DISEASES OF HEVEA IN CEYLON. 



By T. FETCH, B.A., B.Sc. 

 Government Botanist and Mycologist, Ceylon. 



WHEN it is realized that more than thirty years have 

 elapsed since Hevea brasiliensis first began to be planted 

 on estates in Ceylon, it will be evident that our premier 

 rubber tree has now successfully withstood a fairly 

 prolonged exposure to the parasitic fungi of its new 

 habitat. During that period it has acquired compara- 

 tively few diseases, and the majority of those have not 

 proved serious. The total number of recorded diseases 

 of Hevea has remained stationary for the last six years. 



It is not the intention of the present paper to give a 

 summary of the known diseases of Hevea. That has 

 previously been done on several occasions, and, in the 

 case of most of the diseases there is nothing to add to 

 what has already been published. The following account 

 will be confined to those diseases which are of practical 

 importance in Ceylon at the present time a limitation 

 which excludes all leaf diseases and practically all root 

 diseases, with the possible exception of brown root 

 disease. 



While Fomes lignosus (the Fomes semitostus of pre- 

 vious Hevea literature) occurs chiefly in association with 

 jungle stumps in young clearings, brown root disease 

 may appear at any stage and, apparently, independently 

 of any dead wood. It is, however, much less destructive 

 than F. lignosus, and as a rule is confined in each case 

 to a single tree. But, judged by the number of cases, 

 it is now the commonest root disease in Ceylon. 



Roots attacked by brown root disease are characterized 

 by an encrusting mass of earth, sand, and small stones 

 bound together by fine brown mycelium. In most cases 

 the outer layers of mycelium ultimately turn black, so 



