94 SCIENTIFIC REPORTS OF THE AGRICULTURAL RESEARCH 



idea could be formed of the part they were playing, but they 

 appear to be of very minor importance as pests. 



Records of observations on the pests of sugarcane at 

 Pusa were given in last year's Report. These observations 

 were continued during this year although it has not been 

 possible to keep such close observation on the different 

 varieties of cane as was done last year. The period of 

 injurious activity of the borers in cane extended from 

 March to August, when the total damage due to insects and 

 fungi amounted to about 35-5 per cent., due to the following 

 causes : — 



Fungal diseases ...... 21*8 per cent. 



Papua depressella ..... 8'3 ,, 



Dialrvca auricilia with a few D. venosata . 2'T ,, 



Scirpophaga xanthogastrella ... 1'9 ,, 



Termites ....... 0'8 ,, 



At this time there was a distinct difference between the 

 canes which would go to make up the harvest and those which 

 were retarded in growth by pests and diseases. The mon- 

 soon rains had stimulated the growth of the former and 

 they were growing vigorously, while the latter remained 

 stunted and ultimately died, and, although new shoots and 

 lateral branches were appearing, these would not add mate- 

 rially to the harvested result. The activity of the borers 

 after August was mostly confined to these stunted canes 

 and new shoots. 



As mentioned in last year's Report, the plot of Purple 

 Mauritius sugarcane had all " dead-hearts " and dry plants 

 systematically removed together with the insects found m 

 them. As this is the treatment usually recommended 

 against borers in cane, the results obtained in this plot and 

 in the other plots of thick canes which were left untreated 

 and undisturbed seem interesting and appear to show the 

 uselessness of the cutting-out treatment. The percentage of 

 non-stunted, harvestable canes actually harvested to the 

 number oP setts planted may be taken as a standard of com- 

 parison,* as this shows the number of canes which survived 



* The actual outturn of sugar would be the most satisfactory comparison between 

 the various plots, but this cannot be adopted at Pusa because sugar is not made here. 



