RUBBER (HEVEA) DISEASES 51 
swarm spores are liberated through a longitudinal split in the 
sporangium and are washed by dew or rain over the surface of 
leaves and young stems and enter the host through the stomatal 
openings. Here by division of their cells a new thallus is produced. 
The influence of the parasite may extend considerably beyond the 
zone of actual infection, causing the formation of deposits in the 
cells of the mesophyll. The deposits, at first reddish, are black when 
old. The algal cells in the tissues are green in early stages of in- 
fection but are reddish when older and give the general red color to 
the spots. A layer of algal cells may develop between the epidermis 
and the mesophyll, causing the latter to crack and blacken. 
The parasite was found on both healthy plants and those weakened 
by various causes. The injury results in the destruction of the leaves 
and shrinkage of the stems. 
FRUIT AND FLOWER DISEASES 
PHYTOPHTHORA POD-ROT 
A Phytophthora disease (PhytopMhora faberi Maubl.) of the 
pods of rubber was found near Utinga at Para during the heavy rains 
in November. It was characterized by a sodden greenish watery 
discoloration of the outer fleshy wall at the base of the stem. From 
this point it extends along the line of sutures between the lobes of 
the pod to the distal end. Here the three zones of infection meet 
and spread to the sides, the entire green outer fleshy wall of the pod 
becoming soft and rotten, so that the epidermis can be slipped off 
with the thumb. The decay rarely begins at the distal end or on the 
sides of the pods. The discolored zones between the lobes of the 
pods soon develop a whitish or grayish film, which extends over the 
entire pod as the rot advances (PI. XVII. C). Before the pod be- 
gins to shrivel the fleshy wall cracks open along the grooves, begin- 
ning at the stem. The woody wall beneath does not open until some 
time after the outer wall becomes dry and shriveled. The seeds, 
which are immature when infection occurs, are hollow and decayed. 
The dry shriveled pods may either fall from their stems by the 
subsequent spreading of the woody wall or they may remain at- 
tached to the tree indefinitely. Old dried pods from infections of 
previous seasons were frequently found attached to the trees. There 
was no evidence that the disease extended to the twigs or young 
shoots. The fungus is very destructive to cacao pods in the Ama- 
zon region and is no doubt the most common source of the inoculum 
on Hevea. In some of the cacao plantations visited as high as 50 
per cent of the pods were destroyed while still young. 
If the white surface mycelium on the pods is examined it is found 
to consist of nonseptate hyphse of varying diameters. In the larger 
intercellular spaces the hyphse are fusiform or pouchlike, becoming 
reduced in the narrower spaces or where they penetrate the cells. 
The hyphse later rupture the epidermis, emerge, and form on the 
surface a network of delicate unbranched sporophores. On the ends 
of the sporophores small hyaline egg-shaped sporangia are produced 
with papillate openings at the apex. The sporophores continue to 
develop, pushing aside the original sporangium when another is 
