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THIRTY-FOURTH FRUIT-GROWERS^ COXVEXTIOX. 



in an even condition ; never have it call for anything ; never have it need 

 irrigation; never have it need fertilization; never have it need any- 

 thing, so far as indications are concerned. That is, you don't want a 

 grove to show you that it needs anything. You don't want it to arrive 

 at that condition where it will show this. ' ' We can give no better advice 

 than to emphasize what Mr. Chapman has said as to the importance of 

 maintaining a uniform, even condition and growth of the citrus tre(^ 

 avoiding all extremes and sudden changes which would tend to produce 

 irregular development. Whatever may be the exact nature and cause 

 of these obscure troubles, it is certain that they all have their origin 

 in irregularities of growth, or functions as influenced by natural con- 

 ditions, or the treatment which the tree receives. The peculiar sen- 

 sitiveness of citrus trees to the effects of such conditions makes it 

 particularly important that their vital processes be kept in a uniform 

 condition, free from violent shocks. So far as climatic influences are 

 concerned, this can not be entirely accomplished, but in his manner of 

 soil treatment as related to irrigation, cultivation, and fertilization, the 

 grower should study each peculiar type of soil most carefully, endeavor- 

 ing to maintain the most uniform possible condition as to water and 

 food supply. 



These troubles being of a physiological or autogenous nature, rather 

 than the effects of parasitic organisms, any application to the tree of 

 the nature of a fungicide or insecticide is ordinarily out of the question. 

 In the case of the Florida die-back, beneficial results have been claimed 

 from spraying with the Bordeaux mixture, in which case it is possible 

 that the application of this substance to the foliage has had some 

 physiological effect. 



Brown spot, Avhich has been so much in evidence during the past 

 season, is another trouble affecting the orange fruit. In regard to 

 this we can only say that it consists in a d^dng of the rind of the 

 orange in certain spots, drying out and turning broAvn. What causas 

 the rind to die in this manner can not at present be explained. Troubles 

 of a somewhat similar sort are found in the lemon, though fortunately 

 they are not of extensive occurrence. Of the fungous and parasite 

 troubles which affect our citrus fruits we have, as has already been 

 stated, very few, except those which cause the decay of the fruit. 

 Apparently the one fungous disease affecting the citrus tree at all in 

 California is a root rot, which occasionally occurs in citrus orchards, 

 though more commonly in those of deciduous fruits. This disease is 

 commonly found on land which has been cleared from a growth of 

 oak trees, a situation which is not common in the citrus districts. The 

 trouble consists in a rotting of the roots of the tree caused by toadstool 

 fungi, which propagate on the decaj'ing oak roots in the soil. We have 

 known of one instance of this trouble occurring on orange" trees. Of 

 fungi causing decay of the fruit, we have a considerable variety. 



The blue-mould fungus causes the ordinary form of citrus decay. 

 There are two different species of this mould quite common in Cali- 

 fornia, the more usual of which, the olive green form, is Penicillium 

 oilaceum, while the bright blue form, which is less common, is Peni- 

 cillium italicuni. 



The brown rot of the lemon, one of the most active forms of citrus 



