18 MISC. PUBLICATION 4 98, U. S. DEPT. OF AGRICULTURE 



of the surface are usually involved the name "scald" has often been 

 used for this trouble. These areas are sunken, having distinct and 

 abrupt margins, and vary in color from tan through rusty pink to deep 

 brown (pi. 1, E). Oil vesicles in the affected area are not as promi- 

 nent as with oil spotting. Only the outer part of the rind is affected, 

 so that unless the fruit is severely spotted the flavor of the juice is not 

 affected. The spots afford entrance to decay-producing organisms, 

 such as those causing blue mold rot, black mold rot, and sour rot. 



Eind break-down may result from several causes. Limes stored at a 

 temperature of 40° F. or lower are more subject to the spotting than 

 those held at 45° or above, although when held at the higher tempera- 

 ture for periods of 8 weeks or longer they usually develop some of the 

 trouble. At low temperature the injury is more severe on immature 

 than on riper fruit. Limes stored in a dry atmosphere are more sub- 

 ject to rind break-down than those held under moist conditions. Some 

 of the spots undoubtedly result from rough handling during packing 

 and shipping. 



Control measures consist of careful handling, prompt shipment, and 

 storage at temperatures between 45° and 48° F. and relative humidities 

 above 85 percent. 



(See 122.) 



STEM-END ROT 



(See Grapefruit, Stem-end Rot, p. 7, and pis. 5, A, and 6, A.) 



STYLAR-END BREAK-DOWN 



Tahiti (Persian) limes as they approach maturity either on the tree 

 or after picking are susceptible to a collapse of the rind at the 

 stylar or blossom end of the fruit. Frequently in shipments containing 

 fruit of the "turning" stage of maturity, from 5 to 10 percent are af- 

 fected. Limes that are apparently sound when packed may become 

 badly affected during a 4-day transit period. During the summers of 

 1937, 1938, and 1939 stylar-end break-down was the most important 

 transit disease of this fruit from Florida. The disease has been noted 

 occasionally on Key (Mexican) limes and on lemons. 



Usually the disease appears first at the base of the nipple or tip as a 

 grayish tan, water-soaked spot. The affected area enlarges rapidly 

 involving the stylar end up to one-third or one-half of the fruit. Oc- 

 casionally the disease appears at the stem end as well as at the stylar 

 end. The affected area remains firm but becomes darker with age and 

 usually sinks below the healthy surface. There is often a partial col- 

 lapse of the flesh within the stylar end of the fruit and a water soaking 

 of the core tissue. The affected rind is quickly invaded by organisms 

 such as Oospora, Aspergillus, and Colletotrickwm. 



Since in early stages no organism has been found associated with the 

 disease, it is considered physiological in nature. The only control 

 measure that can be recommended is picking the fruit before it becomes 

 too mature. 



(See^,£0.) 



Oranges 



aging 



The term "aging" is used in referring to the condition sometimes 

 found after harvest on citrus fruit, chiefly oranges and grapefruit, in 



