10 MISC. PUBLICATION 498, U. S. DEPT. OF AGRICULTURE 



TEARSTAINING 



Tearstaining or streaking may be due to several different causes 

 but is due chiefly to the melanose fungus (p. 5) and the citrus rust 

 mite (p. 22) and, rarely, Septoria and the anthracnose fungus (Col- 

 letotrichum) . Melanose tearstaining is caused by the melanose fungus 

 {Phomopsis citri) and occurs in the form of streaks where water from 

 rain or dew has run down over the side of the fruit, carrying spores 

 of the fungus with it and resulting eventually in infection and the 

 development of the typical pimples in the rind. It is much more 

 common than that caused by citrus rust mites. 



Citrus rust mite tearstaining occurs as brown streaks on the fruit, 

 the discoloration occurring solidly rather than as numerous small dis- 

 colored spots as in melanose tearstaining. The surface of the rind 

 in citrus rust mite tearstaining is fairly smooth, whereas in the mela- 

 nose form it is likely to be somewhat rough. 



In California a staining or streaking similar to that caused by the 

 citrus rust mite may be brought about by a light frost followed by 

 sunshine, the injury probably being caused by oil liberated from the 

 rind, causing streaks of discoloration on the rind as it runs down over 

 the side of the fruit. 



Tearstaining of lemons caused by the anthracnose fungus is known 

 to occur in California but is of relatively little importance. Anthrac- 

 nose tearstaining is rare in Florida and as observed there is indis- 

 tinguishable from the staining caused bv the citrus rust mite. 



WATERY BREAK-DOWN 



Citrus fruits affected with watery break-down are soft and spongy 

 and have a soaked appearance resembling that of fruit that has been 

 frozen. The flesh as well as the rind may be softened. In fruit in 

 this condition the carpels are loosely attached to the inner part of the 

 rind, and when a section of the rind is pressed, a watery substance 

 oozes freely from the albedo. 



Watery break-down is a low-temperature disease found most often 

 on fruit stored at temperatures below 40° F. However, even at 

 32° it does not develop until after several weeks of storage. Affected 

 fruits have a disagreeable odor of fermentation that is particularly 

 noticeable when they warm up after removal from storage. 



(See 23, 119, 125.) 



Lemons 



albedo browning 



Albedo browning is a discoloration of the white, spongy, inner part 

 of the rind. The disease may be evident externally only as a slight 

 darkening of the rind due to the discolored inner tissue showing 

 through the surface layer (pi. 7, A and B). It is believed to be in- 

 creased by low temperature storage (32° F.) and poor ventilation. 



ALTERNARIA ROT 



{Alternaria citri Ell. and Pierce) 



Alternaria rot has been found in all lemon-growing districts and 

 in some seasons is common on the market on both Italian and Califor- 



