152 RED ROT OF SUCARCANR, 



Sett selection. 



Ill 1906, alternate rows of diseased and healthy setts of a 

 Madras cane, known as Yerra, were planted at Pusa, on Febrnary 

 26th-27th. Prior to planting, the presence of Colletotrichum falcatum 

 had been determined in a large proportion of the canes from which 

 the diseased setts were cut. By the 6th week after planting a 

 decided difference was noticed in the two lots of seedlings. Those 

 from diseased canes were withering in considerable numbers. 

 Colletotriclium falcatum was found, in ])ractically every case 

 examined, in the young shoots, usually in the mycelial condition 

 but in several instances producing spores at the basal nodes. In 

 this, as in other cases where it was necessary to determine the 

 identity of the organisms present in diseased cane, considerable 

 use was made of the method of incubating aseptically removed 

 slabs, described on page 8 of the Memoir above referred to. White 

 ants, which are a frequent cause of injury to cane seedlings and 

 which complicate the diagnosis in many cases of fungal attack, 

 were absent from this particular crop, probably because the field in 

 which it was grown was liable to flooding. Sphceronema adiposum, 

 a fungus which is able to attack cut setts but not uninjured cane, 

 and a parasite belonging to the genus Cephalosporium, which will 

 be described in a subsequent paper, were found in a few cases. 



The field in which this crop was grown had not been under cane 

 in recent years and no other cane had been grown the previous year 

 within about half a mile. There was, therefore, no reasonable risk 

 of external infection and certainly no possibility of such an infection 

 as would lead to the death of many plants in the trenches planted 

 with setts from diseased cane,while the alternate, strictly comparable, 

 trenches with healthy seed escaped. The photograj)h leproduced 

 as Plate XII in the Agiicultural Journal of India for 1007, shows 

 the appearance of this plot on May 17th, and could hardly bo more 

 decisive. Under the micjoscope it was easy to trace the fungus 

 from the setts up into the young shoots, and throughout April and 

 May continued infection of the young shoots from their point of 



