58 



Poria hypolateritia. 



This fungus, causing a wet-rot of Hevea was the subject of an 

 article in the August Agricultural Bulletin for 1916. It appears 

 since, that the specific name hypolateritia there given was not connect, 

 and the fungus is nearer to one recently described by Fetch in Ceylon 

 as Porta hypobrunnea. The matter has been referred to Kew, and 

 the final name will be settled by the authorities there. Whatever 

 the systematic name, there is no doubt of the presence of the fungus, 

 and of its characteristics, the chi^f of which is the wet I'otting of 

 attacked roots. This may vary from a slight dampness of recently 

 attacked roots only discoverable on splitting, to the complete 

 disintegration of the root to a jelly-like mass. 



A very delicate snow-white mycelium is sometimes produced on 

 the exterior, but no strands travelling through the soil have ever 

 been found. The exterior of the root is sometimes covered by a 

 very dark reddish skin of mycelium and bark tissues mixed ; this 

 skin is tough, and when freshly taken up can readily be detached 

 from the wood — serving to distinguish an attack of this fungus from 

 that of brown root disease ; in the latter case the external crust is 

 brittle and cannot be separated from the wood. 



Brown lines or plates of hardened fungus tissue are often found. 

 They differ from those produced by Ustulina in colour and texture, 

 being much finer and less branched. Broad brown bands also 

 occur, formed by the deposition of a substance akin to wound-gum. 

 Attacks of Poria sometimes cause honeycombing of Hevea wood, but 

 the phenomenon is more common when hard jungle woods are 

 attacked. Like Fomeg the fungus has been found both on hard and 

 soft woods, including many of the largest stumps such as are very 

 often left in otherwise cleared plantations. 



Perfectly developed fructifications are very rare ; more commonly 

 on the under-side of exposed i-oots, small patches of an imperfect 

 fructification develop. The fungus belongs to the same group as 

 Fomes — and the fructifications have the same form as the resupinate 

 form of Fomes, i.e., a plate perforated with many fine holes. The 

 colour is white when young, later becoming red-brown to black. 

 These fructifications are sterile, i.e., bear no spores, and cannot 

 spread the disease. 



It was first thought that the disease might be confined to special 

 •ireas, particularly flat wet lands— but it has since been found to be 

 distributed thi-ough the Peninsula. 



The mode of infection is by contact of lateral roots with jungle 

 stumps, or with other laterals ; and the peculiar danger of the disease 

 lies in its very slow rate of growth in living tissue, which makes it 

 possible for neighbouring trees to be infected — through laterals— 

 before the first infected tree is seen to be diseased. This insidious 

 method of attack is further aided by the partiality of the fungus to 



