28 CIRCULAR NO. 124, BUREAU OF PLANT INDUSTRY. 



would tend to strongtlien the evidence aiTorded l)y the former ex- 

 periment in making it aj^pear wortli while to precool oranges for 

 transportation when they are taken from groves which yield a high 

 percentage of decay. 



SUMMARY AND CONCLUSIONS. 



These preliminary experiments are too small and few to permit 

 any but tentative conclusions, yet the results are so clear cut and 

 uniform in regard to some of the significant points that they may be 

 specially noted. In the first place, it should be borne in mind that 

 the condition of the fruit at maturity is a resultant of the environ- 

 ment of the grove during the growing season. Coincident with the 

 uncommonly wet season of 1912 melanose and ammoniation of the 

 fruit were prevalent over most of the citrus region of Florida, and it is 

 very probable that the wet weather was directly related to the occur- 

 rence of such rind injuries. The excessive moisture of both the soil 

 and the air in connection with these injuries resulted in numerous 

 splits and rind distentions, which caused an enormous development 

 of mold in the groves. The presence of large numbers of stinkbugs^ 

 which suck juice fi'om oranges, probably also added to the epidemic 

 by inoculating sound fruits when inserting their beaks through 

 portions of rinds on which the air currents had deposited mold spores- 

 The rather muggy warm weather prevailing in late November and in 

 December doubtless also contributed to the heavy decay of that time, 

 for these experiments indicate that temperatures no lower than 15° C. 

 (60° F.) practically prevent the development of the mold rot. 



But in addition to the mold-rot epidemic induced by the split and 

 cracked rinds, much fruit dropped and decayed which was not split. 

 The above results make it appear probable that Phomopsis citri 

 was responsible for most of the rot of that type except w^hat was due 

 to bug-puncture infections. This also agrees with the fact that 

 melanose was very abundant in the districts where much fruit de- 

 cayed. However, the scarcity of phomopsis pustules on the dead 

 twigs during late fall and winter argues that this fungus may sporulate 

 elsewhere or that its mycelium persists in some melanose spots on the 

 stem or calyx of the fruit. 



Perhaps the most important conclusion that these observations 

 force upon us is the importance of growing fruit that is free from 

 melanose and thus not only obviating a reduction in the market 

 value of the fruit but also preventing some splits and most of the 

 stem-end rot. The fact that the refrigerator temperature used in 

 these experiments ])ractically prevented all decay suggests tliat 

 shipping tests should be made with precooled fruit in refrigerator cars 

 and boats. 



ICir. IL'4] 



