MARKET DISEASES OF FRUITS AND VEGETABLES 9 



45° are as necessary for control of stem-end rots in transit as for 

 green mold and blue mold rots. In storage, 32° to 34° is desirable for 

 all of these rots. _ 



Marked reduction in the percentage of phomopsis and diplodia rots 

 after the fruit is harvested has been obtained by treating the fruit 

 with a borax solution before it is packed. The treatment consists 

 in submerging the fruit in an 8- to 10-percent solution of borax (139) 

 and then allowing it to dry. The borax residue should be left on 

 the fruit for several hours before it is washed. Heating the solution 

 to about 120° is necessary to keep the borax in solution and make it 

 more effective. 



Disbuttoning is also beneficial, because it removes the source from 

 which infection spreads into otherwise sound fruit. Pulling grape- 

 fruit instead of removing it with clippers is beneficial for the same 

 reason and is now extensively practiced in Florida. Oranges cannot 

 safely be harvested by pulling because of the danger that the rind 

 around the button will be plugged (torn). 



Pruning out dead limbs and twigs to diminish the sources of in- 

 fection is a helpful measure and has the further advantage that it 

 tends to decrease the melanose spotting of immature fruits caused by 

 Phomopsis citri. 



(See 6, 10, 23. 27. 28, 38, 41, 4%, Jfl, 52, 61, 64, 96, 109, 110, 111, 112, 

 138,139,140,141,143.) 



STYLAR-END ROT 



(See Oranges, Stylar-end Rot, p. 32, and pi. 13, E.) 



SUNBURN 



There are sometimes seen, on grapefruit and oranges, large areas 

 that are pitted all over, hard, and much yellower than the rest of the 

 fruit surface. The pits are very small and apparently have resulted 

 from collapse of the oil cells. In the lots of fruit that show various 

 degrees of more severe injury the stages seen may be yellow hard 

 spots, or similar spots with a brown patch near the center or with 

 a gray patch at the center surrounded by a brown zone, the gray 

 patch (y 2 to iy 2 inches in diameter) sometimes with either very small 

 black specks (the fruiting bodies of some fungus) or a black velvety 

 fungus growth over the whole surface. Occasionally the gray area 

 becomes softened and may be encircled by a brown to dull salmon- 

 colored diseased zone. What appears to be the final stage consists of 

 a large, softened diseased area, which is a dull salmon color all over 

 and is surrounded by a hard, yellow, pitted zone. 



The occurrence of spotting of this kind, known as sunburn, is 

 probably due to injury by hot sunshine acting alone or in combination 

 with drops or films of spray mixtures adhering to the fruit, and to 

 subsequent infection by one or the other of two stem-rot fungi (Pho- 

 mopsis and Diplodia) or more probably by Colletotri-chum. It is pos- 

 sible that the spotting sometimes results from severe drenching of the 

 fruit with a spray mixture, without any contributory action by 

 sunshine. (See also Oranges, Spray Injury, p. 32.) 



The later stages, showing rather soft decay, would not ordinarily 

 be found in packed fruit on the market unless the grading and packing 

 had been carelessly done. 



