515 



AGRICULTURAL BULLETIN 



OF THE 



STRAITS 



AND 



FEDERATED MALAY STATES. 



No. 11.] NOVEMBER, 1908. [Vol. VII. 



A ROOT DISEASE OF PARA (HEVEA BRAZILI- 

 ENSIS) RUBBER TREES. 



By W. J. Gallagher, m.a. Government Mycologist, f. m. s. 



A fungus, which attacks the roots of Para Rubber trees with fatal 

 results, appears from the number of communications received by the 

 Department of Agriculture to be fairly common at present over this 

 Peninsula. It is doubtful if there is an estate free from it, as its 

 presence, even when it has killed trees, often remains unsuspected. 



The disease is seldom distributed over an entire estate, but is 

 confined to limited areas in which at first a tree here and there is 

 attacked. Half a dozen or more vacancies may often be seen together 

 when, owing to a misconception of the cause of death or for other 

 reasons, no preventive measures were taken on the death of the first 

 tree. The trees succumbed one after another as the disease spread. 

 The "supplies" were failures too ; planted in a soil full of threads of 

 the fungus they were soon attacked by it and either never "struck" 

 or died shortly after doing so. On these infected areas the mortality 

 is often as high as thirty trees per acre, but for a whole estate the 

 yearly average is probably not a tree per acre. I have seen only one 

 particularly bad instance ; in 400 acres of trees two and a half years 

 old, about five per cent had died, and two dead trees were never 

 adjacent. The incidence is heaviest on peaty soils, and where there 

 has been a bad burn. 



The disease occurs among trees of from fifteen to thirty months 

 old. I have not noticed it on trees older than two and a half years. 

 Nursery plants of a few months old may be attacked, and will quickly 

 succumb if a source of infection is at hand. 



Symptoms. , 



The disease is not discovered, as a rule, until the tree is dead. 

 The first symptoms are somewhat as follows: — The leaves of a healthy- 

 looking tree suddenly become brown, first round the edge and especi- 

 ally at the tips, and the entire leaf soon loses its natural colour : this is 



