6 BULLETIN 1380, U. S. DEPARTMENT OF AGRICULTURE 
completely before planting. The reasons for this are obvious. This 
means the removal of large stumps as well as all slash on the area. 
Since there is not likely to be an opportunity to dispose of any 
merchantable timber at a profit, the last recourse is to free the 
area of all jungle material by broadcast burning. Secondary burn- 
ings may be necessary for the destruction of large trunks after sea- 
soning. (PI. II, A.) The loss in soil fertility through the de- 
struction of humus must necessarily be a secondary matter. The 
food-producing capacity of the soil can be restored by the interplant- 
ing of such crops as would tend to do that work without future in- 
jury to Hevea. 
SPECIAL DISEASES 
ROOT DISEASES 
WATERY ROOT-ROT 
The watery root-rot fungus (Polyporus llr/nosus Klotzsch) has 
been widely known in the tropical world for many years. Specimens 
in the department herbarium show it to come from all the rubber- 
growing regions of the Eastern Hemisphere. * It was very early en- 
countered during the present investigation at Para and was found 
throughout the entire Amazon Valley, but chiefly in the lowlands. 
Specimens arc also present from southern Brazil. Its occurrence in 
the West Indies and Central America should be more thoroughly 
investigated. The fungus was first reported by Ridley, in 1904, as 
causing a disease on Hevea at Singapore. Since that time the fungus 
has been widely reported by various investigators. 
The discovery of the fungus in the Amazon Valley now makes it 
one of the commonest of the root diseases known to attack Hevea. 
The host range of the fungus is very great. Although only four 
rubber trees were found attacked in widely separated parts of the 
valley, the fungus Avas invariably present on either living or dead 
trees or stumps of jungle trees in the different regions visited. As 
has been shown by Petch, the host range of the fungus is also very 
great in the East. In addition to Hevea the fungus was recorded on 
the roots of living hosts of the jack (Artocarpus integrifolia) , coffee 
(Coffea ceraJbica), coco palm, Ficus sp., and cacao. 
The fungus was collected on a great variety of jungle stumps. The 
following is a record of these collections: 
On living stumps, on partly decayed roots, or roots of living trees of Hevea 
brusilii vn.sis ( Euphorbiaceae i . 
On dead log of mango ( Main/if era Indira; Terebinthaceae). 
On dead wood of Cecropia (Moracese). 
On dead stump of muiratinga (01 media maxima; Moracese). 
On dead stump of breadfruit (Artocarpus incisa; Moracese). 
On dead stump of assacu (Hura crepetans; Euphorbiaceae). 
On dead stump of Trichantheria gigantea (Ancanthacese). 
On dead roots of Inga sp. (Leguminosae). 
On dead roots of cutitiraba grande (Luciuna macrocarpa; Sapotaceae). 
On dead roots of munguba (Bombax munyuba; Bombacaceae). 
On dead roots of andiroba (Carapa guyemensis ; Meliaceae). 
On dead stump of orange (Rutaceae). 
On dead bark of Aydendron permaile (Lauraceae). 
On dead stump of Tecoma sp. (Bignoniaceae). 
On dead log of pao mulatto (CalycophyUuni spruceana; Rubiaceae). 
