RUBBER (HEVEA) DISEASES 13 
the submerged roots it is wet and plastic. It may extend to a 
considerable depth in the roots and upward in the trunk for a 
distance of a foot or more above the root collar. The affected 
roots may appear more brown than in the normal state. When the 
entire root is decayed the bark may be readily removed, showing 
a whitish mycelial development on the under surface. After the 
brace roots are decayed the tree may be blown over. Two trees 
in a leaning condition were affected by this fungus. 
The fungus usually fruits at the surface of the ground in the 
root crotches or on roots that are exposed. In one case the sporo- 
phores were produced on the trunk some distance above the root 
collar. The entire side of the trunk was decayed for a distance of 
2 feet above the ground. 
The sporophores are generally irregular brackets, sometimes with 
a false lateral stem (PL VI ). The upper surface is brown incrusted. 
smooth, and concentrically zoned. The margin is white when in a 
growing condition. The pores are white when fresh and do not 
change in drying. The context of pileus is whitish next the crust 
and light brown below. 
This fungus is in no sense parasitic but enters the tree through 
wounds. It is not expected to attack young trees, but will be found 
on trees that have attained considerable age and size or trees that 
have developed considerable heartwood in the roots and trunk. Al- 
though apparently more intimately associated with Hevea, the fun- 
gus undoubtedly will be more abundantly found on jungle trees 
when the subject is studied in more detail. 
BLACK LIXE-ROT 
The black line-rot fungus {Ustulina zoootn (Lev.) Sacc). the 
cause of a serious root and stem decay in the Orient, was found asso- 
ciated with cankers in the root crotches of Hevea at three different 
stations. Since the presence of no other fungus could be demon- 
strated in relation to the cankers it is believed that they were caused 
by this Ustulina. The cankers had apparently originated on the 
sides of the lateral roots and had spread to the base of the tree, 
affecting a strip on the main trunk about a foot above the root col- 
lar. The area affected was in each case still partially covered by the 
dead bark, but the wood was rotted, checked, and shrunken so that 
it could be easily picked out with a knife, leaving a cavity. The 
solid but dead wood immediately surrounding the cavity was in- 
vaded transversely and vertically with broad conspicuous zigzag 
black lines. (PL VII. A.) Sometimes these lines when cut ap- 
peared as circles or parallelograms and inclosed an area of brown 
wood. This zone joined with the living wood of the tree. The 
bark to the right and left produced latex when cut. but the living 
bark above the canker appeared dry and produced no latex. The 
bark covering the zone of bladv line- bore the fructifications of the 
fungus in various stages of development. On the root at the sur- 
face of the ground small black nodules were present. These were 
sterile and were evidently imperfectly developed fruiting bodies. 
The normal fructifications were congregated at the root collar. 
They consisted of broad flat plates with irregular surfaces and were 
loosely attached to the bark (PL VIII, A). The young fructirica- 
