'2'2± Some Diseases of Plantation Rubber in Malaya 



failure of the water supply caused by the presence of the fungus below. 

 On one low-lying part of an estate an outbreak of this .disease was 

 almost epidemic in character, more than 200 trees, one to two years 

 old, growing on peaty soil being affected together. Trees of the same 

 age on higher land with better soil remained unaffected. Poor drainage 

 and a peaty soil often check the growth of rubber trees which appear 

 generally to be more subject to disease under these conditions, possibly 

 on account of a lessened resistance to parasitic organisms. 



Branches affected by this fungus should be cut out and all diseased 

 portions burnt. If an attack on young trees is observed in an early 

 stage the trees which are still healthy should be sprayed at intervals 

 with Bordeaux mixture. 



A Phyllosticta was also sometimes found on the margins of rubber 

 leaves and inoculations showed that it could act as a weak parasite 

 causing a brown discoloration of the leaves from the margin inwards. 

 The spores of this Phyllosticta appeared to be identical with those of 

 Phyllosticta ramicola but it was not possible to carry out comparative 

 cultures to test this. 



12. Gleosporium aXho-rubrum, Fetch. 



Peteh (10) first described this fungus as causing a die-back of the 

 green shoots of Hevea in Ceylon which was often the forerunner of 

 attack of the woody parts by Botryodiplodia iheobromae. The fungus 

 plays the same role in Malaya and what is apparently the same fungus 

 often affects young leaves also. Both upon the young stem ami upon 

 the leaves the pustules of this fungus are pink in colour, the individual 

 spores being hyaline and 14-20/u, x 4/x in size. On young stems of 

 Hevea I have sometimes seen this fungus intimately mixed with Phyllo- 

 sticta ramicola. Where Gleosporium albo-riibrum occurs on recently 

 unfolded rubber leaves it causes them to shrivel from the margin and 

 fall rapidly from the tree. On a few mature trees growing in low-lying 

 land I have seen this fungus so abundant at the time of unfolding of 

 the leaves after '" wintering" that the ground below was thickly carpeted 

 with the leaves which had been shed. Leaves of Hevea brasiliensis 

 at the time of unfolding are of delicate texture and are much less 

 resistant to fungoid attack- than when fully developed. This was the 

 only indication I saw of any present danger of a serious leaf parasite 

 of plantation rubber. 



