118 DISEASES OF TROPICAL PLANTS on, 



parts attacked become light green in colour and event- 

 ually brown. The light brown or nearly black acervuli 

 or fruiting bodies are next formed upon either side of 

 the leaf. The leaves wither and die, and the disease 

 gradually travels back along the new growth causing 

 the characteristic " wither-tip." These injured parts 

 frequently break and hang lifeless, having much the 

 appearance of having been cut by insects. Young 

 trees are sometimes entirely defoliated in this mariner. 

 It can readily be distinguished from the blight by the 

 fact that the leaves do not wilt, and from the dieback, 

 by the absence of dark excrescences, of gum pockets, and 

 multiple buds. 



The opening blossoms expose the stigma, which is 

 the most vulnerable point of the plant. The blossoms 

 and young fruit which are attacked in this manner fall 

 very early, and frequently the entire tree is left fruitless. 

 If the bloom escapes, the young fruits may be attacked 

 at almost any period of their development. They 

 sometimes have the appearance of having been bitten 

 by insects and usually fall very early. When about 

 half grown the fruit becomes more resistant to disease 

 and either throws it off entirely or forms a corky scar 

 over the surface. However, the fully matured fruits are 

 frequently attacked as the result of abrasions in hand- 

 ling, through which the fungi gain entrance. In these 

 cases the fruits may be entirely destroyed or their value 

 may be greatly reduced. Infected fruits, which show 

 no indications of the disease, are frequently shipped but 

 develop the disease before they can be put on the retail 

 market. This is especially true of the lemons. 



It has a very wide distribution, having been reported 

 from the United States, Cuba, Porto Eico, Jamaica, 

 Brazil, Mexico, Australia, 1 Italy, and Malta, In all 

 probability it occurs in all citrus-growing countries of 

 the world, although it may be very much more severe 

 in some places than in others. 



The diseased fruits, leaves, and twigs should be 



1 Another anthracnose of Australia is caused by Phoma citricarpa, M 'Alpine. 



