6O2 RUBBER 



debris when thinning out. It should, however, be stated 

 that, though the disease is extremely rapid in its action 

 when it does occur, it has not proved so dangerous as 

 was at first anticipated. The idea that an exudation of 

 latex from the upper parts of the stem is a symptom of 

 this disease has been discarded. 



Bancroft has discovered, on material attacked by 

 Botryodlplodia theobromse, an ascigerous fungus, Thy- 

 ridaria tarda, which he considers is the higher stage 

 of the former. The disease is, therefore, frequently 

 referred to under the latter name. 



The most serious disease of Hevea known at the 

 present time is canker, not only because it may kill the 

 tree, but because, even when the attack is slight and the 

 tree recovers, the result of the treatment may be such 

 that the tree cannot be tapped again for several years. 

 As in the case of cocoa, the term " canker " which has 

 been applied to this disease is misleading, since in most 

 cases no canker, i.e., no open wound, is produced. If the 

 tree is killed outright the bark remains quite smooth and 

 unbroken. 



This disease was first recorded in Ceylon in 1903. Since 

 then it has been found in South India, Burma, and Java. 

 As it is identical with cocoa canker, it will no doubt 

 ultimately be found to occur in all cocoa-growing coun- 

 tries. According to the present records it has not been 

 detected in Malaya, but several of the accounts of Hevea 

 disease in that country suggest that it occurs there, but 

 has not been recognized as such. 



The fungus which causes the disease (Phytophthora 

 Faberi, Maubl.) has been found to attack every part of 

 the tree except the leaves. It is responsible fo<r the rot 

 of the pods, when, in a wet season, the fruits turn black 

 and do not dehisce, but remain for a long time attached 

 to the branches. From the fruits it often passes to the 

 green shoots and kills them back, or it attacks the leaf- 

 stalks and causes extensive defoliation. The attack on 

 the leaf-stalk is usually indicated by the appearance of a 

 dark brown or blackish ring on the stalk, after which 

 the leaf disarticulates. An outbreak of pod disease is 

 frequently followed by general recrudescence of stem 



