2 BULLETIN 1380, U. S. DEPABTMENT OF AGBICULTUBE 
fectly known. The range of hosts of many of the wood-destroying 
species often varies widely from that of the same species in the 
eastern Tropics. A few apparently have an American distribution 
only. A few of pathogenic importance have been found to be new 
to science. The appearance of new and interesting phases in the 
life history of old and well-known species is not uncommon. Owing 
to the presence in the Amazon Valley of practically all the usual 
tropical crops which have received little or no care after planting, 
the region is of great interest to students of plant diseases. In fact, 
the field is new, and with the exception of a few collections made by 
early botanists, very little mycological and no constructive patho- 
logical work has been done. 
Many of the problems with which the rubber grower is concerned 
are in intimate relation to the fungous agents of disease. In the 
South American region this is especially true. Before measures for 
the control of fungous diseases or for the practical consideration of 
the problems arising therefrom in plantation work in which forest 
fungi arc concerned can be introduced, it is necessary to have funda- 
mental knowledge of the life histories of the causal organisms. To 
supply a part of this information with the view of becoming more 
familiar with the diseases concerned in the growing of rubber in the 
American Tropics is the aim of this bulletin. 
The system of classification followed in the main is that of the in- 
vestigators best informed on the subject. In the Tropics very few 
common names of fungi have been proposed; consequently the Latin 
names of the species are strictly adhered to. In cases where the 
effects of the fungus or the conditions producing the disease are 
highly characteristic, a common name for the disease is also em- 
ployed. The number of species of fungi recorded on Hevea in the 
Amazon Valley seems unusually large. It is small, however, in 
comparison with the number associated with some of the economic 
crops of the world. The work has been conducted on the basis of 
giving as complete a survey of the fungi and diseases of Hevea as 
time would permit. A list of all the fungi known to occur on Hevea 
in any part of the world is included. Fungi are widely distributed, 
and the species shown in this study may be found throughout the 
tropical belt. 
In the Tropics, where plant pathology is in its beginning, it seems 
desirable to record all fungi on a given host, for the reason that 
under the conditions of clearing away the native forest, fungi which 
now seem unimportant may later cause disease on the introduced 
crop. This has been largely true in the case of Hevea. Aside from 
the more practical consideration given to each fungus, some details 
with regard to the chief characteristics of the different species and 
the classes, orders, families, and genera to which they belong are pre- 
sented. It is hoped that this will give the bulletin a wider useful- 
ness from a taxonomic standpoint and w T ill also explain many of the 
terms necessarily used in a w T ork of this kind. 
GENERAL PATHOLOGICAL CONDITIONS AND SANITATION 
Not until the past few years have the diseases of tropical crops in 
America received much attention. Now 7 that it is realized that 
serious economic loss will result unless some effort is made to combat 
