CONTROL OF WHITE GRUBS. 



5 



All plots in this experiment received the same cultural treatment. 

 The only factor that could not be controlled was the condition of 

 the soil. In section four the check plot unfortunately fell upon a 

 piece of bad soil which reduced the yield at least ten tons below the 

 average normal crop per acre. If we disregard this plot, we then 

 find that on six of the ten treated plots the yield fell below the check 

 plots. In all cases where a double dose was applied the yield was 

 lower than on the check plot. The carbon bisulphide had a detri- 

 mental effect on the growth of the cane plants. 



Altogether the results do not warrant a further use of carbon 

 bisulphide as a means of control for the white grubs in growing 

 cane, for although it may kill the grubs in the stool when first ap- 

 plied the effect is not lasting, and as the egg-laying season of the 

 beetle extends over a rather long period the land soon becomes re- 

 infected and at least three applications a season would be necessary 

 to keep the land free from the grubs. The expense of the material 

 would in any case render such an operation prohibitive. The liquid 

 is dangerous and disagreeable to handle, and furthermore it is in- 

 jurious to the cane, stunting its growth and often killing the plant. 



Carbon bisulphide and gasoline. 



In an endeavor to find a mixture that would be cheaper and less 

 injurious to plant life than carbon bisulphide, experiments were tried 

 with gasoline and various mixtures of gasoline and carbon bisulphide. 

 The following table shows the results obtained : 



Experiment IV. — Use of Carbon Bisulphide and Gasoline Against White Grubs. 



All experiments conducted with these two liquids consistently 

 showed that they had almost equal killing powders and could be mixed 

 MS desired. However, when applied to young cane all the mixtures 



