AGRICULTURAL BULLETIN 



OF THE 



STRAIT5 



AND 



FEDERATED riALAY STATES. 



No. 7.] JULY 1911. [Vol. X 



A NOTE ON THE CANKER OF HEVEA 

 BRASILIENSIS. 



By Keith Bancroft, B.A. 



Assistant Mycologist, Department of Agriculture, F.M.S. 



The "canker" of Para rubber was first investigated by Carriithers 

 in Ceylon in 1903-04. Like the "canker" of cacao it owes its name 

 rather to the fungus (Nectria sp.) to which it was first attributed, than 

 to the effects produced by the disease. On Hevea plantations in- 

 Ceylon there has not been much damage caused by "canker", but in 

 mixed cacao and Hevea cultivations the disease is regarded as being 

 more serious. Hitherto there has been no record of its occurrence in 

 this country. 



The symptoms are the following:— 



External symptoms at first are obscure ; on young trees the bark 

 rnay appear to be a little darker in colour, but on older trees there 

 are no observable external symptoms at the commencement. The 

 first symptom which is usually recorded is the cessation of the flow 

 of latex; when this occurs, if the outer bark be scraped away, a black 

 layer is found under which the latex layer is obviously discoloured. 

 When recently diseased the inner tissues possess a grey or neutral 

 tint with a well-defined black border, but in advanced cases of disease 

 they become of a claret or purple colour. In some cases a purplish 

 red liquid is exuded from the diseased parts' These are briefly the 

 symptoms described by Fetch in the Circulars and Agricultural 

 Journal, Royal Botanic Gardens, Ceylon, Vol. V, No. 13, igro. 



