MARKET DISEASES OF FRUITS AND VEGETABLES 19 



which the rind around the stem button or elsewhere on the upper part 

 of the fruit becomes wilted and shriveled, with or without collapse of 

 outer rind tissues (pi. 12, A). This condition is apparently caused by 

 loss of water from the fruit and is frequently accompanied by a brown- 

 ing of the affected areas and collapse of the oil glands (pi. 12, B). 

 Browning, however, may also be caused by improper conditions in the 

 coloring room or by the use of heated solutions in washing the fruit or 

 in the "color-added" process (pi. 12, G). In examining oranges or 

 grapefruit from storage it is sometimes difficult to tell with certainty 

 whether the small brown sunken spots found are pits or "aged" spots. 

 For the present it seems desirable to call such spots aging if they occur 

 near the stem and are dark brown, and pitting if they occur on the 

 lower part of the fruit and are dark to light brown or not discolored 

 at all. 



Fruits showing extreme symptoms of aging, accompanied by brown- 

 ing, usually have an off or aged flavor. 



Another form of aging -found late in the season of any variety of 

 tangerines and oranges is the development of minute cracks, in roughly 

 concentric pattern, in the rind around the stem. These cracks may 

 develop on normal-colored rind, but later the affected area turns a pale 

 brown or tan, and still later a few large pits may develop on the af- 

 fected area. This condition may be found even before the fruit is 

 harvested. 



ANTHRACNOSE 



(See Grapefruit, Anthracnose, p. 3, and pi. 1, A.) 



BLACK ROT (ALTERNARIA ROT) 



(Alternaria citri Ell. and Pierce) 



Black rot is particularly serious in California navel oranges and 

 occurs as a brownish or black slow decay at the stem end or the stylar 

 end of the fruit (pi. 13, A-D ) . Infection takes place through the navel 

 when the fruit is young and is apparently responsible for part of the 

 June drop. Affected fruits that do not drop but remain on the tree 

 usually color ahead of the main crop. They may show the disease only 

 when cut, or they may, in transit or storage, develop a rot that involves 

 the whole blossom end and is visible from the outside. When only the 

 interior of the navel is affected the tissues are black; wmen the decay 

 reaches the outside the rind shows merely a dark-brown color. The 

 disease is sometimes found accidentally in a lot of oranges that is being 

 cut for transit freezing injury, when otherwise its presence would not 

 have been suspected. 



Black rot sometimes causes rather heavy loss in the grove but is not 

 common on the market. It develops rather slowly at temperatures 

 below 50° F. but is sometimes found even at 32° on both grapefruit 

 and oranges held for 8 to 10 weeks (pi. 13, C). 



(See 33,43.) 



BLUE MOLD AND GREEN MOLD ROTS 



(Penicillium italicum Wehmer and P. digitatum Sacc.) 



OCCURRENCE, SYMPTOMS, AND EFFECTS 



Blue mold and green mold rots, sometimes known as penicillium rots, 

 are probably the commonest of all the rots that affect citrus fruits. 



