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land. The jungle trees are felled, leaving the stumps 
in the ground, and the luxuriant undergrowth is cut 
down. After a period of dry weather the timber 
and dried undergrowth over the felled area are fired. 
After the fire, the stumps and large logs, though 
much charred, still remain and during decay form 
suitable food material for fungi. The original source 
of the root diseases of Hevea brasiliensis can be 
traced to the jungle stumps and logs left on and in 
the ground. If the land were cleared thoroughly 
before planting it could be stated definitely that root 
diseases would be negligible on Malayan rubber 
plantations. 
The following roof diseases have been investigated 
in Malaya: — 
Fomes lignosus (semitostus ) . 
This fungus causes most damage on young 
plantations with trees under seven years of age. 
Occasionally in localised areas it has caused 
considerable devastation. Most plantations have 
suffered loss from this disease; but since, owing 
to close planting, the trees have to be thinned out 
at the age of six or seven years, the loss caused 
by this disease has not, in the past, had serious 
consequences. 
The distinguishing characteristic of this fungus 
is the white external rhizomorphic strands running 
over the lateral roots of the tree. The fruit-bodies 
are remarkable in being persistently sterile, while 
similar fruit-bodies of closely allied species produce 
millions of spores, each capable of infecting a 
healthy tree under suitable conditions. 
Sphaerostilbe repens. 
This fungus causes a root disease of rubber trees, 
of any age, growing in acid, water-logged soil, and 
