247 



slowly and only in contact with roots ; isolation is, therefore, un- 

 necessary, and so also is liming, providing that the diseased roots 

 are removed and the wood from the affected area taken up and the 

 area dug over. An examination of the laterals of trees which are 

 adjacent to the dead tree should be carried out, and such as are 

 diseased should be amputated to a point where they are healthy. 



Stem Diseases. — Thridaria tarda, Bancroft, of which the Diplodia 

 stage causes the "die-back" disease, has been investigated and the 

 life-history completed. The fungus, which is common as a saprophyte 

 on dead material, can infect the plant at wounds. Investigations have 

 shown that the fungus can be transferred from cacao to Hevea and that 

 the Diplodia condition of the fungi on cacao and Hevea are indentical. 

 This, coupled with the work of other authors, shows that the fungus 

 is widely distributed through the cacao and rubber-producing countries 

 of the Tropics. The fact that the fungus only infects at a wound 

 which involves the exposure of the wood, and, therefore, not a good 

 tapping surface, coupled with the fact that its effect on the plant 

 depends largely on the condition of health of the plant, classes it as an 

 ordinary wound parasite. 



The disease has been reported from all the Federated States of 

 the Peninsula. There is, however, a great tendency to attribute far 

 more effects to the fungus than are in reality initiated by it, and the 

 reckless removal of branches, which are shedding their leaves from 

 some physiological cause, must be guarded against. 



The work, which furnishes an account of the life-history of the 

 fungus, the spread of the disease and its method of treatment, will be 

 published shortly in Bulletin IX of the Department of Agriculture. 



Corticium javanicum, Zimmermann, the "pink" fungus has been 

 reported from two districts, where it was, however, present in small 

 amount. It is a well-known parasite of Hevea, tea and other plants 

 in India and in Ceylon. The disease originates most usually at the 

 fork, where the fungus produces a pink patch which extends to the 

 sides of the trunk below and to the branches above the fork. It is 

 easily identified by means of the colour. The removal of the fungus 

 with adhering bark when it is young and the sealing of the wound has 

 been recommended. Such branches as are ringed by the fungus must 

 be amputated, and when young trees are affected they must be cut off 

 below the affected part. These are direct methods of treatment. In 

 places where the disease occurs repeatedl}^ it is proposed to spray in 

 the fork with Bordeaux mixture as a preventative ; a Vermorel's 

 cascade sprayer is being obtained for the Department and arrange- 

 ments are being made to have these sprayers stocked in this country. 

 There has been up to the present, however, no necessity to put such a 

 method of treatment into force. 



The " thread blight " fungus has been reported on one estate. 

 The fungus has not yet been indentified owing to the absence of spore- 

 bearing organs ; to judge from analogy, 'however, it may be expected 



