RUBBER fHEVEA, DISEASE? 45 
is separated from the uninfected parts by a purple zone. The 
under surface is reddish brown (PI. XYIIL B). 
In the other a Lepto.-phaeria is apparently the causal organism. 
The upper side of the diseased surface is whitish gray with a faint 
purple tinge and is bounded by a brownish zone. The epidermis in 
late stages is separable from ti s beneath. The under sur- 
face of the leaf is whitish gray. 
Diplodia theobromae is present on the leaves in both cases. 
Not infrequently leave- of middle age on young trees growing 
along the river banks were affected with a blight similar to that 
with which Ascochyta was associated. The fungus, however, in this 
instance was exclusively Pestdlozzia pahnarum Cooke. The leaves 
begin to die at the tips, and the spot spreads uniformly toward the 
base until about midway it affects only the margin for the remainder 
of the distance. The dead parts of the leaf assume a whitish gray 
appearance above, with small greenish spots scattered over the sur- 
face. The lower surface is a uniform reddish brown. Trie edge- of 
the leaves do not curl, as is the case in rim-blight. 
CLADOSPORIUM WILT 
A greenish black mold is sometimes found on withered leaves of 
young Hevea in damp situations. Cladosporiv/m herbcarv/m is asso- 
ciated with this wilt, and in the absence of other fungi it may be 
the contributory cause of the disease. The mold consists of a super- 
ficial greenish brown mycelium, springing from small cell masses 
beneath the epidermis in the form of erect bundles. The conidia are 
produced terminally or laterally on these erect eonidiophore^. singly 
or in chains. The unicellular conidia are from 1 to -3 septate, de- 
pending upon the age of the part of the eonidiophore from which 
they are produced. The conidia resulting from a division of the 
basal or lateral cells of the eonidiophore are usually 1 septate. 
Those produced terminally are unicellular. The conidia are vari- 
able in shape, globose to elongate, hyaline to brown, depending upon 
age. and they are thickened at the end-. 
The fungus on Hevea is probably not of importance and is indica- 
tive of a weakened condition of the host. 
ASCOCHYTA LEAF-SPOT 
This leaf-spot fungus {Ascochyta sp.) attacks the leaves at the 
time they reach maturity. Blackish green or mouse-gray spot- ap- 
pear promiscuously over the upper surface of the leaves, which may 
later become united, affecting large areas of the surface. The spots 
are reddish brown below. They become gray in the centers and, 
being surrounded by the greenish or grayish discoloration, are rather 
conspicuous after the uninfected parts of the leaf turn brown 
(PI. XVII. E). 
In the mesophyll of the leaf the hypha? of the fungus are found, 
and congregate beneath the epidermis to form numerous small 
pyenidia in the gray part- of the -pot-. The pyenidia are small, 
somewhat flattened, and submerged in the When mature 
they open with a small round-beaked ostiole. The -pores are hya- 
