A. Sharples 155 



There is, as yet, no report of this fungus being found on rubber in Java or 

 in Sumatra. 



Brooks obtained the fructifications and as a result of his observations 

 estabUshed U. zonata as the cause of a collar-rot on H. brasiliefisis. An 

 account of his observations in Malaya up to the end of 1914 is given (i) 

 when he left for England. At the beginning of 1915 specimens were 

 obtained which necessitated a more complete investigation. This work 

 was carried on through 1915-1916 and various side issues are still under 

 consideration. A general account (lO) on economic lines was published in 

 1916; the following article includes all observations made since 1914 up 

 to the present date. 



Fetch (5) records several hosts for the fungus: Tea, Cassia Nodosa, 

 Benya ammomilla, Casuarina montana, Molia Dubra, Lafoensia Vandel- 

 liana, Denis Robmta, Citrus Decumana, Albizzia Molluccana, and 

 Grevillea sp. 



FIELD OBSERVATIONS ON DRY-ROT AND COLLAR-ROT. 



In Malaya, the disease is found on old plantations in every part of the 

 peninsula ; the fungus is not localised in its distribution as is the case with 

 Forms lignosus (Klotzsch). It attacks old rubber trees in the region of 

 the collar ; only in advanced cases does the fungus spread up the stem, 

 and it seldom reaches more than three or four feet above soil level. In 

 one case, however, the fungus has been found travelling from the collar 

 up through the heartwood of the stem into the lower branches, some 

 twelve feet high ; externally the tissues appeared healthy except for about 

 two feet above soil level. The fungus travels down through the heartwood 

 of the lateral roots in the same way. The diseased wood in an advanced 

 case is found to be dry and tindery, like touchwood, and running through 

 the diseased tissues conspicuous black lines are to be seen. When the 

 bark is removed, these black lines can be observed in some cases on the 

 outer surface of the wood and, if the lines are followed carefully, it will 

 be seen that they form thin plates of black tissue inside the wood, the 

 edges showing as black lines on the exterior. A longitudinal section 

 taken through the collar of a diseased tree shows these black lines run- 

 ning irregularly in the rotting tissues, often forming circles surrounding 

 dark coloured patches of diseased wood (PL III, fig. 1). 



There is no external mycelium associated with roots suffering from 

 this disease, though fan-shaped, white patches of a felt-like mycelium 

 may sometimes be observed on the exterior of the wood when the bark 

 is removed. The absence of external strands of mycelium distinguishes 



11—2 



