60 
early stages, losses could be made good by supplying, or out of the 
excess number of trees planted. Bancroft states that this treatment 
gave very satisfactory results, on areas badly attacked by Fames. 
Unfortunately, Poria and Ustulina may go on for very many 
years, sometimes tvfelve, -without being discovered, and the only 
safe rule is to treat all timber as a possible source of infection. 
The possibility of healthy looking trees being in reality diseased 
is especially serious for existing plantations in view of the very 
extensive thinning-out now in favour. When it is % intended 
to reduce the number of trees to the acre to less than 80 on 
plantations which were not clean cleared early, it will be found 
advantageous to examine the collar and roots of each tree — the 
expense should not be great. It is often pointed out that the various 
root parasites cannot be widely distributed in the jungle as this would 
soon die; it must be remembered, however, that although all these 
fungi are of comparatively slow growth as parasites on healthy wood', 
they are capable of very rapid growth on decaying wood, and will 
spread rapidly once the trees are felled, both under the ground 
(Fames, Poria ) and above it (Ustulina'). 
The ideal time for clean clearing is before planting up — but the 
removal of large jungle stumps in an undecayed condition entails 
prohibitive expense. It is, therefore, recommended that the smaller 
stumps and roots be taken up, while the large stumps be trenched, 
say with a trench of six feet radius and of a depth sufficient to sever 
all laterals. Parts of that laterals outside the trenches should be 
taken up aud no Hevea should be planted inside the trenches. As 
long as the stumps remain the trenches must be kept open. When 
somewhat decayed, e.g at the time of thinning out, the stumps may 
be removed at much less cost. 
Care must be taken as long as the stumps remain to examine them 
for fungus fructifications which should be destroyed as soon as they 
appear. In a field tlms cleared no rubber wood must be allowed to 
remain. Although the certainty of immunity given by clean 
clearing cannot be attained later, clearing of timber and stumps will 
always be found beneficial, except in old plantations already badly 
diseased (say more than 30 per cent, of trees) there the expenditure 
could not be justified. 
Prevention of spread . — Trenching is recommended for attacks by 
all root diseases, except perhaps Ustulina, for which, according to 
Sharpies, spores from fructifications produced on the surface timber 
are the chief source of infection. Trenches must be deep enough to 
sever all lateral roots, and wide enough to include all affected roots ; 
to be on the safe side, another trench should be dug around the 
neighbouring trees. The diseased trees are best cut out and burnt, 
the area within the inner trench being dug over to get out all 
diseased wood. Lime is of beneficial effect if supplying is 
undertaken. 
