Oct. 29, 1921 Physiological Study of Grapefruit Ripening 275 



this pitting was worked out the storing of grapefruit for any considerable 

 period would hardly be commercially practicable. 



Experiments were, therefore, undertaken to see if it were possible to 

 treat or handle the fruit so that it could be cold-stored without this danger 

 of pitting. As was mentioned earlier, fruit stored in warm storage, 70° 

 to 86° F., or in common storage (about 55° to 60°) apparently does not 

 pit. It was considered possible that if fruit were cured for a time in warm 

 storage before being placed in cold storage the injury from this blotching 

 and breaking down of the surface of the peel might be obviated. Ac- 

 cordingly a lot of I dozen fruits from tree i , third pick, was maintained at 

 a temperature of 70° and a humidity of about 65 per cent for one month, 

 then removed to cold storage (32°) and xamined at intervals. At the 

 end of three months in cold storage none of these fruits were pitted, while 

 about 60 per cent of the fruit from the same lot olaced directly in cold 

 storage at 32° were badly pitted. 



The experiment was repeated with grapefruits of the Duncan, Marsh 

 Seedless, and Silver Cluster varieties from Polk County, Fla., which were 

 placed in storage February 12, 1920. Part of the fruit of each lot was 

 placed directly in 32° F., and the rest of the three lots were placed in the 

 curing room and maintained at a temperature of about 70° with a relative 

 humidity around 60 per cent. Portions of the lots from the curing room 

 were removed to 32° cold storage at intervals. The entire storage period 

 was three months for all lots. The results of the experiment are shown 

 in Table IV, in which are given the length of time in curing, the time in 

 cold storage, and the percentage of pitting of the different lots. In 

 these experiments the pitting is given as slight and bad pitting. Bad 

 pitting is applied to pitting that would markedly injure the sale of the 

 fruit. Slight pitting refers to pitting that while noticeable does not par- 

 ticularly injure the fruit for sale. It is at most a few spots usually small. 



It is noticeable in Table IV that most of the control fruit that was 

 placed directly in cold storage without curing is pitted and that there is a 

 high percentage of bad pitting. In the Duncan, 6 per cent was good, 

 while the poorest lot of cured fruit of this variety was about 90 per cent 

 good. There was more pitting in the cured Silver Cluster than in the 

 Duncan and somewhat more in the Marsh Seedless than in the Silver Clus- 

 ter. The data obtained in this one storage experiment are hardly suffi- 

 cient, however, to justify the conclusion that Duncan grapefruit store 

 better than Silver Cluster and Marsh Seedless. The experiments, how- 

 ever, seem to show that the pitting can be controlled by proper curing 

 before the fruit is placed at the low temperatures. The specific effect of 

 this curing, by exposure to warm temperatures from one to six weeks, 

 on the tissue of the peel so that the pitting is prevented has, of course, 

 received little attention. Pitting has all the external appearance of 

 injury considered to be due to Colletotrichum gloeosporioides (Penz.) by 

 Rolfs, Fawcett, and Floyd (zj) and figured by them. This fungus, 



