431 



Perak. An infected stump sent in to this Department for cxaniin- 

 ation exhibited nnmistaka)l)le characteristics of the root disease. 

 Further examination of the si)ot from which the tree had been 

 removed, shewed more advanced stages of the infection on the few 

 remaining laterals. On a recent visit to an estate in IVrak, the 

 writer found a similarly infected tree, the roots showing the cha- 

 racteristic red mycelial strands and plates adpressed to tlie surfac^e. 

 In the writer's belief, these are among the first instances of tlie 

 disease being found and identified in Malaya. 



A very good description of this disease was published in the 

 Tropical Agriculturist, Vol. LII, jSTo. 1 by Mr. Fetch. He states 

 in part that the appearance of the diseased roots is very variable 

 and in consequence its diagnosis is in many cases difficult. On 

 young trees its identification is fairly easy. The tap root tbcn 

 usually bears external nm-elium in a more or less young stage and 

 in that condition it is unmistakable. The mycelium forms stout 

 red strands on the exterior of the root which sometimes unite into 

 a continuous red sheet. The strands are smooth and tough on the 

 outside and vary in colour from bright red to brownish red accord- 

 ing to age. Frequently, adhering to the root, are found very small 

 stones and fine gravel. l)ut not so encrusted as with Brown rot 

 disease. The appearance of the diseased wood is also typical in the 

 case of young trees. It is somewhat soft and friable and permeated 

 with red sheets. These sheets often run in C3dinders in the wood 

 along lines of the annual rings. On older trees the indications are 

 by no means so clear. The roots which have been longest diseased 

 are generally soft and wet and on these there may be a net work of 

 narrow white threads between the bark and the wood. The fruc- 

 tification may sometimes be found at the collar of the diseased tree, 

 or along the underside of exposed lateral roots. It forms a flat plate 

 closely ajiplied to the surface of the root or stem. At first it is 

 yellowish white :. it then changes to reddish brown and finally to a 

 dark slate colour. Its thickness is usually about one and a hall' 

 millimeters and it may spread over an area of several indies. 



There is no doubt that the disease spread originally from jungle 

 stumps. Its recent appearance , on rubber estates, about twelve 

 years old, where it was not previously known, is prohably to be at- 

 tributed to the way in which the thinning out was done. It liad 

 been fonnd to develop from the stumps of tlie felled fiecea, where 

 the trees were 'Cut down to ground le\el and the stumps left to decay, 

 and is one of the most regular frequenters of rotting Hevea logs. The 

 spread from tree to tree is usually by direct contact of the roots: 

 however it has been demonstrated tliat the mycelium of this fungus 

 can travel from tlie diseased roots for some little distance througli 

 the soil. With regard to the rate at which the disease progresses, 

 the following may be noted: — Hevea was planted on newly cleared 

 land in June 1913; the trees began to die in 10'14: that is quite as 

 rapid as any other root disease. 



The treatment of Poria Jnjpobrunma follows the usnal lines, 

 but it is especially necessary that all Hevea logs should be removed 

 as the fungus develops chiefly on them. 



