60 



early stages, losses could be made good by supplying, or out of the 

 excess numbei" of trees planted. Bancroft states that this treatment 

 gave very satisfactory results, on areas badly attacked by Fonies. 

 Unfortunately, Porta and Ustidina may go on for vei'y many 

 years, sometimes twelve, 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 numbei- of trees to the acre to less than 80 on 

 plantations which wei-e not clean cleared early, it will be found 

 advantageous to examine the collar and roots of each tree — the 

 expense should not be gi'eat. 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 remembei-ed, 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 

 (Fomes, Poria) and above it (Uslulina). 



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 and 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 thus 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) thei'e tlie expenditure 

 could not be justified. 



Prevention of spread. — Trenching is recommended for attacks by 

 all I'oot diseases, except perhaps TJshdina, 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 ta get out all 

 diseased wood. Lime is of beneficial effect if supplying is 

 undertaken. 



