RUBBER (HEVEA) DISEASES 25 
In no sense do these small mushrooms derive their nourishment 
from the rubber plant. They are epiphytic and may be disregarded 
in plantation work on a large scale. 
WHITE THREAD-BLIGHT 
The stems and leaves of young rubber trees in dense parts of the 
jungle were occasionally found overrun with a mycelium (Marasmius 
sp.) in the form of white coarse-branching strands. The branches of 
a young tree about 4 feet high were observed in one instance to be 
completely overlaced with these strands. The strands extended to 
the twigs and spread out fanwise over the under side of the leaves, 
matting them together and causing them to turn brown, fall from 
the twigs, and remain suspended by the mycelial threads. The 
mycelium was entirely aerial, and in no case either on Hevea or 
on other jungle plants was it observed to take its origin from the 
ground. Developing on the branches first, the mycelium spreads to 
the leaves. • The strands, composed of thick-walled hyphse, branch at 
varying angles and are of a more or less uniform diameter on the 
woody parts of the plant. On the under side of the leaves the 
strands become more finely divided and cover the entire surface 
with a thin cobweblike layer, which later becomes mealy. The layer 
in this stage does not readily separate from the leaf. That part of 
the leaf covered with the mycelium soon loses its green color, turns 
brown, and checks transversely. If the entire surface is affected 
the leaf falls and may start new infections if it lodges in the foliage. 
The fructifications of the fungus were not observed. On fallen leaves 
of Inga affected apparently with the same fungus, fruiting struc- 
tures of a species of Marasmius were observed, but they were too 
immature for determination. There was no invasion of the tissues of 
the host. The mycelium could be pulled from the epidermis; hence 
the fungus is apparent^ epiphytic. The damage results from a 
smothering of the twigs and leaves. 
Petch has described two forms of white thread-blight on tea in 
the Orient. One is said to be parasitic, the organism not yet having 
been determined; the other is epiphytic and is referred to Maras- 
mius pulcher. It would appear that both forms are known to 
occur on Hevea. 
The damage from white thread-blight is not likely to be of con- 
sequence. Only in crowded seedlings would the blight be expected 
to appear, and the condition favoring its growth can be easily 
corrected. 
Five different forms of these hairlike mycelia were observed. 
Three were of the polished smooth-cylindrical type and exhibited 
considerable tensile strength when pulled from the plants. The 
most common was dense black in color. A wine or claret colored 
form was next in abundance. A yellowish brown form was rarely 
observed. The fourth type was not smooth and polished but mi- 
nutely pubescent and of considerably less strength than the others. 
A fifth form was flat and usually closely appressed to the sub- 
stratum. 
All of these hairlike nwcelia represent the vegetative part of 
species of Marasmius. The dead-black shining cylindrical form 
produced fructifications referable to M. eauicrinis. 'The fructifica- 
