Bulletin 229, Diseases of Citrus in Florida


 5. Picking the Fruit Shortly After Maturity:-Since the va-
rious varieties of citrus fruits are more liable to develop stem-
end rot if held too long after they are ripe, it follows that pick-
ing and shipping the fruit as soon as possible after it attains
maturity is one of the best and most practical methods for con-
trolling this form of decay.
 6. Precooling and Refrigeration:-The amount of stem-end
rot to be expected after picking is largely influenced by the tem-
perature at which the fruit is held, the development of both
the stem-end rots being greatly favored by high temperatures.
Diplodia stem-end rot shows up most rapidly in fruit that is held
above 750F., while Phomopsis stem-end rot makes its best de-
velopment at temperatures between 65' to 750F. Winston, Ful-
ton, and Bowman have shown that, by promptly cooling the
fruit to from 450 to 500F., stem-end rot can practically be pre-
vented over a 3-weeks' marketing period in fruit that would show
a 20 to 30 percent loss in the same time at temperatures above
700F. An analysis of the market reports shows that the great-
est amount of loss from stem-end rot consistently occurs both
early and late in the shipping season, when the weather is warm.
Therefore, the importance of promptly cooling the fruit after
picking late, especially during warm weather, is evident. Every
day the fruit is exposed to a high range of temperatures, especi-
ally from 700 F. or above, lessens by several days the average
life expectancy attainable at low temperatures.
 7. Promptness in Handling:-Each type of stem-end rot is
 peculiar in that its development is long drawn out in any one lot
 of fruit. A particular fruit may remain entirely sound for many
 days or weeks and then suddenly develop the first symptoms
 of stem-end rot. For example, shipping tests of Florida oranges
 from groves in three different localities, conducted in 1911 by
 Fawcett in cooperation with the U. S. Department of Agricul-
 ture, showed an average of 1.5 percent of stem-end rot upon ar-
 rival at the market, 8.5 percent one week later, 22.3 percent two
 weeks later, and 36.7 percent three weeks later. It will thus be
 seen that whatever can be done to shorten the average length
 of time of getting the fruit from the tree to the consumer will
 lessen by so much the aggregate loss from stem-end rot, especial-
 ly in warm weather. Delay in packing, too long hauls to market,
 delay in transit, and overstocking by dealers should be avoided
 as far as possible.