14 BULLETIN 63, U. S. DEPARTMENT OF AGRICULTUEE. 



thin-skinned, juicy fruit. The necessity of handling with extreme care so perishable 

 a product as the Florida orange can not be too strongly emphasized. 



After the determination of the character of work being done and the discovery that 

 considerable injury was being inflicted on Florida fi'uit, the investigations were so 

 planned as to determine whether it was practicable to handle the fruit with sufficient 

 care to prevent injiury. At first demonstrations corresponding to those carried on in 

 California were made in the packing houses, using fruit selected for soundness and 

 similar lots showing injuries of various kinds. The effects of dropping the fruit and of 

 washing it to remove sooty mold were also demonstrated. These lines of work proved 

 conclusively that blue mold develops wherever the skin of the orange is injured in any 

 way, and that dropping is followed by serious decay, especially when the fruit falls 

 into a receptacle containing dry twigs, gravel, splinters, or other matter rough enough 

 to bruise or puncture the skin. 



After the packing-house demonstrations, showing that sound, uninjured Florida 

 oranges are not affected with blue-mold decay, shipping experiments under com- 

 mercial conditions, were undertaken. These experiments consisted of forwarding 

 boxes of fruit of known history to Washington, where the percentages of decay were 

 carefully determined on the day of arrival and after one, two, and three weeks, the 

 fruit meantime being held under ordinary open-market conditions. 



These experiments were followed during five successive seasons, thus enabling the 

 investigators to determine the effect of seasonal influences. The data obtained during 

 1910-11 and 1911-12, when the work was undertaken on a more extensive scale than in 

 the former seasons, corroborated the early results without exception, and the carrying 

 quality of the Florida orange when packed and shipped in sound condition was 

 proved to be as good as that of the California product. An injured orange, whether 

 grown in California or in Florida, will decay whenever the conditions for the develop- 

 ment of blue mold are favorable. A sound orange in good, healthy condition, whether 

 grown in California or in Florida, is able to resist blue-molcl decay. 



BLUE-MOLD DECAY OF THE ORANGE. 



Indications of decay. — The characteristic appearance of the orange decayed by blue 

 mold is too well known to need description. Every handler of citrus fruits knows blue 

 mold, which is by far the most common form of decay. The grower frequently sees it 

 in the oranges hanging upon the trees, when the fruit has split or has been injured by 

 thorns or twigs. He finds it in the fruit which has dropped to the ground. The packer 

 sees it in the cull pile or in the boxes of fruit left standing in the house for a few days. 

 The receiver of the fruit finds the decay as the boxes are opened, and frequently he 

 smells it before removing the covers. 



The first indication of decay is a small area of soft tissue at some point on the surface 

 of the fruit. This increases rapidly in extent if the weather is moist and warm, and 

 within a day or two a bluish or greenish spot develops. If weather conditions continue 

 favorable, the entire fruit is rotted witliin a few days, and the surface is generally coated 

 with a bluish or greenish blue mat or powdery covering. 



BLUE-MOLD FUNGUS. 



Blue-mold decay is caused by the growth of a minute organism within the tissues 

 of the fruit. Laboratory experiments have shown this organism to be a fungus of the 

 genus Penicillium, which includes the familiar blue mold or mildew on bread, on the 

 surface of canned fruit, and on other vegetable matter. Growth takes place within 

 the orange, the bluish mat on the skin being composed of the fruiting bodies made up 

 of chains of spores, massed together in great numbers. The fungus is spread by means 

 of these spores, which, like the seeds of many higher plants, germinate and grow as 

 soon as they find lodgment under conditions favorable for their development. They 



