MARKET DISEASES OF FRUITS AXD VEGETABLES 13 



fungus is able to grow to some extent even at temperatures close to 

 freezing and hence may cause damage in transit at the temperatures 

 ordinarily provided for lemon shipments. Careful handling, packing- 

 house sanitation, and washing the fruit in hot water, as for brown 

 rot (p. 12), are recommended preventives. 

 (See 42, 43, 95,104.) 



FREEZING INJURY 



(See Oranges. Freezing Injury, p. 27. and pi. 16. A-C.) 



FUMIGATION INJURY 



(See Oranges. Fumigation Injury, p. 28, and pi. 14. C and D.) 



GRAY MOLD ROT 



(Botrutis cinerea Pers.) 



Gray mold rot, caused by the fungus Botrytis cinerea, has been re- 

 ported from most of the important citrus regions of the world, but it 

 is more common on lemons than on other citrus fruits. 



The early stage of the decay may closely resemble cottony rot, but 

 distinguishing characteristics are soon evident. The color of the de- 

 cayed area is darker, passing from cinnamon brown to various shades 

 of dark brown, and the mycelium that develops in moist air is gray 

 instead of cottony white (pi. 10. A). A characteristic feature of the 

 mycelium is the gray, granular-appearing spore tufts. 



The rot may be found in the orchard but is most common in transit, 

 in storage, or on the market. Control measures are similar to those 

 for brown rot (p. 12). 



(See #,£?.) 



INTERNAL DECLINE ( ENDOXEROSIS ) 



OCCURRENCE, SYMPTOMS, AND EFFECTS 



Internal decline is known at present only in California lemons. It 

 is more prevalent in the drier interior valleys than in the more humid 

 districts near the coast. All the varieties grown in California are 

 susceptible. 



Internal decline is a breaking down or drying out of the tissues 

 near the stylar end of the lemon (pi. 7, E and F). Affected tissues 

 become pinkish or brownish in color. One-fifth to one-half of the 

 interior of the lemon may be involved in extreme cases, but such 

 fruits are practically certain to be culled out in packing operations. 

 The disease is not known to develop after harvest, but it renders the 

 fruit more susceptible to decay, especially that caused by Alter- 

 naHa (Ji3). 



On green fruit the presence of the disease may be indicated exter- 

 nally by a loss of luster or the development of a yellow color at the 

 stylar end while the rest of the surface is still a normal green. On 

 either ''silver*' or mature fruit it is difficult to detect internal decline 

 from outward appearance, especially in mild cases. Sometimes there 

 are a more intensive coloring of the rind at the stylar end and a col- 

 lapse of the tissues at the base of the nipple that causes it to bend over. 



