6OO RUBBER 



into small fragments by lines more or less at right angles 

 to each other. 



In Ceylon pink disease usually makes its appearance 

 towa'rds the close of the rains of either monsoon. As a 

 rule, treatment is confined to pruning down the tree below 

 the diseased part. In South India, spraying the forks of 

 the trees with Bordeaux mixture has been found to 

 prevent attack. 



The term " dieback " might equally well be applied to 

 some cases of pink disease, since in the latter the whole 

 of the crown above the diseased part of the stem may 

 die. The name has, however, become associated with a 

 different disease, in which the whorls of branches die in 

 succession from the top downwards, owing to the growth 

 of a fungus down the main stem. 



The chief agent in dieback that is, the fungus which 

 kills the main stem is Botryodiplodia theobromse. It 

 occurs throughout the tropics, but is especially common 

 in cocoa-growing countries. As usual, it has received a 

 number of names, among which may be noted Lasio- 

 diplodia theobromx, Lasiodiplodia nigra, Diplodia 

 cacaoicola, Diplodia rapax, Botryodiplodia elastic^. 

 Though numerous diseases have been attributed to this 

 fungus, it is, in general, a saprophyte. It develops in 

 abundance on plucked cocoa pods, felled Hevea stems, 

 stems of Ficus, etc., though these may have been quite 

 healthy when living. It is only necessary to gather cocoa 

 pods or to fell a sound Hevea stem and to leave it to 

 dry, either under cover or exposed to rain, to obtain this 

 fungus. In about a week the material will be covered 

 with masses of spores in the form of a black powder. If 

 the material is somewhat dry the spores may be white at 

 first, turning black subsequently. 



Botryodiplodia theobromse can, however, function as a 

 wound parasite, and in that capacity it may attack Hevea 

 and cocoa. In the case of Hevea, once it has obtained 

 entrance to the stem it travels rapidly downwards, and 

 may kill the tree completely within four or six weeks. 

 The wood of the stem is blackened by the hyphae of the 

 fungus, the cambium is converted into a brown slimy 

 layer, and the bark splits away from the wood and 

 dries up. 



