ORANGE DISEASES 



1487 



ORANGE DISEASES 



Anthbacnose. See Wither Tip, this sec- 

 tion. 



Black Rot. See Navel Rot. 



Blue Mold 



Penicillium italicum and P. digitatum 

 The fruit shows a soft moldy decay, 

 the surface of the affected portion being 

 covered with a dusty mass of spores, of a 

 blue or green color, according as the 

 first or second named fungus is present. 

 The blue fungus is somewhat more ac- 

 tive than the green and causes occasional 

 infection by contact from one fruit to 

 another. 



The two fungi named above are the 

 commonest cause of decay in citrus fruit. 

 Only very slightly parasitic on uninjured 

 fruit; this decay is practically confined, 

 under ordinary conditions, to fruit which 

 has been injured in handling. 



The extensive demonstrations of the 

 United States Department of Agriculture 

 have established beyond question that cit- 

 rus fruit will keep indefinitely so far as 

 blue-mold decay is concerned, unless the 

 fruit has been bruised or injured in some 

 manner. Such injury comes about mainly 

 either through cuts in the stem end made 

 in clipping the fruit from the tree, from 

 rough handling during the process of 

 hauling to the packing house, or in grad- 

 ing or packing. As a result of the dem- 

 onstration mentioned above, the whole 

 practice of citrus-fruit handling has been 

 revolutionized along the line of more care- 

 ful handling, and implements and appara- 

 tus tending toward less injury in picking 

 and handling fruit have been developed. 

 Each year's experience goes more and 

 more to demonstrate the possibilities of 

 almost prevention of this commonest 

 form of decay through careful handling. 



Brown Rot of the Lemon 



Pythuacystus citrophthora R. E. Smith 

 Occurrence 



The brown rot of the lemon is a dis- 

 ease which has become very prominent 

 in the region of lemon production in 

 California during the past few years. It 

 affects more or less every operation hav- 

 ing to do with lemon production and mar- 



keting, and at the time of the investiga- 

 tions which were undertaken in Cali- 

 fornia for its control it seemed to threat- 

 en the stability of this industry. The 

 brown rot may be found in the orchard, 

 in the packing house, and in storage con- 

 ditions. 



Symptoms 

 The first indications of the trouble may 

 be noted in a brownish or purplish dis- 

 coloration of the rind, showing light on 

 the greener fruit and darker on the 

 yellow fruit. Both old and young, vigor- 

 ous and weak fruits alike are affected, 

 and the disease is particularly character- 

 ized by a marked and peculiar odor, by 

 its rapid spread from fruit to fruit, in 

 the packing house or while stored in 

 boxes, and by the presence of small flies 

 wherever the affected fruit is stored in 

 quantity. After storage for a week or ten 

 days there may develop upon the affected 

 fruit a white mold-like growth, and fre- 

 quently upon such affected Iruit there is 

 subsequently produced also the blue 

 mold Penicillium. The blue mold alone, 

 however, does not spread rapidly and has 

 not the peculiar odor of the brown-rot 

 disease. The disease may appear upon 

 fruit in storage, which seemed to be per- 

 fectly colored and sound when passed by 

 the washer. 



Control 

 The infection of the fruit usually takes 

 lilace in the orchards, and also subse- 

 quently by direct contact and also by the 

 operation of washing. It has been found, 

 for instance, that if uninfected lemons 

 are dipped in water in which diseased 

 ones have been washed, infection will in 

 time result on the healthy ones. In fact, 

 the ordinary wash water may itself con- 

 tain a large number of germs of this 

 fungus, and it may also live more or less 

 permanently in the machine used for 

 washing such fruit. The remedy, there- 

 fore, for such conditions is very simple 

 and merely consists in treating the water 

 used for washing purposes with some 

 aseptic or toxic agent. The most practical 

 method which has been devised consists 

 in using copper sulphate, formalin, or 

 potassium permanganate. In using for- 



