REPORT OF THE SOCIETY 27 



DUSTING AND SPRAYING SUGGESTIONS FOR QUEBEC 



C. E. Fetch, Entomological Laboratory, Hemmingford, Que. 



Our knowledge of chemicals used as fungicides and insecticides is increasing 

 each year and evolution in this work is proceeding satisfactorily. Each year a 

 new formula of an old remedy is found or chemicals new to the work arediscovered. 

 For example, London purple gave place to Paris green, which latter has been 

 largely replaced by lead arsenate, and now evidence is at hand of it being largely 

 discarded for calcium arsenate. 



Lead arsenate is used in the powder and paste forms, and while there may 

 exist certain conditions in which the latter is preferable, I think the advantage of 

 the powder form should cause it to replace the paste in all but these exceptional 

 cases. When the powder form is used there is at least equal killing power, more 

 constant analysis, less freight to pay, no time lost by mixing, easier manipulation, 

 and it can be kept from one season to another without loss. 



There has been and there still is considerable difference of opinion as to 

 whether calcium arsenate is a safe insecticide to use with lime sulphur. I am not in 

 a position to say definitely, but I have used it for two seasons at a rate of ^ lb. to 

 40 gallons diluted lime sulphur without any apparent injury. I have used it 

 without injury at a strength of ten per cent in a dust mixture of equal parts of 

 sulphur and talc. When used with Bordeaux mixture on potatoes I have found 

 it to be vastly superior to Paris green or lead arsenate. Its most serious draw- 

 back is that it cannot be used alone. This coming season it is to be compared 

 with lead arsenate when both are added to lime-sulphur solution. It is proposed 

 to carry this experiment over a 5-year period. 



An eminent authority on spraying stated a year or so ago that lime sulphur 

 lessened the apple crop as much as 50% or more. Since that statement was made 

 a great many, who had used lime sulphur successfully for years, have become 

 converts to Bordeaux mixture. Under extreme conditions Bordeaux mixture is 

 superior, but for conditions such as exist in this province, I believe careful applica- 

 tions of lime sulphur will give equally good results. Regarding the large reduction 

 in the crop there has been no substantial evidence to support that statement so 

 far as the province of Quebec is concerned. 



Hydrated lime is being used extensively now in spraying and the time is not 

 far distant when it will almost entirely replace the stone or quick lime. It is 

 cheaper and saves considerable time in the manufacture of Bordeaux mixture, 

 but my experience has been that this mixture does not adhere so well as when 

 quick lime is used. There are two grades of hydrated lime, one rich in calcium 



