PROPAGATION OF PLUMS 273 



At some points subject to direct coast influences, there is sometimes 

 loss by cracking of the fruit. It is seldom encountered in the in- 

 terior valley, except near the rivers or in draws where the damp 

 coast air makes its way through. It seems to be worst where there 

 are marked differences in atmospheric humidity within short periods 

 of time. Where the percentage is quite uniformly high or low there 

 seems to be less trouble. Some years conditions usually restricted 

 to more exposed coast situations prevail in the interior valley, and 

 the result is unusual prevalence of mildew and other moist fungi 

 and cracking of fruit also, though they have no relation to each 

 other except that the same conditions favor both. Only certain 

 varieties are thus affected, and they can be avoided where the 

 trouble is found to exist. 



It was for a long time held that Southern California was not 

 adapted to the growth of the plum, but the experience of the last 

 few years has shown that the conclusion was too broad. The 

 "French pruns' demonstrated its success adjacent to the Coast in 

 Santa Barbara County, and elsewhere, in the low, rich lands of the 

 Santa Ana Valley, of Orange County, in the interior at various 

 points on the rim of the San Gabriel Valley, in Los Angeles County, 

 notably at Pomona, and still farther inland in the San Bernardino 

 Valley, but the Southern California prune product is small because 

 the land and water can be more profitably used for other fruits. 

 There is, however, difficulty in some dry uplands where the tree 

 is shy in fruiting and subject to serious gumming; but this is en- 

 countered locally in all parts of the State. Irrigation does not 

 always overcome these troubles, and yet, no doubt, the arrangement 

 of proper moisture conditions is important. The tree should be 

 helped to make one good growth and to ripen its wood in the fall. 

 To have growth checked by drouth and a second start made later 

 in the season is not desirable. 



All the foregoing observations are based upon the behavior of 

 plums of European origin ; descendants of the Prunus domestica. 

 One of the grandest contributions to the extension of the range of 

 the plum in California was the introduction of the Asiatic species, 

 Prunus triflora and simoni. Varieties of these species directly intro- 

 duced or locally developed by Burbank and others, have proved 

 productive in places where the domestica varieties were abandoned 

 as shy or sterile. To estimate the value of these varieties one has 

 only to visit the home fruit gardens of Southern California or in- 

 spect the fruit stands of Los Angeles which are continuous exhibits 

 of fine specimens of these varieties in their seasons. Even in places 

 where the domestica varieties are largely grown the Asiatic varieties 

 are also prominent. 



SOILS AND STOCKS FOR THE PLUM 



With the plum, as with the apricot, the subjects of soils and 

 stocks are intimately related, but the whole matter has been wonder- 

 fully simplified by the experience of the last few years. This relief 

 has come through the adoption of the myrobalan, or cherry plum 



