118 Florida Agricultural Experiment Station

be emphasized too strongly, however, that chemical treatments
of citrus fruit cannot be expected to eliminate the need for care-
ful handling to prevent injuries.
 5. Precooling and Refrigeration:-Blue mold develops to best
 advantage at temperatures ranging from about 550 to 650F.
 In general, temperatures of 400 to 450F. are best for controlling
 the two types of mold decay. This range is lower than that re-
 quired for stem-end rot control. Precooling and refrigeration
 of the fruit accomplish this purpose very effectively.
 The principle that requires emphasis above all else is the ne-
 cessity of carefully handling the fruit to avoid injuries during all
 operations from the grove to the consumer.
 STEM-END ROT
 Caused by Phomopsis citri Fawcett and
 Diplodia natalensis Evans
 Certain species of fungi are capable of producing pliable,
 leathery decays which usually begin at the cut stem- or "button"-
 end of the fruit. Decays of this type are generally termed
 "stem-end rots". Stem-end rot was first studied and reported in
 Florida by Fawcett, being discovered in 1909. The disease was
 later found to occur throughout the whole citrus-growing region
 of the state. The organism which causes this disease was iso-
 lated and described by Fawcett in 1912 as Phomopsis citri. Pho-
 mopsis stem-end rots of a similar nature have since been re-
 ported on citrus fruits in Cuba, Isle of Pines, Porto Rico, and
 Brazil, and on lemons from California and Sicily.
 In 1911, 1912, and 1913, Fawcett studied a very similar form
 of stem-end rot of grapefruit and oranges in Florida, caused by
 Diplodia natalensis. This fungus was originally described in
 1910 by Evans in connection with the decay of lemons in South
 Africa. The same, or a similar species of Diplodia, also pro-
 duces a stem-end rot of citrus fruits in Cuba, Porto Rico, Cali-
 fornia, and the Philippines.
 The Phomopsis and Diplodia stem-end rots are factors of great
 importance in the shipping and marketing of Florida citrus
 fruits. The great majority of the stem-end rot occurring in
 Florida citrus fruits is caused by the Phomopsis fungus, which
 likewise causes melanose. Winston, Bowman, and Bach esti-
 mated that this form of stem-end rot is responsible for fully 40
percent of the decay of Florida oranges and grapefruit in transit