32 



THE REPORT OF THE No. 36 



and walked diagonally at^ross the crop continuing from one side to the other in 

 a V-shaped manner, the strips where the liquid would fall being about lo fett 



apart at the wide end. tu. e+nT^.I 



From the half-acre plot U5 bags of good onions were harvested. Tl e stand 

 was certainly an excellent one considering the season. In two other nearby plots 

 of the same size, which were not sprayed, the work of the onion maggot was 

 readily seen and it was estimated that 20 per cent, of the plants were infested. 



These experiments were conducted on the farm of Mr. I. A. Farquharson. 

 near Rivermead, Que., which is close to Ottawa. We are very grateful to Mr^ 

 Farquharson for allowing us the use of his plots and for his kmdly interest and 



assistance in our work. . ,, , • , i ^ 



The cost of controlling the onion maggot with tjie above mixture, under 

 conditions prevailing in 1917, was about $1.10 per acre. This estimate includes 

 the cost of the ingredients, as well as a charge for the labour required to apply 

 the five applications. In cases where areas containing several acres were to be 

 treated, the cost per acre could, we think, be somewhat reduced. ^ , . , 



From the work which has been done near Ottawa, the results of. which 

 correspond with similar work accomplished elsewhere, it seems to us that, the 

 commercial grower of onions, in districts where the onion maggot is a regularly 

 occurring pest, should test out the value of the mixture under his immediate 

 local conditions. The cost of the materials is slight and the mixture can be 

 applied quickly even where a number of acres are to be treated. One acre can 

 be treated in "less than ten minutes. . . i' 



Prof Caesar: Whai is the formula for the poison bait reterred to . . 



Me Gibson- Five grams sodium arsenite, one pint cheap' molasses, dissolved 

 in one gallon of boiling water. Wo did think of trying mixtures containing 

 slices of onion, which bv some were thought to make the bait more attractive 

 to the flies but we did not think this would make any appreciable aiiference. 



Prof Caesar: Is there anv injury to the plants by the sodium arsemte and 

 molasses, and also will you tell me just exactly what you mean when you say 

 that it is spread diagonally on the field? 



Mr Gibson : There was no injury to the plants from the use of this mixture. 

 So far as the method of spreading the bait is concerned, the operator walks 

 across the field at one end, and continues crossing the field back ^gam to about 

 fifteen feet from where he first started, so that it is spread over thel held m a 



V-shaped way. 



Prof Caesar: Backwards and forwards? 



Mr Gibson: Backward and forwards across the field. It is not necessary 

 to apply it all over the onion patch. It is usually applied in the form ol largo 



drops. 



.Prof. Caesar: And the flies feed on the drops? _ • • . . 



Mr. Gibson: Yes. We found them feeding readily on the mixture. 



Prof. Caesar : Was there any difference in the amount of infestation in the 

 adjacent rows of the adjoining plots?- ' ' . . .' /'', .i 



Mr. Gibson: We found the infestation in the adjoining plots to be rather 



evenly divided. 



Prof Caesar: My idea was that in those adjacent patches you would expect 

 less infestation than vou would get further away, for the reason that the insects 

 would be nearer the bait and would therefore be controlled by it, to a greater 

 extent. For this reason of course you can always get better results ])y treating 

 larjie areas. 



