LEAF DISEASE OF PARA RUBBER 5 
Reporting the following year (3) upon a visit to rubber planta- 
tions in Dutch Guiana, Bancroft viewed the situation as a whole 
still more seriously and predicted the eventual abandonment of rub- 
ber culture in these countries. In Dutch Guiana, he stated, " on the 
majority of estates the trees are badly affected and are dying in 
large numbers, some estates having already lost in certain areas 
one-third of the total number of trees." 
In 1917 Rorer (19) reported the disease widespread in Trinidad 
and from its general distribution concluded it must have been present 
for a number of years. Although in some places both old and young 
trees had been actually killed by the repeated defoliations, he did not 
consider it in general so virulent as in the Guianas, " probably on 
account of less favorable climatic conditions for fungus growth." 
From the foregoing review it is seen that what was first considered 
a disease of secondary importance after a few years has spread in 
the plantations and practically ruined the local rubber industry. 
Since the South American leaf disease has been found on three 
different species of Hevea (H, brasiliensis, H. confusa, and H. 
guyanensis) and is known to occur in such widely separated regions 
as the upper and lower Amazon valleys, the Guianas, and Trinidad, 
its distribution is probably coincident with that of the native Hevea 
species. It has never been reported to attack any other plant than 
Hevea, and such attack is unlikely, since the fungus seems to be an 
obligate parasite. On the accompanying map (fig. 1) of equatorial 
America, there are indicated the approximate limits of natural 
distribution of the genus Hevea, adapted from an earlier chart by 
Ule (26), and the localities and regions where the leaf disease has 
been reported on either wild or cultivated trees. 
From the researches of Stahel the disease found in these remote 
regions is evidently caused by the same fungus, which was hitherto 
known by at least five different names. In 1915 Stahel gave it the 
now generally accepted regional name, " South American leaf dis- 
ease," which was rather unfortunate in view of its subsequent dis- 
covery in Trinidad and the possibility that further search may dis- 
close its presence in other parts of the western Tropics. 
The presence of the disease in Trinidad, which is supposed to lie 
outside of the natural range of the host genus, is difficult to explain. 
As in most of the other western countries, the plantations there have 
come mainly from seed imported from Ceylon or Singapore. There 
were, however, one or two importations direct from South America , 
e. g., the " Rio Negro " trees at St. Augustine Experiment Station ; 
so that the disease may possibly have been introduced in this way. 
Outside of South America and the island of Trinidad, its further 
geographic distribution is unknown. Scattered plantings of Hevea 
rubber in Mexico, Nicaragua, Costa Rica, Panama, and Haiti re- 
cently inspected by members of a rubber expedition from the United 
States Departments of Agriculture and Commerce were reported to 
be healthy. Its occurrence in the great plantation areas of the Far 
East is unlikely, since the fungus is apparently not very well adapted 
to withstand prolonged inactivity. Nothing even remotely suggest- 
ing the characteristic symptoms of this disease was observed by the 
writer while inspecting a large number of rubber estates on the 
islands of Java and Sumatra during the years 1919 to 1921. This is 
