RUBBER (HEVEA) DISEASES 23 
sist of alternating loose and densely woven hyphse. with a smooth, 
hard outer crust. 
Several species of Septobasidium are found on the stems and 
branches of Hevea. but the specimens collected in most cases were 
sterile or immature and could not be determined. 
One species commonly occurred at the base of young seedlings and 
extended below the surface of the ground. Its structure distin- 
guished it from certain Hypochnus and hyphomycetous forms of 
similar habit. 
Another species was characterized by the formation of a five to 
six storied structure, each continuous layer separated by branched 
septate filaments. Each layer is plainly distinguishable to the un- 
aided eye. This fungus frequently covered the stems of young trees 
for a distance of a foot or more. When the outer slaty gray to 
sooty black layer flakes off in patches the stem presents an un- 
sightly appearance. 
A species found once forming a small patch on a Hevea branch 
was distinguished by its sooty gray or mouse-colored felty structure 
of loosely woven hyphse without the usual pillared layer and its 
velvety surface. The species may be referred to Septobasidium 
fumigatum. 
The fructification of a species was collected by C. D. La Rue on 
Hevea at Cobija. Bolivia, which differs from the spongy velvet 
forms above mentioned. It resembles the thallus of an incrusting 
lichen. It is dry. hard, and leathery, honey-yellow in color, and is 
divided into many narrow reticulate segments at the margin. The 
dense outer or fruiting surface is separated from the compact basal 
layer by only a slightly less dense middle layer. This species is 
referable to Septobasidium frustulosum. 
The species of Septobasidium ordinarily are epiphytic on the 
living bark. It has recently been determined that some species at 
least are associated with colonies of scale insects which are killed 
by the fungus after the manner of the entomogenous fungi to be 
later described. In India and Ceylon certain species after destroy- 
ing the insects penetrate the cortex of the tea bush and kill the 
plant. Other j^arasitic species are reported from Japan on acacia, 
mulberry, and tea. Septobasidium frustulosum causes a serious dis- 
ease on stems and branches of ash in Mexico. 
With the exception of the species found at the base of seedlings 
which appeared to cause a slight swelling the various forms ob- 
served in the Amazon Valley on Hevea were epiphytic. Xo evi- 
dence of penetration was noted. If any ill effect results it is due 
to suffocation of the parts overgrown by the fungus. 
CLARET-COLORED CANKER 
The disease known as claret-colored canker, referred both to 
Phytophthora and Phythium and reported to be destructive to Hevea 
in the East, was not found in the Amazon Valley during the present 
investigation. Several small cankers originating in tapping cuts and 
on untapped trees which could not be referred to the diseases else- 
where described were examined. Although some of the character- 
associated with claret-colored canker were present, those by which 
the disease is best known were absent. 
