18 BULLETIN 1380, U. S. DEPARTMENT OF AGRICULTURE 
As is well known, some of the most serious root diseases of Hevea 
arise from the spreading of a fungus from decaying stumps of as- 
sociated crops or jungle stumps. The disease spreads chiefly through 
the soil by means of vegetative mycelia following along decaying 
roots and other plant materials. In the case of several of the 
Kosellinia species no adaptation to a particular host has been ob- 
served. They seem to be able to attack and kill the roots of most 
of the plants encountered. 
The fungus Rosellirua bun odes (B. and Br.) Sacc. has been re- 
ported as the cause of a stump rot or a black root disease of pepper, 
tea. coffee, and several species of forest trees in India. In Ceylon 
it attacks tea and hibiscus. In Porto Rico it occurs on coffee and 
associated plants. It was found by South on limes in Dominica 
and on camphor and CastUloa elastica, the Central American rubber 
tree, in Grenada. Xowell reports this fungus on a large number of 
fruit trees, root crops, and various native shrubs in Dominica and 
St. Vincent. In the Amazon Valley it was found on the roots of 
cacao and Hevea. 
The black root disease of Hevea reported by Van Overeem and 
also by Steinmann in Java is attributed to this species. 
The mycelium of the fungus forms fine black slightly flattened 
strands, forming a network over the surface of the roots and be- 
neath the bark (PI. XI, A). These strands may later extend to the 
parts above the soil, where they spread out, forming purplish black 
velvety patches. The mycelium penetrates the wood along the 
medullary rays and later invades the larger cell elements, tilling 
them completely. In cross section the dark-colored mycelium is 
seen as black dots and radial lines. This appearance in the wood is 
characteristic for the species. 
The conidia are borne on the superficial patches. The perithecia 
follow the production of the conidia and are partly embedded in the 
velvety layer. They are characterized by superficial scalelike warts, 
more or less concentrically arranged. 
The species Rosellinia pepo Pat. was not found on Hevea, but was 
collected on the roots of cacao associated with Hevea in small planta- 
tions around dwellings. Since the species from its known activities 
in the West Indies may be expected to attack any plant introduced 
on recently cleared land it is here briefly described. 
The mycelium of this species is distinctly different from that of 
RoselUnia btmodes. Instead of forming black strands the mycelium 
develops white fan-shaped or stellate patches between the bark and 
the wood. On the surface of the root the mycelium develops a 
dense smoky gray layer, which in later stages becomes black. It ad- 
vances above the surface of the soil and forms an enveloping layer 
around the base of the stem. The growing margin is of a light-gray 
color, but it becomes brown or black on cessation of growth. The 
mycelium penetrates the wood in the same manner as that of 
R. bunodes, but since it is white it is invisible until after long 
exposure. 
The conidial fructifications are developed in great numbers on the 
black mycelial layer above the surface of the soil and are composed 
of several vertical parallel hyphre in the form of a bristlelike stalk. 
These hyphae spread out at the apex, and the spherical 1-celled conidia 
