnut is effected 



