BUTLER AND HAFIZ. 157 



As was pointed out formerly/ this fungus is not, in Northern 

 India, provided witli as suitable a mechanism for spore distribution 

 as in the case with most parasitic fungi. As long as the cane is 

 growing, there is comparatively little risk of air-borne contamination 

 from the stems of diseased plants in the crop. Dead and rotting 

 canes arc, however, frequently well provided with spores. Enor- 

 mous numbers are often found in the pith cavities of old canes. 

 These may contaminate the soil or get into the irrigation water. 

 They may thus reach the newly planted setts. Several experiments 

 have been carried out to ascertain whether infection of sound setts 

 may take place in this manner. 



In 1908, a short trench of Purple Mauritius cane was planted 

 on March 7th, the setts in one-half being previously dipped into a 

 suspension of Colletotrichmn spores, from a pure culture, in distilled 

 water. On April 30th there were 13 living shoots belonging to 12 

 setts in the non-inoculated half and 6 belonging to 6 setts in the 

 inoculated. 



Similar experiments on a larger scale, in 1909, gave conflicting 

 results, both inoculated and control canes showing a number of 

 withered shoots after two months. On May 14th there w^ere 167 

 healthy shoots and 27 withered in the control trench and 174 healthy 

 and 40 withered in the inoculated. White ants were bad in both, 

 but there was also evidence that Colletotrichum had reached the con- 

 trol trench, probably on the feet of the farm labourers, who walked 

 up and down from trench to trench during the irrigation of the crop. 



In 1910, the experiment of the previous year was repeated, the 

 cane being sown on March 12tli. Germination was slightly better 

 in the control than in the inoculated trench and on May 3rd there 

 were 325 shoots in the former and 304 in the latter. The control 

 trench, which immediately adjoined the inoculated one, developed 

 red rot as in the previous year, probably from infection during 

 irrigation. A similar trench some 30 yards away, but suppHed by a 

 separate distributary, was, therefore, also selected for comparison. 

 On June 21st there were only 255 healthy shoots left in the 



I Rntlrr. E. J.. Inr. cH.. lltOC. |,. IC. 



