192 NEW SUGARCANE DISEASES 



The symptoms outwardly resemble those of red rot, so tar 

 as the withering of the top is concerned. The top leaves wither 

 back from the tip along the edges, the midrib remaining green 

 later than the rest of the leaf. The larger leaves below the crown 

 appear to suffer first, those at the apex remaining unaffected for 

 some time. When the leaves have fully withered, the cane is 

 found to be much lighter than normal. On splitting, the upper 

 part is usually pithy and dry in the centre, or even with a central 

 cavity along each internode, around which the pith is dry, white 

 and flaky. Lower down the pith may be still juicy but has a 

 curious translucent watery appearance ; still lower the centre por- 

 tion may be brown, while red streaks or patches may often be 

 seen, especially at the nodes (PI. 1, Fig. 2). At the base, where 

 the feeding roots arise, the red colour predominates and is 

 especially visible at the nodes. In old cases the lower internodes 

 also dry up and may develop a central cavity, surrounded by red or 

 brown pith. The roots arising from the basal nodes are usually 

 blackened and rotten, and the appearance suggests that the 

 disease enters the base of the stem from the roots. 



In the Jorhat cases the buds at the lower nodes had sprouted 

 and subsequently withered. The reddening was specially well 

 developed at the nodes from which these shoots arose. It is not 

 yet certain how far this sprouting of lateral buds is a symptom of 

 the disease, as it appears possible that the Jorhat attack is com- 

 plicated by the occurrence of a non-parasitic, sereh-\ike degenera- 

 tion of the cane, which requires further investigation. 



MicHiSCOpic examination shows that the roots and base of the 

 stem are invaded by a fungus. The mycelium is confined to the 

 definitely reddened parts, being absent from the translucent uppei' 

 portion of the cane. In the Jorhat cases the fungus was found 

 collected chiefly at the nodes, the intervening internodes being 

 almost free from hyphic until a late stage. The discoloured roots 

 always contain a considerable quantity of mycelium. In the 

 early stages the hyphiu run between the cells in the inter- 

 cellular spaces. Here they are usually extremely line, though 

 thick ones sonietimes occur. Later (jn, branches from the inter- 



