160 RED ROT OF SUGARCANE. 



The infection of growing canes. 



It is generally stated by workers outside India that red rot 

 frequently arises from wound infection of the stem of the cane, 

 after it has developed far enough to be exposed to the attacks of 

 stem borer, that is usually in the second half of its growth period. 

 Some observers even hold that this is the only way in which the 

 disease can arise. The results of numerous inoculations, indeed, 

 fully prove that cane can be artificially infected through wounds 

 similar to those caused by insects. But, as was definitely stated by 

 Prinsen Geerligs' in 1898, wound infection will not sufficiently 

 explain every case of attack and we lioj)e to show that in Northern 

 India it is of secondary importance. 



Went, who first described the disease, obtained successful 

 inoculations by puncturing the rind with a fine needle and inserting 

 conidia of ColletotrlchuDi.'^ The infection was, however, localised 

 and after 20 days was chiefly confined to the inoculated internode, 

 traces only being found in the two higher up. Attempts to inoculate 

 the unwounded rind failed, except when very young internodes 

 were selected. Went concludes that natural infection occurs 

 chiefly through the holes made by boring insects, but that the place 

 of insertion of the leaf sheath at the node is also })ermeable. 

 Howard,^ ten years later, described the results of inoculations 

 with the same fungus in the West Indies. When wound inocula- 

 tions w^ere made on vigorously growing canes about 6 months old, 

 the fungus was found to have infected one or two internodes only, 

 after two months. In fully grown cane, during the ripening period, 

 however, infection was nuich more complete, up to 18 inches of the 

 pith being invaded in less than a month, in one series. Inoculations 

 at the leaf bases were successful in some cases but failed in others. 

 Lewton-Brain' did a limited number of inoculations in Hawaii in 



' Archief. VI, 1898, p. 450. 



* Wont, F. A. F. ('. Hot roocl-snot. Mcdcdcclinscn Proofstation • Wcst-.Iava," Aivliicl 

 V. (I. Java-Siiikcrindiistrie, I, 1803, p. 20."). 



3 Howard. A. On sonif di^oascs of tlic sujriiriMn.' in ilic \\<-s( Indies. Ann. nf IJot. 



XVII, i«o:$, p. '^T^. 



* Lcw-ton-Brain, J.. Pvf<l lU)t of the Sugainano stiui. Expur. Sl.t, n| lli.' Hawaiian Su^mi 

 Planters' Assoc, Div. of Patholosy and Physiology, Bid). S, lOOS. 



