638 RUBBER 



land which had been cleared of virgin forest for a number 

 of years and was then planted with Para rubber, very few 

 trees were lost. It was equally apparent that fewer trees 

 were lost on the undulating country than on the low- 

 lying flat country which is prevalent on the Malayan 

 coast. The reason was pointed out by Ridley several 

 years ago, viz., that in his opinion T. gestroi would not 

 attack a sound and healthy tree, and he attributed the 

 cause to root disease, although advancing no definite 

 proof. Experience has shown this assumption to be well 

 founded, although it did not meet with general approval 

 at the time, and is often refuted now. Trees which are 

 attacked by T. gestroi often show no signs of fungus 

 attack, as the mycelia are quickly devoured by the insect, 

 and the wood affected by the fungus is the first point of 

 attack. As very few trees show signs of the presence of 

 the pest until thoroughly hollowed out, indications of a 

 fungus attack are thus usually destroyed. That the 

 original trouble is due in nearly every instance to fungus 

 or to bad drainage causing root-rot may be taken as an 

 established fact. 



That the flat lands suffered more than hilly country 

 was only to be expected. The jungle on the flats is 

 usually heavier and the burns less satisfactory, resulting 

 in a network of scorched timber lying over the surface 

 of the soil. The damp soil in such situations and the 

 draining difficulties offer additional facilities for the 

 spread of root diseases and the increase of T. gestroi. 

 In such situations there is often a surface layer of peat, 

 which forms a connected network of fibrous matter and 

 small decayed roots. Such a combination of favourable 

 factors for the increase of root disease and T. gestroi is 

 absent on the hilly lands. 



At the commencement of the industry it was the object 

 of those concerned to plant as great an acreage as 

 possible in the shortest space of time. No attention was 

 paid to the rotting timber, and such conditions were 

 admirably suited for the rapid multiplication of the insect. 

 It quickly took advantage of the facilities thus offered, 

 and increased at an immense rate for several years. At 

 the time it was pointed out that a gradual diminution in 

 its numbers was to be expected as soon as mo'St of the 



