Tropical Fruits 



143 



are at first yellowish, l)ut as the disease advances they become 

 almost black, antl finally crack open. 



Ammoniacal copper carbonate or Bordeaux mixture will 

 prevent scab. 



Anthracnose, wither-tip {CoUetotrichum glaeosporioides 

 Penz.). — In this disease the leaf spots are circular in out- 

 line, yellowish in color, and bear the small dark filaments and 

 spores of the causal fungus. 

 Terminal twigs shed their 

 leaves and die. 



The disease also occurs 

 upon the fruit of various 

 citrus trees. Rolfs noted 

 its attack upon the lemon, 

 where it caused the fruit 

 to fall prematurely, and 

 Hume reports that it may 

 occur upon the pomelo 

 either before or after 

 the fruit is picked. The 

 brownish spots enlarge with 

 age and become dirty 

 black in color. The fun- 

 gus invades the interior of 

 the fruit as well as the rind. 



In all cases the diseased parts should be cut out, care being 

 taken to cut far enough back to remove all injured parts; 

 also affected fruits should be removed and destroyed. Spray- 

 ing with Bordeaux mixture controls the disease upon the 

 fruit. 



Root-rot (Phijtophthora terrestria Sherb.). — The first symp- 

 toms are abundant exudations of gum upon the trunk of the 

 tree; at the same time the bark develops brownish patches, 

 which are thrown off, followed ])y other patches. The tree 

 appears to lack nutrition, the leaves becoming yellow, scanty, 

 and small. Though the trees heav considerable fruit, the 

 amount of damage in Florida was estunated in 1896 to be 



Fig. 75. — Orange leaves showing 

 spots caused by anthracnose. Af- 

 ter Hume. 



