CITRUS MELANOSE AND ITS CONTROL. 13 
TREE INJURY 
The injury to trees resulting from a slight leaf infection is usually 
of no special consequence, but severe infection frequently causes a 
crinkling of the leaves (pi. 1, A and B) which impairs their function, 
and in the more severe outbreaks defoliation and killing back of twigs 
(pi. 2, A) result. This severe injury is likely to develop in the 
spring and summer following frosts or freezes that defoliate and 
kill twigs. When this blighting occurs in quantity the prospect for 
a heavy crop the following year is unfavorable. Obviously the finan- 
cial losses resulting from such a form of injury are difficult to 
estimate. 
FRUIT BLEMISH 
Melanose blemishes on fruit (pi. 4) are responsible for a tangible 
financial loss, as is shown by the reduction in the market value of 
fruit bearing melanose markings. A fruit with a moderate amount 
of melanose is usually packed in the second or third grade, but a 
severely blemished fruit is a cull, and therefore has no market value. 
Severe melanose infections may even cause the dropping of fruits 
iy 2 inches or less in diameter, but this melanose-induced drop occurs 
in quantity rather infrequently. 
FRUIT DECAY 
Stem-end rot, caused by the melanose fungus, is responsible for 
fully 40 per cent of the decay of Florida oranges and grapefruit in 
transit, on the market, or in the consumer's home. This phase is 
not to be discussed in this bulletin, but is mentioned simply to call 
attention to the potential importance of melanose and its usual 
sequel. There is also an important stem-end rot of Florida citrus 
fruits caused by Diplodim nato&ensis Pole Evans. 
In 1922 the State of Florida produced more than 25,000,000 bushels 
of oranges and grapefruit. Fully 15,000,000 bushels of those bore 
melanose blemishes to a greater or less degree, and at least 1,000,000 
bushels were scarred by this disease in sufficient proportions to cause 
them to be packed in the third grade or lower, or even disposed of as 
culls by those who put up a carefully graded pack. 
The importance of this disease in nurseries and young groves is 
usually not great, but following damaging frosts or other conditions 
which tend to increase the amount of deadwood, melanose may do 
considerable damage to new shoots. Therefore it is plainly evident 
that the melanose fungus is not only potentially capable of causing 
enormous losses but actually does cause these heavy losses. With the 
citrus crop of Florida increasing rapidly, it is only reasonable to 
assume that the losses attributable to the fungus Phomopsw citri, 
namely, melanose and stem-end rot, will likewise increase unless spe- 
cial measures are taken to prevent them. 
Although this blemish reduces the sale value of the fruit, the taste 
is not noticeably altered, but fruit bearing melanose scars is more 
likely to decay ultimately from stem-end rot than fruit free from 
such blemishes. 
