16 BULLETIN 1380 U. S. DEPARTMENT OF AGRICULTURE 
disease, but the fructifications of the fungus were not found. Be- 
tween the bark and the wood broad flat reddish black bands or rhizo- 
morphs were present. These were pressed to the surface of the wood 
and in some places had been followed by borers. The outer layers 
of the wood were of a blue color, but there was an absence of the 
foul smell attributed to the disease in the East. There was no evi- 
dence that the root was infected by Ustulina or by Poria vincta, 
which produces red-colored strands. 
On the other hand, a closely related fungus was common on Hevea 
and was found to cause infections in old priming wounds and tap- 
ping cuts. This fungus is Stilbuni cinnabarinwii, as its conidial 
stage is called. The perithecial stage Megalonectria pseudotrichia 
was more common. Around the edges of the wounds the conspicu- 
ous small smooth red stalks with apical pink or red conical apothecia 
were produced in great numbers. The apothecia were especially 
abundant on the bark of Hevea which had been scorched by fire. The 
fungus was also present on the tops of living Hevea stumps, affecting 
the formation of the callus at the edges. 
Sphaerostilbe repens may be distinguished by the fact that the 
conidial and perithecial stalks are hairy, at least for a part of their 
length. The fungus apparently is not an active parasite and is liable 
to follow adverse conditions of growth. Van Overeem considers it 
mostly saprophytic, especially on swampy, low, wet land. In this 
class would also fall Stilbella heveae, described by Zimmerman on 
dead branches of Hevea in the Orient. 
OTHER ROOT FUNGI 
During the present investigation a large number of fungi have 
been collected from the roots of various jungle trees felled in clear- 
ing operations and on decaying roots of cacao, caju, and other of 
the more permanent crops frequently associated with Hevea in small 
plantations. The repeated occurrence of a number of these fungi on 
decaying roots both of Hevea and associated crops intermingled in 
a rich wet humus soil and also on the drier sites introduces a patho- 
logic condition which is to be expected under the circumstances. 
Only those which appear to be potential pathogens will be discussed. 
In this group will also be included the fungi which act upon the 
dead tissues of the living trunk. The destruction of the dead though 
mechanically important wood of the tree leads eventually to a 
reduction of vigor and to windfall. 
TRAMETEX CORRUGATA 
One of the most common wood-destroying fungi in the Amazon 
Valley is Trametes cormgata (Pers.) Bres. It attacks the wood 
apparently of all forest trees. It is also a wound fungus on Hevea. 
It causes a butt rot, entering the tree through various injuries to 
which its base may be subject. The decayed wood may be entirely 
broken down or tunneled out by white ants, causing the tree to be 
hollow at the base (PI. X, A). 
The fructifications are easily recognized by the reddish brown 
upper surface and white margin (PI. X, B). It is frequently thin 
and flexible. The pores on the under side are yellowish white and 
irregular in shape. Internally the fungus is white. 
