38 BULLETIN 1380, IT. S. DEPARTMENT OF AGRICULTURE 
first appear on the surface of the pods. These soon become black 
specked with pycnidia and may be elevated a millimeter or more 
above the surface of the pod. Later, the surface of the elevations 
becomes roughened. With the development of perithecia cracks 
appear, and finally the entire canker breaks up through the inva- 
sion of secondary fungi. Chief among the latter are Diplodia 
theobromae and Gloeosporium alborubrum. The entire thickness 
of the outer pod tissues is involved. When one or more of these 
cankers develop on a pod it soon dries up. remains suspended for a 
time on the tree, and then may either fall from its stem, which re- 
mains attached to the tree, or the stem may fall with the pod. The 
immature seeds are rapidly attacked by Diplodia, and their contents 
soon become black and shrunken. A count of the pods on some trees 
near Para showed an infection of more than 60 per cent. 
CONTROL 
The methods that have been proposed for the control of the 
disease have not been carried out to the extent that would be neces- 
sary for definite conclusions. Since individuals in a large plantation 
may not be treated with profit, a more comprehensive control should 
be evolved. 
PROTECTION 
To afford protection by giving attention to the normal environ- 
ment certain measures would be considered. To interfere with dis- 
seminating agents would probably involve a consideration of pre- 
vailing winds. It is not known to what extent insects and other 
animal life distribute the spores of the fungus. Local animal life 
is probably a factor. Spores have been detected on the bodies of 
ants, slugs, and bees. In establishing new estates in regions far 
removed from infected plantations or extensive stands of wild trees 
a knowledge of the prevailing direction of winds would no doubt 
be of service. The selection of the site with regard to altitude and 
also intervening elevations giving direction to air currents would 
be considered. Since the rapid propagation of the fungus is pro- 
moted by rain, fog, and dew. the selection of the higher sites where 
the wind would be a factor in dispelling the moisture on the leaves 
should be considered. Heavy dews during the dry season would no 
doubt prove as effective in promoting the development of the 
fungus on young closely adhering leaves as rain during the wet 
season. Rapid evaporation caused by wind on exposed sites would 
tend to reduce the severity of infection. Stahel has pointed out that 
the spread and destructiveness of the fungus are largely dependent 
on climatic factors. He found that trees on exposed places in the full 
sweep of the wind were less severely infected. Consideration of soil 
reactions with regard to fertility is of importance in that the more 
vigorous the tree is the less liable it is to be rapidly weakened by 
repeated defoliations and hence to attack by secondary parasites. 
It has been observed that the effect of the fungus on trees growing 
on soils of low fertility is more serious, OAving to the rapidly weak- 
ened branches being attacked by Diplodia and other fungi. Wet, 
poorly drained soils promote the rapid action of the fungus for the 
same reason, viz, that the trees are usually less vigorous through 
