14 BULLETIN 63, U. S. DEPARTMENT OF AGRICULTURE. 
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 fruit, the investigations were bo 
planned as to determine whether it was practicable to handle the fruit with sufficient 
care to prevent injury. 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 deter mi ne 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-mold 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 citru s 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 within 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 fungu3 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 f ungus 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 
