Bulletin 229, Diseases of Citrus in Florida


and other succulent shoots is frequently so severely attacked
that it is permanently distorted (Fig. 3).
 On the Twigs:-The disease on the twigs (Fig. 4) appears at
first very much as it does on the leaves but the minute corky
outgrowths ultimately become more raised than on the leaves
or fruits. If the infection
is severe, the twigs may
become more or less com-
pletely covered by scar
tissue and may die.
 On the Fruit:-Lesions
 on the fruit (Fig. 5) are
 similar to those on the
 leaves. They are at first
 dark and sunken, later be-
 coming brown, distinctly
 raised, and rough to the
 touch. When the infec-
 tion is slight, the mela-
 nose spots are usually
 scattered, raised specks
 ranging from 1/50 to 1/25
 inch in diameter. They are
 round and dark brown in
 appearance, resembling
 minute drops of burned
 sugar. If the infection is
 more severe the melanose
 specks are much more
 numerous and sometimes
 closely resemble the erup. Fig. 1.-Early stage of melanose on
 tions resulting from exan- grapefruit leaf, showing the yellow-
 thema ammoniationn). As bordered spots.
 on the other susceptible parts, however, the spots may form lines,
 curves, circles, and other patterns. They sometimes appear in
 tear-streaked patterns (Fig. 6) resulting from infections caused
 by spores being washed down over the fruits by drops of water.
 In other cases, a solid scar tissue, roughened, or with a "shark-
 skin" effect, may involve a large part, or even all, of the fruit.
 Where shallow cracks of more or less regular pattern develop
 in this superficial scar tissue the "mud-cake" type of melanose