166 



CALIFORNIA FRUITS: HOW TO GROW THEM 



by thoroughly soaking the land by winter irrigation and then by 

 careful summer cultivation he will be able to conserve enough water 

 in the soil to carry deciduous fruit trees or vines through bearing 

 and autumn bud formation without further water supply. But there 

 are other situations in which no amount of winter irrigation nor 

 rainfall will suffice for these ends. There are foothiH orchard areas 

 in which the winter rainfall is two or three times as "great as in the 

 valley situations where fruit is successfully grown without irriga- 

 tion, and yet water must be applied in summer on those foothills or 

 the fruit would be unmarketable and the trees in distress. The forty 

 or more inches of rainfall falling on a shallow soil underlaid by 

 sloping bedrock in some cases nearly sluices the cultivated soil from 

 its foothold, and yet the over-saturation in winter avails nothing for 

 summer growth, because most diligent cultivation can not retain 

 moisture enough in shallow soil thus situated to sustain bearing trees 

 in good crops of full-sized fruit. The same is true of valley soils 

 underlaid by hardpan. In such cases winter irrigation could add 

 nothing but distress to the soil over-soaked by rainfall, and summer 

 irrigation, well-timed and adequate, is the secret of success in the 

 orchard. The same conclusion, although for very different 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 in winter to carry trees through the 

 year. Thus we come again to the only safe generalization which can 

 be made, and that is, that everywhere water must be adequate to 

 the demands of the tree at the time it 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 ascertain, and to which 

 his policy and practice must conform. It is a fact, however, that, in 

 all situations of good rainfall, and for all soils, which are fairly deep 

 and retentive, winter irrigation, when water is most abundant, and 

 usually carries 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, therefore, 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 excessive irrigation as for excessive rainfall. The 

 grape and the pear are known to endure long submergence, but some 

 other fruits are susceptible to serious root-injury. 



