162 CALIFORNIA FRUITS: HOW TO GROW THEM 



success in the orchard. The same conclusion, although for very differ- 

 ent reasons, must hold for soils underlaid by gravel or sand, and thus 

 too rapidly dried by leaching. 



But even this generalization must be accepted only for situations 

 endowed with conditions which justify it. There may be sloping hills 

 with shallow soil where winter rainfall does not amount to saturation, 

 Then winter irrigation to supply such irrigation is desirable, and then, 

 too, summer irrigation in proper amount and at proper intervals, will 

 also be demanded. Among the foothills, also, there may be localities 

 with depth of retentive soil in which water enough can be applied hi 

 winter to carry trees through the year. Thus we come again to the 

 only safe generalization which can be made, and that is, that every- 

 where water must be adequate to the demands of the tree at the time il 

 is needed, and whether it can best be applied in summer or winter, or 

 both, or whether it is not necessary to make any artificial application 

 at all, depends upon existing conditions which the grower must ascer- 

 tain, and to which his policy and practice must conform. It is a fact, 

 however, that all soils, which under good cultivation are fairly reten- 

 tive, winter irrigation, when water is most abundant, and usually car- 

 ries most sediment, can be made to go far toward making summer 

 irrigation unnecessary for all deciduous fruits. 



As to winter irrigation, practice varies, some relying upon a single 

 heavy flooding by using checks on contour lines, by which, perhaps, a 

 foot in depth or more of water is allowed to soak into the soil ; others 

 use the same method of application in winter as in summer, and, there- 

 fore, give a number of irrigations in winter. There is, of course, much 

 less danger of injury by water to deciduous growths in winter, because 

 they are dormant, though an eye should be kept on drainage for exces- 

 sive irrigation as for excessive rainfall. The grape and the pear are 

 known to endure long submergence, but some other fruits are sensitive 

 about it. 



Summer Irrigation. When this shall begin and when end are 

 to be locally determined. In some places even the earliest fruits can 

 not reach satisfactory size and quality without irrigation. In others 

 rainfall with winter irrigation will suffice for proper development of 

 early fruits, but not for late. In both cases the fruit may be satis- 

 factory, but the tree unable to hold its leaf vigor until the work of the 

 growing season is properly completed. It is then apparent that local 

 practice must vary in order to reach the universal fact, and that is that 

 all through the active season the tree must have constant and adequate 

 moisture supply. Many evils in lack of bearing, in dying back, in un- 

 seasonable activity and the like are due to inadequate, intermittent and, 

 in some cases, to excessive moisture in the soil. 



Cultivation and Irrigation. Although the relations of irrigation 

 and cultivation have been freely discussed, it must be remarked in this 

 connection that with such an extension of irrigation practice as is now 

 realized, there is danger that those who have previously trusted so 

 fully upon good cultivation may swing to the other extreme and trust 

 too much to the stream of water and too little to the plow and culti- 

 vator. There is a temptation this way when one finds that he can run 



