RUBBER 193 



part or all of the tree. The bark cracks and peels, expos- 

 ing the fungus as a blackish fur on the surface of the 

 wood. The mycelium is brown in colour, branching, 

 and, after killing the bark, penetrates the young wood, 

 which soon becomes dark. It is not often serious, but 

 it sometimes kills the tree, and frequently reduces the 

 flow of latex. It can be controlled by cutting and 

 burning the diseased parts, painting the wounds, and if 

 very severe by spraying with Bordeaux mixture. 



Stem Disease. A stem disease of the Para rubber, 

 due to Diplodia rapax, has been reported from the 

 Federated Malay States. It attacks the younger shoots, 

 causing them to turn black and die. It gradually 

 spreads downward until the trunk becomes affected and 

 dies. After a time many raised spots appear, and the 

 bark splits, thus exposing the black perithecia embedded 

 in a stroma. 



Another bark disease which is caused by Eutypa 

 caulivora, Massee, occurs on the Para rubber in the 

 Malay States. It is very similar to the bark disease of 

 the cacao and nutmeg which is caused by E. erumpens, 

 Massee (see page 187). 



Dieback. - - This is a disease of the Para rubber 

 which has been reported from Ceylon and the Federated 

 Malay States, and probably occurs in other places. It is 

 said to be due to Thyridaria tarda? which also attacks 

 the cacao. It causes a dying back of the young shoots 

 which may eventually reach the trunk and roots and 

 cause the death of the tree. Although the fungus is a 

 wound parasite, its development is facilitated by the 

 presence of dead wood on which it grows and produces 

 its perfect stage. Dead stubs which are left are the 

 result of poor pruning and topping, and the dead wood 

 about old wounds is exceptionally favourable for its 

 development. The diseased parts should be pruned out 

 and burned, and the wounds should be painted with tar, 

 white lead, or other antiseptic substance. 



1 Fetch attributed the early stages of this disease to Gloeosporium 

 alborubmm, and the later stages to Botryodiplodia elasticae, which he believed 

 to be identical with the fungus causing the dieback of the cacao. 







