CITRUS FRUITS 123 



Hawaii, Australia, Southern Europe, and no doubt in 

 many other countries where the citrus fruits are grown. 

 It is known by many common names, such as " morfea," 

 " fumago," "Nero," and " mal di cenere" in Italy; 

 " sooty mould " in the United States ; " sooty mould," 

 "fumagine," "black mildew," and "black blight" in 

 Australia. C. Stella turn, Bernard, has been reported on 

 the citrus fruits in the Dutch East Indies. 



These fungi are not parasitic upon the orange, but 

 are saprophytes belonging to the pyrenomycetes, and 

 living upon the honey-dew which is exuded by many 

 insects belonging to the families Aleyrodidae, Coccidae, 

 and Aphidiaae. These insects occur not only upon the 

 orange but upon many other plants. The fungus grows 

 rapidly and covers the leaves, stems, or fruits with 

 masses of black mycelium. In fact, it is frequently so 

 abundant that the trees have the appearance of being 

 painted black. While the fungus does not feed upon 

 the tree itself it covers the parts so completely that the 

 leaves are prevented from performing their normal 

 functions, and reduces the vitality and productiveness 

 of the plant. It also seriously injures the fruit for 

 market. Since this disease, if it can be called a disease, 

 is dependent on the insect, the treatment should be one 

 that will destroy the insects. 



Melanose. This disease has been reported from 

 Florida, Australia, and Cuba. It occurs on the leaves, 

 fruit, and twigs, producing small brownish - black 

 elongated spots. The leaves fall rapidly, and the 

 normal functions of the trees are greatly reduced. No 

 organism has been found which will account for the 

 disease, but it responds readily to treatment with weak 

 Bordeaux. The first spraying should be given before 

 the trees bloom, and the other applications about once 

 a month until the fruit is well formed. The use of 

 potash manure, and the avoidance of fertilisers rich in 

 nitrogen, has been recommended. 



Lichens. These plants frequently grow abundantly 

 over the trunk and branches of the trees, and sometimes 



