1920 ENTOMOLOGICAL SOCIETY. ?3 



Cost of Treatments. Jn coniicction with the cost of treating cabbages per 

 acre of plants with corrosive sublimate in comparison with cost of applying discs, 

 it is of interest to record the following: 



Corrosive sublimate. — Total cost per acre, including labor and material: 



3 treatments $24 . 21 



4 '• 32.28 



Tarred discs. — Total cost per acre, including labor and material 16.75 



Effect of Cori;o.'S1ve Sublimate on Soil BACTEitiA. In order to deter- 

 mine the numbers of bacteria in the soil in the field where our cabbage maggot 

 control work was conducted, bacteriological soil tests were made by an assistant, 

 Mr. J. A, Flock, working under Mr. H. T. Gussow, of {a) soil treated with cor- 

 rosive sublimate and (h) untreated soil. These soil samples were taken on August 

 18th, when most of the crop had been harvested. Briefly, the data resulting from 

 these experiments clearly indicated that the corrosive sublimate treatment showed 

 no deleterious influence either upon the plants or on the relative number of soil 

 organisms present in the treated versus the untreated soil. Under field conditions 

 tlie applications of the corrosive sublimate mixtures certainly seemed to have a 

 stimulating effect upon the growth of the plants. 



In the control measures conducted in 1919, Mr. J. A. Flock and Mr. W. P. 

 Shorey, rendered valuable help. 



CABBAGE MAGGOT CONTROL. 

 L. Caesar and II. C. Huckett. 



In neither the Guelph nor Burlington districts did cabbages or cauliflowers 

 suffer any damage worth .speaking of in 1919 from the Cabbage Maggot {Chorto- 

 pliila hrassicae). Only 14 plants out of 7,000 in the plot were killed by the maggots 

 and these 14 were not in any one row but widely distributed over the field. 



Fortunately we included in our experiments a plot of radishes, and as radishes 

 were much worse attacked than cabbage some interesting and suggestive results 

 were obtained. 



We also devoted considerable time to trying to discover how corrosive subli- 

 mate controls the insect. 



The results of the work alono^ these two lines is given below : 



