408 PROCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 



afiected plants in the treated .plot being cut out at intervals. The 

 results of examination are given in Tables VI to X. The work of the 

 different agents of damage is shown in Table VIII. In Table XI are 

 shown the final results of the two plots and also the results of examin- 

 ation of the thick varieties of sugarcane grown by the Farm in Jhilli. 



As has been indicated in the plan, portions of both the plots adjoining 

 the wasteland became bare. This was practically due to termites which 

 ate the setts as well as the new shoots. The figures in Table VIII relate 

 only to the shoots which grew and were then attacked and not to the 

 setts which were eaten underground by the termites. The crop was 

 obtained only from the shaded portion of each plot as indicated in the 

 plan, which in the case of the treated plot was about 13,544 sq. feet 

 and in that of the untreated plot about 18,281 sq. feet. In calculating 

 the harvested result given in Table XI the entire plots including the 

 bare parts have been taken into consideration. (See Plate 69.)j| 



If we exclude the bare portion of each plot and calculate on the 

 approximate number of setts which covered only the shaded parts 

 which yielded the harvest, the number of canes which came to harvest- 

 able stage represents 111 per cent, of setts in the treated and 116 per 

 cent, of setts in the untreated plot. The weight of canes harvested 

 was 6,550 lb. in the treated and 11,440 lb. in the untreated plot. 

 Taking only the shaded portions of both the plots into consideration 

 the yield worked out at 21,066 lb. per acre in the treated and 27,259 lb. 

 per acre in the untreated plot. 



Therefore, we see that the cutting out treatment, instead of helping 

 the crop, actually does some harm to it. The same effect was observed 

 in the 1917 experiment with Purple Mauritius. The yield of the treated 

 plot of Purple Mauritius given in colunm 6 of Table V may be com- 

 pared with the yield of the same cane in 1918 given in Table XI. The 

 reason of the inefiicacy of the treatment is obvious. " Dead heart " 

 in young canes is caused by various agents which- are not removed 

 simply by the removal of the shoots with " dead heart.'' Scirpophaga 

 is the only insect which is likely to be removed if the shoot is cut before 

 the moth emerges. Diatrcea and other internal borers usually five so 

 far down the base of the new shoots that the majority of them are left 

 behind unless the shoot is cut near its point of growth from the sett. 

 In order to counteract the evil effects of borer attack the quicker and 

 more the tillering the better. The cutting-out treatment interferes 

 with tillering, as invariably some of the new side shoots, which begin 

 to grow from the affected ones, are either injured or removed in the 

 operation. Therefore the treatment causes a set-back to the crop 



