F. T. Brooks 221 



The only mode of treatment is to cu1 ouf and bum all affected 

 parts as soon as the disease is seen. Prompt action is particularly 

 necessary in dealing with this disease on account of the rapidity with 

 which it develops. If an estate is being thinned out, the rubber trees 

 which are discarded should not be allowed to remain Lying in the planta- 

 tion indefinitely as such material offers a good breeding-ground for this 

 fungus. 



Many different names have been given to this fungus but Botryo- 

 diplodia theobromae has the right of priority as far as its common conidial 

 stage is concerned. In 1911 Bancroft (l) described the development 

 of an ascus stage in its life-history. During my residence in Malaya 

 I devoted special attention to trying to find the perithecia described 

 by Bancroft but without success. Branches of Hevea attacked by 

 Botryodiplodia were kept under conditions favourable for the formation 

 of perithecia but in no case did ascus formation result. As far as I 

 am aware no other observer has found the Thyridaria which Bancroft 

 considers is the complete stage of the Botryodiplodia, and until confirma- 

 tion of the presence of a perithecial stage is obtained it seems preferable 

 to retain the name Botryodiplodia theobromae for the fungus. 



8. Bark Diseases. 



Diseased bark was frequently seen in rubber trees, but apart from 

 a careful search in vain for the bark canker of Ceylon attributed 

 by Petch (io) to Phytophthora Faberi I had no time to investigate 

 troubles of this nature in detail. As soon as the bark of a rubber 

 tree becomes diseased, boring beetles are almost certain to attack 

 the affected tissues. Where boring beetles attack a tree high up 

 there is obviously no connection between their invasion and the action 

 of a root parasite as described above under Ustulina zonata and 

 Sphaerostilbe repens. I have occasionally seen borers penetrating the 

 laticiferous layer of healthy bark by continued attacks, but usually 

 they can only successfully invade bark which is diseased. 



None of the diseased bark examined in Malaya presented the features 

 associated by Petch (10) with the bark disease caused by Phytophthora 

 Faberi in Ceylon. Many attempts were made by culture experiments 

 to isolate a Phytophthora from bark taken from the junction of healthy 

 and diseased tissues but in place of it some species of Fusarium or other 

 hyphomycete was invariably obtained. This, however, is not sufficient 

 evidence to justify the belief that species of Fusarium are capable of 



