Florida Agricultural Experiment Station


 CHARCOAL ROT OF LIMES
 Probably caused by Diplodia natalensis Evans.
 This form of decay was observed by Wilson in 1918 on
Florida limes in the northern markets and was reported by
Nowell in 1923 to occur on West Indian oranges bought in Bar-
bados. On the fresh fruit the trouble is recognizable by the ap-
pearance of smooth, somewhat discolored areas, varying from a
deepened yellow to copper color, with the margins mostly brown-
ish. The spots later turn brown and, finally, black. This spot-
ting quite often involves the whole fruit. An abnormal color
and odor are found upon opening the diseased fruits. The limes
eventually become black inside and, after becoming dry and
mummified, are found to be filled with black, hardened masses
of fungous growth. This lime decay has been termed charcoal
rot by Wilson, who first studied it. He isolated a fungus which
developed a coal-black mass but did not develop fruiting bodies.
Pure cultures of the isolated fungus reproduced the decay, how-
ever. Because of the lack of knowledge concerning the fruiting
bodies, the causal organism was not identified by Wilson. Faw-
cett and Burger have each subsequently obtained a Diplodia from
limes affected by this decay. Fawcett is of the opinion that the
fungus which Wilson isolated was a Diplodia which failed to
fruit. Lemons frequently develop this type of decay in Florida,
following attack by the Diplodia fungus, and often mummify on
the trees.
 ASPERGILLUS ROT
 Caused by Aspergillus niger Van Tiegh.
 A minor form of soft decay, due to this common mold fungus,
occurs occasionally on citrus fruits. This decay starts as a light-
colored, very soft, easily punctured spot very similar in its
initial stage to the decays caused by the common blue or green
mold fungi. The causal fungus fruits readily, developing pow-
dery, brownish-black spore-masses within a short time on the
rotted areas (Fig. 60). It does not appear capable of rotting
citrus fruit readily except where the fruit is held at fairly high
temperatures. Injuries to the fruit are the most common means
for this mold fungus to gain entrance. This fungus was recently
observed in Florida, developing in the stylar end of calamondin
fruits while on the tree.