CITRUS MELANOSE AND ITS CONTROL 6 
affected areas usually persist throughout the life of the fruit, but in 
some instances the brown rough tissue has a tendency to slough off, 
particularly in the " mud-cake " type. 
EFFECT ON TWIGS 
The infection on twigs (pi. 5, A, B) appears at first very much as 
it does on the leaves, and later the spots, if few in number, become 
much more raised than on leaves or fruit and in some instances re- 
semble forms of die-back. If the infection is severe, " mud-cake " 
patterns (pi. 5, C) are likely to develop, and the twig dies. One of 
the distinctive features of the disease is the presence on water sprouts 
of two or three zones of very severe melanose infection, between 
which are zones comparatively or entirely free from these blemishes. 
These zones represent infection and noninfection periods during the 
growth of the water sprout. 
DISEASES CONFUSED WITH MELANOSE 
A number of blemishes are commonly confused with citrus 
melanose. 
AMMONIATION 
Ammoniation is considered to be a form of die-back, a common 
nutritional disease of citrus. These blemishes are rare on grapefruit, 
but on oranges they may be confused with melanose although totally 
different as to origin. (PL 6, A and B.) When the two occur on the 
same fruit it is difficult to distinguish between them in the field, on 
either mature or immature fruit, especially so when the two types 
occur in slight to moderate amounts. Ammoniation spots on the 
orange are larger, more erumpent, and usually when raised are of a 
lighter brown color than melanose. When these spots are examined 
under a hand lens, minute cracks may be found on the raised parts. 
These spots are usually glazed by a resinous excretion, and beneath 
them minute gum pockets or gum-filled areas are usually present; in 
very severe cases gum deposits may be found even in the central 
pulpy axis of the fruit. 
STAR MELANOSE 
Star melanose is a false melanose with raised dark-brown to black 
excrescence having irregular margin with from three to five or more 
points. (PL 7, D.) These spots range in diameter from 1 to 3 milli- 
meters and occur more frequently on the surface of leaves than on 
fruit. They have been observed by the writers only on trees that 
previously had received applications of Bordeaux mixture or Bor- 
deaux-oil emulsion, which suggests that they are probably due to 
spray injury. 
BLACK MELANOSE 
Black melanose is a spotting of citrus leaves which, although not 
similar to citrus melanose in appearance, causes considerable con- 
fusion because of the similarity of names. Black melanose appears at 
first as a yellowish green discoloration on orange and grapefruit 
leaves. These spots soon become distinctly raised on both surfaces, 
owing to an accumulation of resinous material in the affected area, 
