Bulletin 229, Diseases of Citrus in Florida


considerable progress within the fruit, in which case it becomes
discolored over the affected interior. The exterior light-brown
to blackish discoloration usually is confined to a limited portion
near, and usually at one side of, the navel or stylar end. The fun-
gus evidently exerts a stimulating effect upon the physiological
processes of the fruit and, even though the diseased portion of
the orange is small, the whole orange develops a high color pre-
maturely.


Fig. 58.-Black rot of orange. Sectional view showing extent of the decay.

 When an infected orange is cut in half lengthwise the full
extent of the rot becomes apparent. Underneath the brownish
or dark-colored spot the tissue is brown or, in more advanced
stages of the decay, greenish-black. The blackening may extend
through the central portion of the fruit (Fig. 58). This decay
does not soften the fruit as rapidly as other rots and is confined
more to the interior of the fruit. In some cases there is no vis-
ible sign on the exterior to indicate that black rot is present.