RUBBER (HEVEA) DISEASES 27 
SWELLING OF TWIGS 
A fungus (Cryptosporium sp.) was found associated with fusi- 
form swellings at the ends of twigs bearing the inflorescence. The 
relation of this fungus to the swellings has not been determined. 
The bark at first becomes discolored. Later, longitudinal cracks 
appear in the bark, exposing the bast, which becomes hard and dry. 
The inflorescences and leaves of twigs so affected are small and 
poorly developed. 
The fruiting bodies of the fungus may be readily seen with a lens 
as small black circular flattened pustules with central inconspicuous 
papillae. 
INDETERMINATE BRANCH CANKERS 
On several of the small plantations visited the tips of branche 
on some of the trees were dead. In the lower part of the Amazon 
Valley this was usually the result of defoliations by DothideJla uJ>:< 
and its attack upon the stems followed by Diplodia theobromae. In 
some cases the dead twigs showed no signs of infection of an} 7 kind, 
and some appeared in regions where Dothidella was not observed. 
The bark on such twigs appeared shrunken, with longitudinal cracks 
through which latex had at some stage of the disease exuded. Small 
open cankers with the initial stages of callus formations also occurred 
on branches not yet dead. Xo organism was found associated with 
these cankers. They had much the appearance of insect injuries. 
Similar phenomena have been reported from the East and are con- 
sidered a result of the attack of PhytojMhora faberi. 
All small dead branches should be removed and burned. The cut 
should be made sufficiently in advance of the affected parts to pre- 
vent further infection. Since the wounds made in cutting off the 
lesser branches are small and are usually soon healed it may not be 
necessary to treat them. 
Obviously the pruning of small branches can only be practiced 
during the early life of the tree or during the orchard stage. 
The tips of branches may die as a result of the activities of fungi 
in the roots. In such cases pruning them off is of no avail. 
DAMPING-OFF OF SEEDLINGS 
In dense patches of seedlings small suppressed plants here and 
there in the stand, averaging about 6 inches high, were attacked by a 
fungus directly at the root collar. The tissues appeared brown and 
shrunken and were overgrown by a white mycelium. A microscop- 
ical examination in the field disclosed a sclerotic condition of the 
nrycelium resembling that of some of the soil-inhabiting fungi of 
the Rhizoctonia or Sclerotium group. The seedlings were yellowing 
or dead and were held upright by their vigorous uninfected overtop- 
ping neighbors. The general effect appeared to be a result of sec- 
ondary fungous infection following normal suppression. Such a 
disease is not likely to occur in well lighted and aerated places. 
STEM CANKER OF SEEDLINGS 
Seedlings 2 to 3 years old were observed showing disease symp- 
toms on the stems just at the surface of the ground. At this point 
