152 F. T. Brooks. 
A DISEASE OF PLANTATION RUBBER CAUSED BY 
USTULINA ZONATA. 
By F. T. Brooks, M.A., 
Senior Demonstrator of Botany, Cambridge University ; 
formerly Government Mycologist, Federated Malay States. 
[With Six Figures in the Text]. 
Introduction. 
S OON after arriving in the Federated Malay States at the 
beginning of 1914 the writer frequently saw a disease of 
rubber trees which had not hitherto been recorded in Malaya, the 
disease affecting primarily the collar and root system of the trees. 
Preliminary investigation shewed that the trouble was probably 
caused by a fungus, as hyphze were abundant along the junction of 
diseased and healthy tissues. The characters of this disease were 
different from those of the root diseases caused by Fomes semitostus 
(now more correctly named Fomes lignosus), Splicerostilbe repens and 
Hymenochcete noxia, but it was not until towards the end of the year 
that 1 found the fructifications of the causative fungus, which proved 
to be Ustulina zonata (Lev.) Sacc. This fungus is the cause of a 
common root disease of tea in Ceylon (4), and although Petch (5) 
wrote in 1911 that “ it is not yet certain that Ustulina causes root 
disease in Hevea," he pointed out in 1914 (6) that several cases of 
Ustulina on rubber had been reported in Ceylon in fields where 
Hevea had been planted among tea which had subsequently been 
allowed to die out. This is the only reference to the occurrence of 
Ustulina zonata on rubber I have been able to find in published 
accounts of the diseases of Hevea brasiliensis, and no general account 
of the manner in which it attacks this host has hitherto appeared. 
The disease has not yet been recorded on Hevea in Java, Sumatra, 
o^ Borneo. 
Field Observations. 
The part of the rubber tree chiefly affected by this disease is 
the collar, which is usually attacked first on one side only. In this 
region the bark dies and the wood below becomes brown. As the 
dead tissues break away a shallow depression is often formed on 
one side of the trunk at soil level. Neighbouring lateral roots and 
the portion of the tap root immediately below the collar are often 
affected in the same manner, and in advanced cases the disease 
spreads up the trunk to the height of two or three feet. If the 
