Florida Agricultural Experiment Station


results (Fig. 7). Fruits moderately to heavily infected by mel-
anose have a rough, sandpaper-like surface, the rough russeting
being termed "rust" by some growers. In severe cases of in-
fection the fruit may be dwarfed and, where badly scarred, may
crack open as it approaches maturity.


Fig. 2.-Portion of grapefruit leaf showing character of mature melanose
 spots. (Twice natural size.)
 CAUSE OF MELANOSE
 Melanose was shown by Stevens, in 1912, to be due to Pho-
mopsis citri Fawcett, the same organism that produces one of
the stem-end rots of citrus fruits in Florida. In 1926, Wolf
reported the finding of the perfect, or ascospore, stage of this
fungus occurring on dead citrus twigs lying on the ground and
named it Diaporthe citri. The minute, pustule-like fruiting bodies
of the fungus develop abundantly on recently dead twigs and
fruit stems. The life-cycle of the fungus appears to be completed